This podcast contains a handful of visuals that we thought would be helpful, so we’ve published a video version of this podcast at https://youtu.be/NZ2qp06oET8.
The Testo 605i that Mark mentioned can be found at https://amzn.to/41TYFjs
To find the chart that Mark referenced, go to https://efficientcomfort.net/charts/.
We’re also including four screenshots that Mark shared during the podcast, which you can find below:
Check this link to IEB Unite: https://events.iebcoaching.com/IEBUnite2025
You can find Mark at https://besttampainspector.com.
Reuben Saltzman, Tessa Murry, and Mark Cramer delve into the intricacies of air conditioning testing, focusing on how home inspectors can improve their methods. They discuss the importance of understanding temperature splits, the role of humidity, and the need for advanced measurement techniques. Mark emphasizes the limitations of basic thermometers and advocates for more accurate tools to assess air conditioning performance. The discussion also covers real-world examples, practical applications, and the significance of airflow in HVAC systems. In this conversation, the speakers delve into the intricacies of HVAC measurement techniques, focusing on the use of advanced tools like the Measure Quick app. They discuss the importance of accurate temperature readings, the role of humidity in system performance, and the shift toward non-invasive testing methods. The conversation highlights the challenges faced by HVAC professionals in adapting to new technologies and the implications of energy efficiency on system performance.
Takeaways
Air conditioning is crucial for comfort, especially in humid climates.
Home inspectors often rely on basic thermometers, which may not provide accurate readings.
Temperature splits in air conditioning can vary significantly based on humidity levels.
Understanding latent heat is essential for accurate air conditioning assessments.
Advanced measurement tools can provide more precise data than traditional methods.
Humidity plays a critical role in determining the effectiveness of air conditioning systems.
Real-world examples illustrate the importance of proper testing techniques.
Airflow issues are a common problem in HVAC systems that can affect performance.
Using technology like hygrometers can enhance the accuracy of air conditioning evaluations.
The ideal temperature split for air conditioning systems typically falls between 18-20 degrees. Using two probes allows for the simultaneous measurement of return and supply air.
The Measure Quick app simplifies the process of HVAC measurements.
Accurate temperature readings are crucial for assessing system performance.
Non-invasive methods are becoming the preferred approach in HVAC inspections.
Humidity levels significantly impact the efficiency of air conditioning systems.
High-efficiency systems may struggle with humidity control despite their performance.
Understanding airflow and duct conditions is essential for accurate HVAC assessments.
Investing in advanced measurement tools can enhance inspection accuracy.
The HVAC industry is gradually shifting away from traditional gauge methods.
Education and resources are vital for HVAC professionals to stay updated.
Chapters
00:00 Introduction to Air Conditioning Testing
02:59 Understanding Temperature Splits in Air Conditioning
05:54 The Role of Humidity in Air Conditioning Performance
09:14 Advanced Measurement Techniques for Air Conditioning
11:46 Real-World Examples of Air Conditioning Testing
14:59 Tools and Technology for Accurate Measurements
18:01 Understanding Temperature Differential and Humidity
21:05 Practical Applications of Measurement Tools
23:55 Conclusion and Key Takeaways
31:31 Understanding Measurement Techniques in HVAC Systems
33:21 Advanced Measurement Tools and Applications
39:13 Streamlining Temperature Measurements
43:12 Cost and Accessibility of HVAC Measurement Tools
44:29 The Shift in HVAC Inspection Practices
45:34 Non-Invasive Testing Methods in HVAC
48:13 Key Factors Affecting HVAC Performance
51:12 Humidity’s Role in HVAC Efficiency
54:31 Challenges with High-Efficiency Systems
56:18 Resources for Further Learning in HVAC
TRANSCRIPTION
The following is an AI-generated transcription from an audio recording. Although the transcription is mostly accurate, it will contain some errors due to inaudible passages or transcription errors.
Reuben Saltzman: Welcome to my house. Welcome to the Structure Talk podcast, a production of Structure Tech Home Inspections. My name is Reuben Saltzman. I’m your host alongside building science geek, Tessa Murry. We help home inspectors up their game through education, and we help homeowners to be better stewards of their houses. We’ve been keeping it real on this podcast since 2019, and we are also the number one home inspection podcast in the world, according to my mom.
Reuben Saltzman (00:01.757)
Welcome back to the show. am here with two guests. Well, no, got a cohost and a guest both broadcasting from sunny Florida, making me super jealous today. Tessa, how you doing today?
Tessa Murry (00:13.764)
Hey, good to see you, Ruben. I’m doing well, thanks.
Reuben Saltzman (00:18.067)
Good, and I’ve got repeat guest, Mark Cramer, and Mark is here to educate us on air conditioners, on how home inspectors can better test air conditioners. How you doing today, Mark?
Mark (00:32.952)
Great, great, how are you guys?
Reuben Saltzman (00:36.263)
No complaints, no complaints. I mean, I could be where you are, but that’s all right. Before we dig into it, I want to give a shout out to our show sponsors, IEB, Inspector Empire Builder. What I’m promoting right now is the next big conference that IEB is hosting. This is IEB Unite. We got a bunch of in-person things we do every year with IEB, but this is the big one. This is where if you’re just going to go to one every year, this is the one.
Tessa Murry (00:36.632)
rate.
Mark (00:40.98)
Thank
Reuben Saltzman (01:04.723)
You do not need to be a member of IEB to attend this. I will have a link in the show notes, but it’s coming up May 28th through May 30th. This is in San Antonio, Texas. And besides all the learning, we do a bunch of fun stuff together too. Lots of team building, lots of camaraderie. If you’re a home inspector, you will be hard pressed to find a better group of people, more energized, more enthusiastic.
about this profession. It is a ton of fun, lots of energy. Check it out.
Tessa Murry (01:37.176)
Be ready for tough morning workouts.
Reuben Saltzman (01:39.859)
Be ready for some tough morning workouts. Yes. Yeah, we do like to do those. And that might be one of my highlights of the trips. May or may not be. But okay. So I’ve gotten Mark Cramer on. Mark, we just had you on a couple of months ago and we were doing our series with home inspectors all over the country talking about regional inspection differences. And one of the things we talked about on the show was
air conditioners and how to better test them. And I can’t remember who I was talking to, but we were talking about, you know, is there really a better way to test it? Because what we always do is we just, test the temperature of the air coming in. We check the temperature of the air going out. I know it’s a very limited test, but I don’t know if there’s anything better. And, you know, the consensus was kind of, yeah, that’s really all you can do as a home inspector. We can’t test refrigerant levels or any of that.
And I just kind of went, all right, so we’ll just keep doing what we’re doing. then Mark ended up listening to that show. And I think he must have called me in the middle of the show and he’s like, Ruben, I’ve got a better way to do it. I might be exaggerated a little bit, but he told me about it and it was, it was just way over my head. And I said, let’s, let’s, let’s get you on the podcast. let’s talk about it. So Mark correct.
Tessa Murry (02:59.436)
Hmm.
Reuben Saltzman (03:03.423)
everything I just got wrong and teach us please.
