Heat Pumps anybody here? Uh Miss Brian's class last week. Okay, we will review a couple things Brian put together this slide for me. So uh, my job was pretty easy I can stand up here and go over my experience with heat pumps, testing in heat mode and hopefully um, if you pay attention I will get less tech support calls in uh, heating than I did last year, right? All right, let's see what he has on the menu. Oh I Literally used this already this week.

so I'm really I don't I'm I don't know why you put that up there. It's kind of embarrassing. Um, however, the facts speak for themselves which is probably what this is all about. I am the best.

Um, this will be the best class you've ever been to. Instructor Mentor Life Idol Enough about me and that's joke we've used already. This is my family. um, that's a horse that's not mine I spent three months on that in Canada but in Canada I learned the importance of heat pumps.

Um, although they don't really use heat pumps for their Winters out there, um, this is just some old material Brian had on here which I'm not really sure. Okay, so back to heat pumps. Part two: Auxiliary heat. Uh, this is what he went over last time.

um I just wanted to hit a quick refresher before we cruise on because this is all about heat pumps. Uh, and a couple of you weren't here, but um, testing our auxiliary heat to burn off anything that smells bad. um Adriel rightly pointed out multiple times last week that the best way to do that is at the thermostat and then then if you are outside of some sort of limit, the thermostat has a limit for it or it's not engaging. Find out why or jumper it out.

Um, you guys are doing commercial. You're not really going to be testing your uh heat strips on a commercial application and smoking somebody out inside of you know the space. If you're doing a maintenance and the space is being used, maybe not a great idea. Uh, the the tech I used to ride with on the Rtus.

When he would do the heat strips, he would pull them out or at least visually look at them. If they had a lot of junk on them, he'd pull them out and clean them off instead of just uh, burning them off inside the unit. So if they do are coated in a lot of junk, you can get them clean without smoking out the inside of the building, right? Okay, uh. Heat strip, wire and breaker sizing.

Um, this is crucial to not making an absolute disaster and also, uh, just diagnostic problems like Breakers tripping when when they don't need to things like that. So um, I have this up here just so that you guys know that the few of you that weren't here last week that, um, actually sizing your wire and your Breakers exactly as a data tag list for that heat strip is crucial for safety. Um, but you don't always have to memorize this. You can use a data tag and when you're thinking about wire size right here, which is really important, then you can um either Google it or look it up or ask for this information.

Just being aware that you can find it if you don't have it memorized yet. just being aware that you can find this information quite easily is crucial. Uh, feel free to go back and look at the class uh for more information on that from last week. It was great as Brian always is.

We briefly t uh um, talked about the 90 340 relay and the interlock ability so that you always bringing the blower off on whenever the heat strips come on. Um, another good reason for testing at the thermostat is to see how it responds. Uh, if it actually is bringing on the blower and if you have this working properly right now, if you have your uh, residential X13 blowers, then it just plugs into a different speed. So when white is energized, the blower runs at a different speed.

So there's a lot of ways you could. You could tie in low voltage to this interlock whenever the heat strips call the bower calls, or you could tie in high voltage through your blower. Not high voltage through your heat strips, but high voltage through your blower. Cool.

All right. So we're going to focus on heat pumps, checking them in cold weather. Um, Brian Mentioned this last week. some of the concerns that customers have.

Let's dive into here. Um, you get these calls where people are freaked out and worried about the ice and so here this is. Picture is a good demonstration of normal looking ice versus not normal looking ice. And so I don't want to have any calls this winter from somebody who sees Frost in their coil And that's their version of a problem, right? We're we're going to get a lot of frost on our coil running in heat mode when it gets cold.

When we get down below 40, we're getting in the frost area right? And that's normal. That's what it needs to do in order to pull in heat from the outside air. So understanding that, don't panic when you see something different. I've never seen ice on a condenser coil before.

That's fine. Let's just keep moving through and find out. Now if you are caked in ice as the picture shows on the bottom, that's a problem, right? Okay, so abnormal signs would be uh, thick sheets of ice or completely no heat inside the house. This is another thing.

You can talk to the customer when you're going through your diagnostic problems. Um, when it goes into Defrost, what happens to, uh, the evaporator coil in our air temperature inside? uh, it would normally go back to cooling mode and defrost. Yep, so it goes back to cooling mode and Defrost. So your blower inside is now running through a coil that is in cool mode and the purpose of that is so that outside your condenser that was the cold evaporator now has the hot discharge gas going through melting the ice.