Tessa Murry (03:05.752)
you
Mark (03:07.469)
Well, that’s pretty much right. That’s pretty much right. just it now, you know, I’m a bit of an air conditioning nerd because in Florida, air conditioning is the most important thing in terms of living your life comfortably. I mean, far more important than than it is up where you live, Ruben. And as a result,
Tessa Murry (03:08.676)
This is.
Reuben Saltzman (03:09.919)
Okay.
Reuben Saltzman (03:19.881)
Sure.
Mark (03:31.949)
We pay a lot of attention to air conditioning here and we tend to learn a lot more about it than I would know about high efficiency furnaces, for example. If you ask me about those, I’m kind of clueless. Whereas you would know all about them in your climate. But it just kind of drives me crazy that home inspectors are testing an air conditioner with a $7 thermometer from Walmart.
Reuben Saltzman (03:41.758)
Yeah.
Tessa Murry (03:41.987)
Mm-hmm.
Tessa Murry (03:46.22)
Mm-hmm.
Reuben Saltzman (03:47.955)
Sure.
Mark (03:59.691)
when they’ve got a $3,000 infrared camera and they’ve got a $4,000 sewer scope and they’re using all this technology for other things, but they’re not using it for air conditioning when we have this much, better technology available today. So there better tools available today. They’re much more accurate and easier to use and there are better methods of evaluating the air conditioning system.
And there’s some additional parameters that we can measure beyond just that temperature split and that we absolutely should measure just beyond that temperature split. And there’s some basic things we can do, which is what most health inspectors would want to do. And then there’s some little more advanced measurements that people can take that the nerdy people can get into beyond the basic stuff. Then the other thing that drives me crazy is,
Tessa Murry (04:35.545)
Mm.
Mark (04:58.253)
And somebody said this on a podcast with you, which is what prompted me to call you when you said, should the temperature split be on an air conditioner? And they said 16 to 22 degrees.
Reuben Saltzman (05:15.602)
Okay.
Mark (05:17.229)
Well, which is it? Is it 16 or is it 22?
Tessa Murry (05:21.092)
I’m
Reuben Saltzman (05:23.528)
Okay.
Tessa Murry (05:25.102)
Does it matter? Apparently it does. We don’t know these things up in Minnesota.
Mark (05:25.271)
How do you know? Of course it matters. Absolutely. So, the answer to that question is what should the temperature split be? The answer is your favorite answer, Tessa, which is exactly. Now I’m pretty much known for that.
Tessa Murry (05:43.572)
It depends. Okay.
Reuben Saltzman (05:47.218)
I knew that was coming.
Mark (05:54.389)
saying that a lot also when I used to teach by the end of the week, I would ask students what’s the answer to this question. They would always say it depends because they’d heard that come out of my mouth 300 times by that point. So yeah, that’s the right answer. It really depends. And it depends a lot on the humidity in the house, which represents latent heat. So when we’re measuring or when we’re
Air conditioning, our air conditioning system is lowering the sensible temperature, but it’s also removing latent heat. And that latent heat is the moisture that’s in the air, or it’s contained within that moisture that’s in the air. And that has a huge effect on what that temperature split is gonna be.
Reuben Saltzman (06:42.153)
Mm-hmm.
Tessa Murry (06:48.836)
Okay.
Mark (06:51.313)
One good example that I used to use is if you take a pot of water and put it on a stove and you put a thermometer in it and you boil it, so that water temperature is going to be what? At sea level. Right. And if you put a thermometer in the steam coming off of that, that’s going to be what?
Reuben Saltzman (07:07.679)
212 degrees.
Tessa Murry (07:08.856)
Good 12.
Mark (07:17.921)
Take a guess. Yeah, it’s gonna be 212 degrees. But if you take your fancy infrared thermometer and measure the burner underneath that pot, it might be six or 700 degrees. So we’re pumping that six or 700 degrees of heat into that water and it never gets above 212 degrees. The steam coming off of that water never gets above 212 degrees. So.
Reuben Saltzman (07:17.961)
The same? I don’t know.
Tessa Murry (07:17.976)
I have no idea. Okay.
Reuben Saltzman (07:21.8)
Okay.
Tessa Murry (07:33.476)
Mm-hmm.
Mark (07:46.731)
That heat is a constant. We can’t create it. We can’t destroy it. We can only move it around. Where’s it going? It’s going into the steam, the humidity that we’re creating in the air as latent heat. Tessie, you’ve been new to Florida. When you walk outside in the summertime, especially, it feels miserably hot because it is miserably hot.
Tessa Murry (08:02.478)
Changing forms takes a lot of energy from a liquid to a gas.
Mark (08:14.859)
And a lot of that heat is humidity. So that’s why we have that, if you see on the TV news, that feels like temperature. It feels like temperature is always higher than the actual air temperature here because that feels like temperature is accounting for that latent heat, that humidity that’s in the air. Okay, so our air conditioner does the same thing. We boil a refrigerant.
Tessa Murry (08:19.128)
Yeah.
Mark (08:44.051)
in the evaporator coil. And when we boil it in there, our heat source is the air, that’s like the burner, and our gas that’s created in that coil is like our humidity, there’s latent heat in that gas. So we’re taking out both sensible heat and latent heat when we’re passing air over that coil. We can measure the sensible heat with a thermometer, but we can’t measure the sensible heat.
or the latent heat with our thermometer. So we’ve got to measure that some other way. And we do that by either taking a wet ball temperature. And if you recall the days of a sling psychrometer, that was a device that had a dry thermometer and another thermometer that you put a little.
Reuben Saltzman (09:15.689)
Late.
Tessa Murry (09:15.796)
latent defeat.
Mark (09:40.343)
piece of wet cloth over and you swing that around and you get a wet bulb temperature and a dry bulb temperature. So that wet bulb temperature is actually accounting for the humidity that’s in the air. So I’m going to, and to show you how much effect that actually has.
Tessa Murry (09:47.072)
Mm-hmm.
Mark (10:04.405)
I’m going to give you some numbers here.
and I lost them. Give me a second. I gotta find them again here.
Tessa Murry (10:14.052)
was going to say, how many people have seen a sling psychrometer? Probably not too many. Ruben, have you seen one in action?
Mark (10:14.516)
Thank you.
Reuben Saltzman (10:20.767)
I have seen them in books and I have never actually used one myself.
Tessa Murry (10:24.502)
Okay.
Well, I’ve never used one but back in school, the U of I had a professor, Bob Sebe, and he, I remember he had one and he showed us how it worked and what to do and that was when we were talking about psychrometrics. So take me back to my college days here, Mark.
Mark (10:47.885)
I don’t think I’ve ever seen one, but I’ve seen pictures of it. That’s about it. And the other thing you have to realize about that latent heat is that whenever you change the state of a substance, when you boil that liquid refrigerant and turn it into a gas or a vapor, there is a huge amount of heat involved in that process. For example, to…
Reuben Saltzman (10:53.631)
Okay.
Tessa Murry (10:54.37)
Yeah. Yeah. Yeah.
Mark (11:17.517)
raise the temperature of a pound of water from 32 degrees to 212 degrees as a liquid takes about 180 BTUs. To go from 212 liquid to 212 vapor takes 970 BTUs, about six times as much. So there’s a huge transfer of heat when we make that change of state. That’s why we pressurize our air conditioning system, why we boil.
Tessa Murry (11:43.332)
Mm-hmm.
Mark (11:46.689)
this refrigerant is because we can grab a huge chunk of heat by that process and transfer it outdoors very easily. I we could have an AC system that just had water circulating through it and we could, you know, as long as the water temperature is lower than the outdoor air temperature, we could transfer heat that way, but it’s not very effective. We’re not gonna move a lot of heat until we get to that change of state.
So I have, here we go. So this is a real world example. This is an inspection I did in January here in Florida. Outdoor temperature was about 65 degrees. measuring the relative humidity in the house, we had a temperature split of 13 degrees, 67 return air.
54 supply air, 13 degree split, had 70 % relative humidity. So you can’t check a system when the humidity’s that high in the house. You can’t walk into a house that’s been sitting there, turn on the air conditioner and check it, because you gotta get rid of that latent heat first. So two hours later, boy, you’d gotten the humidity down to 57%, which is still a bit on the high side.
Our return air was 67. Our supply air was 49 degrees, which is an 18 degree temperature split.
Tessa Murry (13:18.212)
So I have degrees cooler.
Reuben Saltzman (13:20.314)
Yeah.
Mark (13:22.477)
Now, and the difference is, and it’s 70 % relative humidity, we can’t measure that latent heat using a thermometer. The other interesting thing there is that 70 % of our return air was 67. Two hours later, at 57 % humidity, our return air temperature was exactly the same, 67 degrees. So.
that temperature did not drop at all during that period because that system is busy taking out the latent heat. And until we get that latent heat load down to a reasonable level, we’re not gonna start to reduce the sensible temperature that we can measure with a thermometer.
Tessa Murry (13:51.577)
Hmm.
Reuben Saltzman (14:07.711)
So, I mean, basically, this air conditioner has been running for two hours. And if you’re only looking at the thermostat, you’re going to say, look, it was 67 degrees two hours ago, it’s still 67 degrees. My air conditioner is broken. It’s not doing a darn thing. But in reality, it has been removing a ton of latent heat from the air, which our thermostat doesn’t measure. I’m tracking. Got it. Thank you.
Mark (14:25.301)
Right. Right.
Tessa Murry (14:31.908)
Yeah.
Mark (14:36.127)
Exactly. You got it.
Tessa Murry (14:36.228)
Yeah. Yeah. Can I ask a quick question, Mark? What would be a good range for relative humidity in a house to get an accurate assessment of the AC? Do you want it to be somewhere between 30 and 50 % relative humidity or 40 to 60 % relative humidity? You said 70 was way too high. What are you looking for?
Reuben Saltzman (14:37.201)
Okay.
Mark (14:59.367)
Okay, so the answer to the question is, it doesn’t really matter. So I’m going to share with you a chart here. Let see if I can figure this out.
Reuben Saltzman (15:06.363)
It depends.
Tessa Murry (15:08.452)
You’re okay.
Reuben Saltzman (15:19.967)
So he’s sharing a chart with us and for anybody who’s just listening, I will take a screenshot of this and I will put it in the show notes and I will also likely try to upload a video recording of this podcast. We normally don’t do that because you know, if you look at us, you’d be like, hey, they got faces for radio, but we’re gonna…
Tessa Murry (15:44.878)
you.
Reuben Saltzman (15:45.695)
We’re gonna we’re gonna try we’re gonna try it. All right, you’ve got a beautiful little chart here Please talk us through us through it mark
Mark (15:53.579)
Okay, now this is our temperature drop, temperature differential, the difference between the return air and the supply air at the air handler. And all of these measurements that we’re talking about assume that we have the correct volume of air flowing over this coil. Because if we don’t, these numbers are gonna change because the air is the heat source. So if we turn down the air, it’s like turning down the burner, things are gonna get colder.
So if you have a dirty coil that’s clogged up or a filter that’s very clogged up, these numbers are not gonna be what you’re gonna see. You’re gonna see a lower temperature, bigger temperature split. I’ve pulled a dirty filter out of an evaporator unit and had the temperature split go up by six degrees because
Reuben Saltzman (16:25.567)
Okay.
Tessa Murry (16:52.558)
Mm-hmm.
Mark (16:53.385)
that dirty filter was blocking the airflow, which is the heat. When we pull it out, the heat goes up. Our temperatures go up.
that make sense? No, I can see a dazed and confused look on your face, Reuben.
Tessa Murry (17:09.858)
Well, so Mark, we’re looking at a chart that shows along the x-axis, the horizontal axis on the bottom, temperature, and it looks like it’s return temperature. What is the y-axis?
Mark (17:20.127)
Okay, so our normal indoor temperature we aim for when we’re air conditioned is about 75 degrees, somewhere right in here. This is our return temp, which is the temperature inside the house. These lines represent various humidity levels. So if we walk in this house and it’s 75 degrees and the humidity is 70%, you know, we’re gonna get about a 14 degree temperature split.
If we go back a couple hours later and it’s 50%, we’re gonna get maybe an 18, 19 degree temperature split. If we’re in Las Vegas and the humidity is 30 % inside the house, then we’re gonna get a temperature split of maybe about 25 degrees at that same 75 degree return air temperature.
Tessa Murry (17:49.484)
okay, okay, I got it. So the y-axis, yeah.
Okay.
Tessa Murry (18:01.846)
Right.
Mark (18:15.754)
So as the humidity goes…
Tessa Murry (18:15.86)
So this is helpful. Okay, so the y-axis is your temperature split. so you can see these. Yep, okay. That makes sense.
Mark (18:21.704)
This is your temperature differential.
Reuben Saltzman (18:25.567)
And to make it really simple, lower the relative humidity, the higher the temperature split.
Mark (18:34.933)
Yes, because why is it?
Tessa Murry (18:35.031)
Yes.
Reuben Saltzman (18:38.695)
late in heat.
Mark (18:40.165)
Right, there’s less latent heat. Now in our part of the world, when contractors size an air conditioner, we’re sizing not only for sensible heat removal, but also for latent heat removal. And about a third of the capacity of our system goes to latent heat removal. Now in your area, it would be less, it would probably be more like 20, 25 % when they do that.
Tessa Murry (18:40.44)
Mm-hmm.
Tessa Murry (19:01.304)
Hmm.
Mark (19:06.805)
and complex calculation to figure out what size system you need in that house. In Las Vegas, it would be even less because they have much, much less latent heat there. So we could use, yeah, no.
Tessa Murry (19:09.081)
Mm-hmm.
Tessa Murry (19:22.852)
I’m just going to add really quick, sorry to interrupt, I was just going to add, this makes so much sense. Thank you for pointing this out and bringing this to our attention because you’re right, it takes a lot of energy to remove moisture from the air. So if you’ve got a lot of humidity in your air, you’re not going to have as much of a temperature differential because that energy is going to removing the moisture instead of cooling the actual air temp.
Reuben Saltzman (19:47.838)
Yeah.