But that means that inside the house we're getting cold air. so it does activate your backup heat in order to like offset how cold that is. But you'll get that complaint in the middle of the night. All of a sudden I felt this cold air and so um, Defrost usually goes for about 10 minutes and then we come out of it.

So an issue with Defrost could be we don't actually have heat, a backup heat working and so it's freezing air that comes out or it could be just less warm and the customer needs to be educated on the fact that this is normal and in Florida we do a lot of Education because Defrost doesn't happen every year. Uh, also weird noises. Steam people talk about their unit smoking. They see the unit trying to run, but the fan not spinning outside.

All that's normal right? So you have a lot of ice that needs to melt really quick. There's going to be, um, a lot of steam coming off of that look like smoke on here. We have changes in air flow. Okay, they're just talking about the customer noticing the fan not spinning.

the changes in air flow. If you do have your fan continuously running and defrost it uh, usually means that somebody just hooked the fan to the top of the contactor and bypassed the relay on the board. Um, and it will still defrost but it's much harder. Now you're you're working.

The cold air is still being pulled against the coil while the hot discharge gas is spinning through. so it will defrost. but just a much slower process. less efficient.

The customer is going to be stuck a little bit longer with the cold air blowing inside the house. Okay, checking charge and cool mode. Uh, what are some of the important changes in how you hook up in cool mode with your gauges? When you're testing pressures, you got to hook suction H the common suction common suction. That's right.

why not just stay with uh, the suction we normally hook up to in cool mode cuz in mode is to discharge. So let's talk about uh, what happens? what changes in our heat pump when we're actually switching from cool to heat? So in cool mode, we have our condenser coil outside where the hot discharge gas gets cooled down and it displaces heat into the outside air and it turns into a liquid pumps inside to our evaporator where our evaporator is really cold, it's absorbing heat and then that pumps outside on our suction as a a superheated vapor. and then we repeat that cycle. The reversing valve actually shifts the direction of refrigerant going to your evaporator coil and your condenser.

So now the compressor always sucks in the cold. Vapor Gas always discharge the hot vapor gas so nothing in the compressor gets switched. The direction of flow into the compressor, the direction of flow out. You always have a discharged line coming off the top of that compressor.

You always have a suction line going into that uh compressor, but the rest of the system gets switched. The reversing valve redirects the flow of refrigerant and we actually are now, uh, pumping our hot discharged gas straight out of the compressor into the suction line the one we can normally grab and it's cold pumping it straight to the evaporator coil. And once that evaporator coil is blazing hot, the cold air of the house is coming across it. It's getting rid of its heat into the cold air of the house.

So now we've effectively turned our evaporator coil into a condenser coil. Yep. But we still need to grab heat from somewhere in order to produce heat. So we are grabbing heat from our outside air.

And in order to do that, that means that the coil outside needs to become an evaporator and be lower in temperature than our outside air. So if we're trying to grab heat from 35 air, our evaporator coil and the refrigerator in it is going to have to be colder than 35 and significantly colder in order to be efficient than 35 to grab whatever heat it can. And you take that heat. Let's say it's 35 outside and you've absorbed it into cold refrigerant.

and your refrigerant is probably more like, uh, after it's absorbed the heat, it's probably more like 20, maybe 25. Um, going into that compressor. You can't really heat a house with 25 anything, right? So that's the magic of the compressor. You have all the heat energy there now.

it just needs to smash it and compress it and activate all those molecules. Get them angry, get them moving, the friction, and we have high temperature that we can work with same energy. Same heat that was outside in your outside air gets pumped inside, but at a high pressure high temperature. So the the important thing to note on this: Your outside is now your evaporator coil.

Your inside is your condenser. Quil So when you hook up your suction big large suction line, it's going to always be your discharge and then your liquid line. What's that going to be now? Liid line your liquid line. Exactly.

The difference is the direction of flow. not that it's not liquid. So um, more accurate on a heat pump is to call the suction line the always vapor line because if it's discharge or suction, it's still going to be Vapor So you could call the vapor line liquid line, right? Okay, common, Uh suction? Port What does that tap into? Where do? Where does that little tiny common suction port on a split heat pump go back and tap into common section the reversing valve before it, before it, before the reversing valve. Yep.

so the section before the reversing valve which is your common suction as we talked about already, The compressor. always. Uh, there's nothing changes with it compressor. So it Taps into the suction.