Mark (19:47.947)
Right, now you say removing moisture, but what we’re really removing is heat. We are removing moisture also. We’re dehumidifying at the same time. We’re removing moisture and it’s draining on the ground outside, but it’s really heat that we’re concerned about when we’re talking about majoring a temperature split at an air hammer inside the house. So this is an approximation. Now there are other things we could look at.
Tessa Murry (19:52.694)
Right. Yeah. Yeah.
Yeah.
Tessa Murry (20:00.302)
Right, right.
Tessa Murry (20:05.934)
Yeah.
Tessa Murry (20:10.969)
Yeah.
Mark (20:20.457)
Let me see if I can…
Reuben Saltzman (20:20.831)
And real quick, while you’re looking for that mark, the dazed and confused look is I wasn’t, I’m not sure I was totally tracking what you’re talking about with removing the furnace filter. Cause in my mind, you’ve got a really dirty furnace filter. If you’ve got very low airflow over the evaporator coil, the air coming out is going to be very cold cause it’s moving very slowly.
and then you pull the dirty furnace filter, you’ve got more air coming out and the air coming out should actually be warmer and you will decrease your temperature split. Is that right?
Mark (21:04.365)
I lost there.
Reuben Saltzman (21:06.939)
Okay, well, see, I can’t understand when you say you can’t understand what I say, but Tessa’s nodding. I think we’re both saying the same thing.
Tessa Murry (21:10.692)
Okay, maybe, okay, let me make sure I understand. Okay, let me try to rephrase this and this is how I understand what you said, Ruben. If you’ve got a really dirty filter, it slows down the airflow over the A-coil and so the air will get much colder because it’s moving slower. You take out the dirty filter, the air moves faster, it can’t cool off as much and so it’s warmer air coming out and so your temp, okay, yeah.
Mark (21:26.995)
Exactly.
Mark (21:33.523)
Exactly. So your temperature split would go down. And just think of it like turning up the burner and turning down the burner on itself. When you turn down the burner, you restrict the airflow, you turn down the burner, then it’s going to get colder.
Reuben Saltzman (21:37.011)
Okay.
Reuben Saltzman (21:40.349)
Yes, yes. Yep, okay.
Tessa Murry (21:42.806)
Okay. Okay.
Reuben Saltzman (21:51.303)
Yep. All right. Cool. All right. We’re all on the same page. Thank you. Perfect.
Mark (21:52.407)
so your temperature split would increase.
Tessa Murry (21:52.438)
Okay. Same page.
Mark (21:56.653)
Okay, so we did that looking at humidity, but a little bit better way of doing that is looking at the return air temperature, which is on the left over here, and the return air wet bulb temperature, which is just simply a measurement of the amount of moisture in the air. So this is where that sling cyclometer thing comes in again.
wet bulb, dry bulb. So if we had a 75 degree return air temperature and we had a wet bulb temperature of 62 degrees, we should have a temperature split right around 19 degrees.
Tessa Murry (22:44.644)
This is like a psychrometric chart for an AC temperature differential where it should be based on the humidity level and the temperature.
Reuben Saltzman (22:44.872)
Okay.
Mark (22:45.8)
if our wet bulb is
Mark (22:54.349)
Exactly. This is just a little bit more precise, accurate representation. So if our wet bulb temperature goes up and we’re up to 72, which is really super humid, and we’re back to 75, our temperature split will be 10 degrees. So depending on our humidity here, which is represented by this return air wet bulb, at 75 degrees, our temperature split could go from 23 to 10 degrees.
Tessa Murry (22:59.268)
Mm-hmm.
Mark (23:26.325)
across this chart.
Tessa Murry (23:26.521)
Mm-hmm.
Mark (23:29.995)
So the answer is it depends. It depends on what this number is, which represents the humidity inside the house.
Tessa Murry (23:34.081)
Mm-hmm.
Reuben Saltzman (23:39.135)
Okay.
Tessa Murry (23:40.292)
Yeah.
Mark (23:41.079)
So do you have a slime psychrometer? No, don’t get one.
Tessa Murry (23:43.972)
No. But we do have tools that can tell us what the relative humidity is in someone’s house and the temperature. And that’s what you need to know. Right?
Reuben Saltzman (23:45.769)
Yeah.
Mark (23:55.917)
Absolutely. So we have much, much better tools. I love, and they’re different brands, but instead of that $7 thermometer from, well, I used to buy mine at Target instead of Walmart, but instead of that $7 thermometer, I use like a $100 thermometer. And I use multiple thermometers. The brand I like is Testo.
And they have a thermometer, hygrometer device that you can stick it into that supply duct and you can stick it into the return. And it will tell you what the dry bulb temperatures are and what the wet bulb temperatures are also. So, and I’ll, let me change this share thing here.
Tessa Murry (24:26.24)
Mm-hmm.
Tessa Murry (24:43.214)
Cool. Very cool.
Tessa Murry (24:54.67)
So do you carry around a chart with you, Mark, then too, once you get the dry bulb and the wet bulb times? Do you carry around a chart so you can look at that chart and say, OK, this seems like an acceptable temperature split?
Mark (25:04.683)
Yes, but I pretty much know, you know, but so you can calculate that very precisely.
Tessa Murry (25:08.161)
Yeah, of course, yes.
Mark (25:16.154)
My sheer thing is not working here for some reason.
Tessa Murry (25:22.052)
So on the low range, help me understand, low range for an acceptable temperature split. Let’s just say it’s a very high wet bulb temperature. There’s a lot of humidity in the air. The AC is just turned on. You might get temperature split of 10 degrees, and that might actually be acceptable. But then after you run it for a while and it reduces the dry bulb temperature, then you might have a temperature split of wet bulb. Yeah.
Reuben Saltzman (25:46.483)
wet bulb temperature. It reduces the wet bulb temperature.
Mark (25:51.724)
Yes.
Tessa Murry (25:52.012)
Okay, then you might have a temperature split of like 15, and that’s okay too. So what would be this range that you commonly see that temperature split falling in for ACs that are working properly?
Mark (26:07.757)
18 to 20 degrees is about normal.
Tessa Murry (26:15.128)
time.
Mark (26:17.229)
if you’ve got the humidity under control and your airflow is correct. Again, this is assuming correct airflow, which is something that’s very difficult to measure. I mean, it can be done, but it’s not easy to do, not something I do on a regular basis.
Tessa Murry (26:18.414)
That’s a very narrow, yeah.
Tessa Murry (26:25.037)
Okay.
Reuben Saltzman (26:25.823)
Mmm.
Reuben Saltzman (26:29.395)
Yeah.
Tessa Murry (26:36.716)
Well, we actually we were talking about this with some specialists at the Energy Conservatory up in Minneapolis. They create tools for measuring things like this. They have an app and they have a tool that actually will tell you what the pressures are in the airflow and how it should be adjusted. And I’ll tell you from talking to them, it sounds like most furnaces or air handlers don’t have the proper airflow.
Mark (27:05.261)
It’s one of the number one problems. And I’m familiar with that tool, that tool that they have that you can stick in a return, costs about $2,500. If I was still working full time, I’d probably buy one of those just for the heck of it so I could play around with it and major airflow because airflow’s probably the number one problem we have in systems. All right, so.
Tessa Murry (27:08.205)
Yeah.
Tessa Murry (27:13.859)
Yeah.
Thanks.
Tessa Murry (27:32.928)
Yeah.
Mark (27:35.381)
I take those testo probes and I connect them to a testo app and they just connect automatically and you can map these probes. In other words, you can put a label on your probe that says return air, one that says supply air so that you know which one is which. And I just took this measurement today on my system.
Our return air temperature was 69 degrees. Our supply air was 50 degrees. Relative humidity was 61.4. Now here’s our wet bulb temperature, which was 60.4. And if we go back and look at that chart, which I’m not gonna do because it’s difficult to switch here, but that is right, gonna be almost exactly what that chart says. With this return air temperature,
this wet bulb temperature, we’re gonna end up with that 19 or 18 and a half degree temperature split.
Tessa Murry (28:42.584)
That’s right where it should be.
Reuben Saltzman (28:43.679)
OK, so you’re taking you’re taking this testo device and the one you’re using, it looks like it’s the six zero five I. And you have two of those.
Mark (28:54.529)
Right.
Reuben Saltzman (29:00.689)
Okay, you use two of them, you connect them to the app on your phone, and you’re taking the two measurements at the same time, and then you’re comparing those to that slide chart that you shared with us earlier to make sure that the numbers jive.
Mark (29:02.433)
Yep, I used to say.
Tessa Murry (29:03.172)
Thanks.
Mark (29:19.425)
Right, but look, if my humidity is 50 to 60 % and I’m at 18 degree split, 19 degree split, 20 degree split, that’s good. I don’t even have to look at the chart. I’m gonna know that’s because the more you use these things, you become familiar with them. You know what’s normal, what’s not normal, or what’s abnormal. So that’s a basic measurement that you can take that is far, far more effective or…
Tessa Murry (29:30.788)
Hmm.
Reuben Saltzman (29:32.723)
Okay.
Mark (29:49.133)
effective than or accurate than just measuring the air temperatures alone. These thermometers are extremely accurate. I know they’re calibrated. When you put them side by side, they’re within a percentage of one degree. You’re getting very, very accurate temperatures. They’re designed for air conditioning to measure air temperatures.
Tessa Murry (29:55.438)
Mm-hmm.
Tessa Murry (30:14.66)
Mm-hmm. was going to say they also, I mean, besides the wet bulb temp and the actual air temperature relative humidity, they also show you the dew point on there and the absolute humidity. I think that’s a nice feature to have too. Just thinking in cold climates, in real time, you could show a client why they’re getting condensation on their window based on their current humidity levels and air temp.
Mark (30:38.251)
Yeah. Yeah.
Yeah, absolutely. Yeah, I’ve never thought of that because we don’t have the problem.
Tessa Murry (30:48.54)
Not a problem where you are. Yeah, yeah, this can just kind of be a visual as to why you have condensation. Yeah, yeah. So it’s a multipurpose tool. I could see it being helpful for more than just AC measurements, but just understanding indoor humidity and moisture, condensation, all that too.
Mark (30:52.567)
Right. We get condensation on the outside of the windows.
Mark (31:09.069)
So yeah, this is a basic, this I do every day and basic temperatures and your wet bulb temperature, your humidity, whichever way you use that. But this answers the question of which is right, 16 or 22 degrees.
Tessa Murry (31:31.588)
Mm-hmm. Mm-hmm.
Reuben Saltzman (31:31.657)
Sure. And just for the sake of argument, Mark, why couldn’t someone just own one of these devices, take one reading and then take another reading one minute later? Okay.
Mark (31:42.581)
You could. This is just easier. Now I’ll take a screenshot of this. Or actually what I do is I’m looking at this on my phone and I take a picture of it with my camera because if I take a screenshot, then I got to get that into my computer when I get back. But if I take a picture of it, it’s already with all the other pictures. So I’ve got a picture of this and I’ll just put this in the report. So I’ve got an accurate representation of what was going on when I was there. So if there’s a question later,
Reuben Saltzman (31:47.743)
huh.
Reuben Saltzman (32:04.403)
Okay.
Tessa Murry (32:10.188)
Okay.
Mark (32:12.909)
you know, this picture is in the report. So there’s no question in anybody’s mind as to whether or not this is operating properly when I was there.
Tessa Murry (32:24.374)
Okay. And just to clarify, Ruben, you were saying you could just, could you just buy one of them and take one reading now and one reading later? But I think, are you using two of these though, Mark, putting one in the return side and one in the supply side to get a measurement at the exact same time? okay, so it’s, you’re just taking that measurement at the same time you got two probes so you can do it together. Okay.
Reuben Saltzman (32:30.663)
Exactly.
Mark (32:45.117)
Right, So return air, supply air. And again, I’ve got these two pro maps to return air and supply air. So when the app opens and we turn those on, the one that’s in the return air shows up here is return air. Otherwise you confuse them when you’re doing it.
Tessa Murry (32:53.38)
Okay.
Tessa Murry (33:01.4)
Yeah, nice, okay.
Yeah, yeah, it’s a nice if you’re trying to if you’re if you’re putting this in your report, like you are and taking a picture of it, it’s nice to have the data points from the return and the supply side showing up at the same time side by side for comparison. So it makes sense to have two probes that way, I think.
Reuben Saltzman (33:06.793)
Next time.
Mark (33:21.527)
Yeah, yeah.
So now I’m using more than two probes now. So I’m gonna go into the more advanced level of measurement. And there is an app for this.
And it’s called Measure Quick. It’s for air conditioning contractors, but there’s a free version that you can use that will give you a whole bunch of additional measurements and tell you a whole lot more about how the system is actually working. So for this, we’re measuring, and you can do this without the app, but the app just makes it a whole lot easier to.
So all of these systems operate exactly, or they’re designed to operate exactly the same. So they’re designed to an AHRI standard. the temperature difference between the air and your coils and your refrigerant are exactly the same on all of these units.
within a certain efficiency range. So if we’re looking at our evaporator performance, our evaporator temperature is gonna be our return air temperature minus about 30 degrees for a 13 sear up unit, plus our required
Mark (35:18.143)
superheat, which represents that latent heat in the refrigerant. And if we take that return air dry bulb and subtract
that 30 degrees and add in our superheat, whatever that happens to be. And it’s usually about 10, 12 degrees for almost every unit. Then we’re gonna come up with a temperature that represents what our suction line should actually be.
Reuben Saltzman (35:44.775)
Hmm.
Tessa Murry (35:45.828)
Thanks
Mark (35:46.611)
So I’m going to measure my two indoor air temperatures. I’m going to measure the outdoor air temperature. And I’m going to measure the suction line temperature and the liquid line temperature. Now, I can calculate those on a piece of paper and see if I’m within the right range. Or I can use this Measure Quick app, which shows me my return air dry bulb temperature, my wet bulb temperature, my
supply dry bulb. And this represents what, if we put gauges on this system, this represents what the pressures would actually be. This is a representation based on temperature. And all we’re putting those gauges on there for is to measure the pressure, which we then convert to temperature.
So.
Mark (36:47.085)
This shows me my suction line temperature here at 56 degrees. My liquid line temperature is 84 and my superheating subcooling. And it graphically tells me that I’m in the right ranges here.
Reuben Saltzman (37:05.277)
And so to sum this up, you’re taking your dry bulb temperature, well, you’re taking your return temp and your supply temp, and you’re also grabbing the humidity levels in those measurements. And then you’re going outside, you’re measuring the air temperature, you’re measuring the temperature of the suction line and the supply line or the high pressure line.
Mark (37:05.397)
without really having to know anything or calculate anything.
Reuben Saltzman (37:32.591)
and you enter those five numbers into an app and then it kicks back whether all of these numbers are in the green or they’re not. Is that a concise way of saying it?
Mark (37:45.197)
It’s simpler than that. I don’t enter them into an app. The app grabs them from the probes. So those testo probes are connected to the app and it’s reading those temperatures directly from the probes. I don’t have to put anything in. All I in is, I put in the, and that’s really all I have to put in. can put in, I put in a number for superheat, usually 12 degrees for higher efficiency systems. And I put in a number for sub-cooling.
Reuben Saltzman (37:50.576)
OK.
Reuben Saltzman (37:59.379)
Okay.
Mark (38:15.433)
which is what’s going on at the condenser where we are removing that heat. And that number is usually found on the outdoor unit label. In this case, it’s nine degrees on my, this is, I just took these this morning on my air conditioner, my heat pump at home, and it’s a 15.2 sear heat pump. It’s new. But I don’t, I can’t,
give you a piece of paper where you can calculate these, but using this major quick app, don’t have to calculate.
Reuben Saltzman (38:52.905)
test.
Tessa Murry (38:52.932)
For somebody who’s never measured all these temperatures, mean, the outdoor temperatures, the refrigerant line, the suction line, all these things, describe how long that takes and how you do that quickly. there, yeah, brief explanation. I’m trying to picture what you’re actually doing.
Reuben Saltzman (39:07.049)
Thank you. Yes.
Mark (39:13.757)
Okay, so.
On a TXV system, which almost everything is today, everything that’s modern is a TXV, we’re going to measure the suction line temperature, that’s the cold line, the big fat one, at the air handler. So I’ve got a clamp type thermometer, testo clamp, I’m going to put on there. I’m going to put my two, what were they, 950is in the return of the supply. Outside, I’ve got another
Reuben Saltzman (39:46.175)
- 605 out.
Mark (39:47.981)
Test code that just measured air temperature. I’m gonna set that next to the condensing unit in the shade, not on the sun. And I’m gonna put another clamp thermometer on the liquid line at the condensing unit. Then I’m just gonna let them sit.
Tessa Murry (40:05.646)
Okay.
Reuben Saltzman (40:06.665)
What are these clamp thermometers look like? I don’t know about these.
Mark (40:12.119)
So looks like a, if you think of a squeeze type clamp.
Reuben Saltzman (40:21.396)
huh. Yeah.
Mark (40:21.505)
that you would use in woodworking, for example. It’s just like that, only it’s got a little thermistor on one side of it that squeezes it against the refrigerant piping and very accurately measures the temperature of the refrigerant line.
Tessa Murry (40:37.412)
I’m picturing like a chip clip. I have no idea if that’s… Okay.
Mark (40:40.585)
Exactly. It’s a similar concept. Yeah. Only it’s a little bigger than that, but it fits in one hand. Now there are some that screw on that it’s a clamp that kind of screws together, but the Tesla ones are just like a clamp you use with your hand. So they’re very easy to use.
Tessa Murry (40:46.776)
Okay.
Tessa Murry (40:51.35)
Hmm.
Reuben Saltzman (40:54.601)
Well, Tesla, I’m Googling this and I’m coming up with the testo temperature clamp probe kit for the testo digital manifolds. And there’s a pair of them here and they look exactly like chip clips. But the pads, instead of being flat, are slightly curved. Maybe that’s what Mark is talking about.
Tessa Murry (40:56.718)
Yeah. Uh-huh.
Tessa Murry (41:12.516)
funny nice Yeah, okay, okay Yeah Okay Yeah, yeah, so okay, so I’m guessing you know when you when this is something you’ve done every day you can install the temperature probes and the supply and return and the clamp on the the What is it the suction line on the inside by the air handler?
Mark (41:17.857)
Yeah, that’s an exact big chip clip there.
Mark (41:30.997)
and so on.
Tessa Murry (41:41.412)
and then the other clamp outside and then the other gauge for temperature on the outside. You can do that really pretty quickly then. It’s just letting it gather the data points and…
Mark (41:50.699)
Yeah, it’ll take about five minutes to do it the most.
Tessa Murry (41:55.446)
Yeah, wow, you’re just, yeah, it doesn’t take that much more effort than just doing the temperature rise. You just need the tools to do it.
Mark (42:03.303)
Right, right. And this MajorQlick app is actually pretty incredible. It’s really amazing the work that’s gone into that and the science behind it. And there’s a lot more stuff in there than we would ever need as a home inspector. There’s an advanced version of this that you have to pay for where you can take a…
Tessa Murry (42:24.011)
and
Mark (42:29.005)
picture of the barcode on the equipment and it’ll actually populate the whole application with all the parameters for that piece of equipment using AI. But that’s beyond what we need to do, but know, AC guys, they can make a nice visual report with all the information for their customers. All I want to know is, you know, am I on right here? Is it working? All right.
Tessa Murry (42:38.167)
wow. Okay, cool.
Tessa Murry (42:49.577)
Yeah. Yeah.
Reuben Saltzman (42:55.131)
Okay, I think I found the app. You said it’s called Measure Quick, HVAC, and the logo for the app, it’s a little with a big green Q. Is that the one? Okay.
Mark (42:59.799)
Right.
Mark (43:07.531)
All right, like this one right in here.
Tessa Murry (43:12.334)
So, okay, question. How much do these tools cost then, roughly, to be able to gather all this data and take these measurements?
Reuben Saltzman (43:13.066)
yeah, yeah, yeah, okay. All right, yep. All right, perfect. All right.
Mark (43:23.501)
I think those test stuff things are around a hundred bucks a piece.
Reuben Saltzman (43:30.591)
Yeah, I think I think the one you were showing that it’s gone up since you bottom last. I think they’re about 150. So you got a pair of those at 150. And then it looks like you can buy a pair of clamps. I don’t know if these are the right ones. They’re selling a pair for 78 bucks. Or maybe if you get the more expensive individual ones, it looks like they’re about 100 bucks. So all in maybe about $500 worth of tools.
Tessa Murry (43:39.044)
Okay.
Tessa Murry (43:47.172)
Thanks
Tessa Murry (43:55.427)
Okay.
Mark (43:55.819)
Yeah, yeah. And again, this is a more advanced form of measurement. It’s not every home inspector is going to want to do this. I mean, that’s for the nerdy people.
Tessa Murry (44:07.606)
Well, and that was my next question. I don’t think probably any home inspector that I’ve run across in Minnesota has does this. Ruben, have you met anybody that takes these types of measurements? Okay, I’m wondering who does that in Florida? Besides you, Mark, do you run into home inspectors that do this?
Reuben Saltzman (44:18.621)
Not once, never, nope.
Mark (44:20.576)
No, because…
Reuben Saltzman (44:24.787)
besides you.
Mark (44:26.207)
No, buddy. No, I won’t.
Tessa Murry (44:29.454)
Okay.
Reuben Saltzman (44:29.618)
Okay.
Mark (44:30.615)
because they don’t know about this app and to do it manually, you can do it manually on a sheet of paper, but you’ve got to take your indoor dry ball, you got to subtract 30 degrees, you got to add 12 degrees for super heat and that’ll give you a suction line temperature. Then you got to measure the suction line temperature and compare those. So this has already done that here.
Tessa Murry (44:49.749)
No. No.
Reuben Saltzman (44:55.271)
No thanks.
Tessa Murry (44:55.426)
No, thanks. Yeah. Okay.
Mark (44:59.671)
For the outdoor unit, you gotta take the outdoor air temperature, gotta add, depending on the efficiency, 15, 20 degrees, subtract your sub-cooling, nine, 10 degrees, whatever it is, and that’ll tell you what your liquid line temperature should be. Well, this has already done that right here. So, as long as we’re in that green, we know those temperatures are good.
Tessa Murry (45:14.691)
Hmm.
Tessa Murry (45:22.094)
Yeah.
Reuben Saltzman (45:23.647)
Okay. Okay.
Tessa Murry (45:25.41)
Well, thank you for coming on our show today and explaining how HVAC contractors actually check systems to see if they’re working right and figure out what the problem is.
Mark (45:34.251)
Well, actually this method is kind of new for air conditioning people also. So the trend today is to never put gauges on a system. Just to use this app like this and just take these measurements that I’ve taken and that gives you a very, very accurate representation of what your gauges would tell you anyway.
Tessa Murry (45:40.289)
Is it? Okay.
Reuben Saltzman (45:59.923)
Okay.
Mark (46:01.069)
And there’s some resistance to that. There’s some people that don’t really, know, older AC guys that don’t really get their heads wrapped around that yet. So it’s kind of new for AC guys also. But there’s a whole lot of reasons you don’t really want to put gauges on systems because you risk losing refrigerant. You risk contaminating refrigerant with
Tessa Murry (46:12.757)
newer technologies.
Tessa Murry (46:17.54)
Huh.
Mark (46:28.813)
different types of refrigerant that might be in your hoses and gauges from the last unit you were at. And it’s not really, the other thing is you don’t know what those pressures should be when you walk up there.
Tessa Murry (46:31.46)
Hmm.
Mark (46:44.471)
So, you know, once you’ve started up a system commission, there’s not really any reason to put cages on it anymore.
Tessa Murry (46:46.254)
So.
Reuben Saltzman (46:52.528)
Interesting.
Tessa Murry (46:52.887)
So this is a non-invasive way of checking the system because you’re just putting clamps on things and you’re, I mean, you are taking measurement of the air temp going in and out of the system. So you might have, you know, a little invasion there, but yeah.
Mark (46:54.231)
This is so insane.
Mark (46:59.309)
Exactly.
Mark (47:04.681)
And you see up at the top here it says AC, not invasive. That’s the type of test we’re doing. There’s a bunch of different tests you can do. You can use this with gauges too, the sal.
Reuben Saltzman (47:11.177)
Sure.
Tessa Murry (47:11.202)
Okay. Yeah.
Tessa Murry (47:15.958)
Okay. So I didn’t know that the common method of doing it for AC contractors was, I mean, it’s invasive, but they’re, they’re shifting over to doing this, it sounds like.
Reuben Saltzman (47:16.809)
Hi.
Mark (47:27.853)
Some of them are, yeah. But it’s like getting the homeless vectors to go from that $7 thermometer to the $100 thermometer.
Reuben Saltzman (47:43.709)
Yeah. So, well, it seems like the next step here, Tess, I think you need to meet up with Mark. You need to go over to his house and I need you to shoot a video of him doing this for us. OK.
Tessa Murry (47:44.74)
Hmm. Yeah.
Tessa Murry (47:57.284)
I would love to I’d love to see you do this in person. Yeah and learn from you Let’s plan on it
Mark (48:03.194)
Yep, we can do that, absolutely. Yep, absolutely.
Reuben Saltzman (48:07.399)
Okay, all right. Well, Mark, any closing thoughts? Anything else we didn’t cover? Because this is mind blowing and it takes me a little bit to digest this. I may be ordering a few of these tools and testing them out myself.
Mark (48:13.622)
Mark (48:23.241)
It took me a long time to digest this too. So don’t feel bad. And I’ve been doing it manually with a piece of paper, which is even more mind blowing and complicated or difficult to comprehend. So again, all this assumes that your airflow is correct. And the first thing that you should be looking at as an inspector is
Tessa Murry (48:23.968)
and nice.
Reuben Saltzman (48:26.143)
Okay.
Tessa Murry (48:38.474)
longhand.
Reuben Saltzman (48:39.806)
Yeah.
Mark (48:52.373)
Is that evaporator coil dirty? Is that filter extremely dirty? That’s going to affect your temperatures because that affects airflow, is heat. So that’s really the most important thing you’ve got to look at to start with is condition of that coil indoors and the outdoor coil also.
Tessa Murry (48:55.246)
Yeah.
Reuben Saltzman (49:13.183)
And maybe just, yeah.
Tessa Murry (49:14.062)
This is just one piece of the puzzle. Sorry to interrupt you, but I’m just thinking this is one piece of the puzzle of diagnosing if your system is cooling properly. I mean, there’s a lot of other reasons why it may be malfunctioning or not cooling right. It could be restrictions in airflow or too much supply, enough return, dirty evaporator coils, filters, fan speed is wrong, all those things. But this is just a snapshot of some of the data points that will tell you, the temperature split is within this acceptable range and it looks good or it doesn’t.
Mark (49:14.893)
Thank
Mark (49:43.019)
Yeah, and one other point you would want to look at is if you have a return duct in an attic or wherever long return duct system outside the living space, you might want to take a temperature reading inside the house and compare that to the temperature in your return air duct at the air handler or furnace wherever you’re at. And if there’s a big difference there.
then you got to return air leak. And you’re going to get an abnormal temperature split because you’ve got a huge amount of latent heat. If you’re sucking, you know, humid air out of the attic and that’s at 105 degrees and you know, 70 % humidity, that is going to affect the operation of the system also. So that’s another thing that you you got to look at is that duct system.
Tessa Murry (50:21.55)
Mm-hmm.
Mm-hmm.
Okay.
Tessa Murry (50:34.628)
Mm.
Reuben Saltzman (50:38.525)
Yeah. Okay. All right. Well, this is a lot to comprehend, Mark. Thank you.
Tessa Murry (50:39.257)
Yeah.
Mark (50:47.405)
Sure, sure.
Tessa Murry (50:49.22)
Thanks for blowing our minds, Mark, and making us realize that what we’re doing is very inadequate for assessing whether or not an AC is working right.
Reuben Saltzman (50:49.567)
.
Reuben Saltzman (50:54.911)
Ha!
Mark (50:58.494)
Well, you’re not alone there because there are very, very few home inspectors that understand any of this stuff. It only took me 30 years to figure it all out too.
Tessa Murry (51:12.536)
Well, my takeaway from this big picture is like the humidity really matters for how an AC unit should perform or how much it’s cooling with the temperature split is. just be aware of that. it’s really humid or really dry, that temperature differential will change.
Reuben Saltzman (51:28.029)
Yeah, yeah, super humid, low temperature differential.
Mark (51:28.075)
Yes.
Right. And if you’re walking into a vacant house where the system hasn’t been on and you’re in air conditioning weather, it’s going to run for a long time to get down to a normal temperature split.
Tessa Murry (51:33.24)
Yeah.
Reuben Saltzman (51:43.913)
Sure. Okay.
Tessa Murry (51:45.006)
Yep. Doesn’t mean it’s not working right though.
Mark (51:47.701)
And if you’re going back and looking at, you know, if you’re looking at this right here, return air, roll of humidity, you know, until you get that down, you know, into a more normal range, then, you know, your temperature split doesn’t really mean a whole lot. It’s not gonna be, you know, accurate representation of how that system is operating.
Reuben Saltzman (52:13.127)
Excellent.
Tessa Murry (52:14.456)
Let’s not get into a discussion then of what a quote normal range for indoor relative humidity is.
Mark (52:21.339)
well.
Mark (52:25.95)
You tell me what is it.
Tessa Murry (52:27.908)
It depends, It does. It does. Yeah.
Mark (52:29.949)
It depends. It depends on where you’re at, doesn’t it? Because in Florida, you know, it’s a whole lot different than other parts of the country. And in Minnesota, it’s a whole lot different in the winter than it is in the summer. So it really depends. The other thing, you know, this humidity is kind of high here. And as these systems get more efficient,
Tessa Murry (52:41.476)
for sure.
Tessa Murry (52:45.908)
Yes, yes. Yep.
Mark (52:58.177)
they are actually worse at removing moisture from the air. That’s one of the ways they squeeze more efficiency out of these systems. there are gonna be, I think coming down the road, there are gonna be some issues with that. And if you think about mini splits, the number one problem I have with mini splits is humidity control.
Tessa Murry (53:26.862)
Really?
Reuben Saltzman (53:26.975)
Hmm.
Mark (53:27.735)
because they are super efficient and they’re typically oversized. And the contractor thinks, well, this is a variable speed unit. It can run at all these different speeds. even if we don’t have this big cooling load, we can run this system that’s going to remove humidity. But these super high efficient systems do not remove a lot of humidity as much as the older system did.
Tessa Murry (53:33.571)
Yeah.
Reuben Saltzman (53:52.165)
Interesting.
Tessa Murry (53:53.486)
That is new that I’m just digesting this. Another piece of information that’s new to me is that it’s not just a system being oversized that can be problematic for being able to remove humidity from the air. I can struggle with that if it’s oversized, but you’re saying newer high efficiency cooling systems are less able to remove humidity as well? Yeah. Okay.
Mark (54:14.509)
efficient and even as I. Yeah. Yeah.
Tessa Murry (54:18.724)
That is a big problem. I think we’re moving towards needing just whole house dehumidification systems, especially in humid climates, as we build more energy efficient airtight structures with efficient cooling systems.
Mark (54:31.604)
Absolutely. You’ll find out, Tessa, that we have more mold problems down here in the wintertime than we do in the summertime. Because summertime, we’re dehumidifying 24-7. The wintertime, we’re not running that air conditioner very much. We’re not dehumidifying very much, but the humidity is still high. I mean, this is March. The humidity inside my house is 61%. And that’s after running the system for a little bit.
Tessa Murry (54:44.301)
Yeah.
Tessa Murry (54:50.2)
Yeah.
Yeah.
Yeah.
Tessa Murry (54:59.79)
Tell you what, my skin appreciates it, Mark, but my house doesn’t. Yeah.
Mark (55:01.037)
Yeah. Yeah. Yeah. So I have had multiple cases of people who have many splits who have just some developed some horrendous mold problems because again, oversizing and it, you know, from a logical standpoint, you would think that, okay, this highly variable speed system
Reuben Saltzman (55:04.724)
Yeah.
Reuben Saltzman (55:15.475)
Mmm.
Tessa Murry (55:15.842)
Wow. Wow.
Mark (55:29.677)
is going to be capable of running at a lower load condition and removing humidity, but they don’t.
Tessa Murry (55:35.78)
So interesting. Ruben and I were just talking about recently on another podcast about how energy efficiency doesn’t always guarantee better performance. You can actually create more building durability issues, moisture issues with that improvement. So it’s not only true for like a building envelope or house, it’s like the actual mechanical systems as well.
Mark (56:02.603)
Yeah, there are always unintended consequences.
Tessa Murry (56:06.058)
Yes, unintended consequences.
Reuben Saltzman (56:09.37)
Yeah. Well, Mark, if people want to reach out to you, how can they get ahold of you? You got an email or a phone number you want to throw out or website.
Mark (56:17.517)
My website is besttampainspector.com. Or they can just search for my name, they’ll find me.
Reuben Saltzman (56:22.993)
Okay.
Cool. Well, and for the listeners, if you got any thoughts, question, well, if you got questions, don’t send them to me. Ask Mark, cause I’m not going to be able to answer, but you got any thoughts, you’re welcome to email me or Jessa. Our email is podcast at structuretech.com and Mark can’t thank you enough for sharing your wisdom. Really appreciate it. This is great. Mind blowing. This is why I do the podcast.
Tessa Murry (56:47.043)
Yeah, thanks, Meg.
Mark (56:48.492)
Let’s do it.
Tessa Murry (56:52.708)
Where can people find that chart, Mark, that shows them what’s an acceptable temperature split or temperature differential? Okay. Thank you.
Reuben Saltzman (56:57.169)
I’ll put it on the show notes, yes.
Mark (57:00.333)
You can find them online.
Let me look at my history and see where I got that because I don’t remember.
Mark (57:25.431)
By the way, if you Google mini split humidity problems, you will come across just all about load buff.
Tessa Murry (57:36.29)
Now you’ve talked me out of getting a mini split, Mark.
Mark (57:36.493)
people are having all these problems and very few of the answers that you’ll read are very good, but just tells you exactly how big of a problem it is. If you search for HVAC calculators, you’ll find another really good
Reuben Saltzman (57:39.262)
Right.
Tessa Murry (57:43.768)
Mm-mm.
Mark (58:06.605)
document that help you understand this is published by Testa. It’s called the AC Application Guide and it’s about 70 pages that explains all of these fundamentals and the more technical aspects of how these systems work and how you can take measurements.
Reuben Saltzman (58:33.393)
further boggle my mind.
Mark (58:35.309)
It’s air conditioning applications guide and you can find that at testo.com.
Tessa Murry (58:35.768)
Mm hmm.
Tessa Murry (58:46.254)
Okay, thanks Mark.
Reuben Saltzman (58:48.093)
Yeah, thank you. Appreciate it. All right, Tessa, I will catch you next week. And I’m looking forward to that video you guys make. All right, take care.
Mark (58:50.167)
Thank you.
Tessa Murry (58:56.376)
Sounds good. See you next week. Thanks for listening. Yeah. Bye.