Somewhere between the compressor and the reversing valve where things don't change, right? And um, then let's talk about the difference in hooking up between. like, say, a carrier system train Linux or literally any other system. There's a few Goodman that are the same as the carrier, but right here in this picture. we have our Um carrier setup and where's our metering device? Yep, right there on the piston.

and if you look at the direction of flow, we're flowing into the condenser, we're hitting our piston before we actually hit the port. The service port. Which means that if we try to get a accurate reading of our liquid, we're not going to be able to hook up there. The Piston is going to restrict the flow.

so we're going to have a a pressure and temperature drop before. Um, before we actually have that service port. So the other direction on a setup like this, where you have the Piston there, that liquid line reading becomes obsolete. Um, don't try to use it and get confused in your diagnostic, right? So you don't actually have a liquid.

Typically, you don't have anywhere to to read liquid in that situation. Which a lot of you commercial guys doing Rtus and package units, that's pretty common to not have a liquid access anyway. Um, and so then you'll know. Notice on this, the manufacturer is going to have a chart that looks like this and it'll give you high pressure low pressure readings.

And so that high pressure is your discharge gas. Now on the suction. That's where your high pressure goes. The low pressure is the common suction port, and then, uh, on every uh other setup.

what do they use as a metering device? Txvs Txvs Yeah, So Txvs are going to typically be inside the condenser and if you're wondering if it's a piston or a TXV, look in the condenser. Follow the liquid line. If the liquid line doesn't come into a TXV we have a piston in this flared connection piece. here.

it's not actually a flare. I Forget what it's called now. CH That's great. I'll take that.

Thank you. So um, we are actually even carrier and most manufacturers are moving away from the Piston. All together, we're seeing a lot more. TXV So that means if you do have a TXV you can actually hook up to the liquid port and have an accurate head liquid pressure reading.

You can actually check subcool if you have that. um, just. it's important to be aware of this so that you're not confusing you on the situations when you when you don't have that and all you have is your discharge in suction. So let's go into checking charge and cold weather.

Is there anybody in here that feels uncomfortable with accurately checking heat pump charge and 40 weather? Okay, two people. the rest of you feel great about checking charge and heat. That's good all right. So you guys can all leave because the rest of this class is going to teach you how to accurately do it.

But since you all feel comfortable with that, um, you can leave. I've never felt so unneeded and hurt. Um, first thing on here is, uh, not just the thing that you say because you need to be accurate and you need to like make all the Nerds happy online. Read the the manual check manufacturer specs.

No, that's absolutely essential in a heat pump. In heat mode. there's a lot more variance between one model and the next in heat mode than there is in cool mode. So uh, things like the evaporator if it was sized for our climate where it's oversized and does more dehumidification can affect your head pressure quite a bit.

and then things like how efficient the coil is outside. whether you have an older little tiny baby or you have the ones designed for really efficient heat pump really tall stack coil, same tonnage. you're going to have different readings and so manufacturers are really great actually about putting charts either on that back panel or if you open the install manual, even a more thorough chart that can walk you through what your pressure should be in heat mode. So uh, for me, usually typically at the early of the Season I'll snap a picture not of R22 but of a 410A chart like this.

Um, because I can get kind of a general rule of thumb at a glance from a chart like this if it's this temperature outside this temperature inside. General rule of thumb, but we're not going to have exact numbers unless we actually look at that manufacturer. Linux is great. They actually, uh, talk you through how to test it when you need to recharge it, covering the panels outside, they walk you through doing that U when you actually need to add charge um and then train they've they have uh.

also well this is more about defrost but they have step-by-step testing Defrost. They have a demand defrost which is a little different than their carrier setup and then at the same time. uh, plenty of charts for checking heat mode and what to expect on your liquid. And that's another thing.

A a chart like you're seeing right here is for this picture before. so this is discharge common suction where as if you hook up to a Linux the charts that the manufacturer give you is going to be liquid. Also in there they're going to say below this temperature you're going to need to check your charge and heat Above This Temperature check your charge and cool. Anybody know where that common point is? So it's typically 60 to 65.

So if you I want to say to you guys, if you're above 65, let's turn it in cool mode and we're going to set charge and check charge that way, it's probably a little bit more accurate. If you're below 65, let's turn it in heat mode and uh, figure out what we have there. And um so then then next thing, let's talk about some rules of thumbs. Rules of thumbs are just that.

Um, everybody has a little bit differen Siz Thumb point is it'll get you close but not exact and so close is often good enough. If you're doing let's say a maintenance and we don't have a complaint. Close is good enough if you do a diagnostic call and you have a failed capacitor and you need to get the make sure the system is actually operating the way it should Afterwards, we don't have a reason to be suspicious of our charge. Close is not good enough.

When we're doing a quoted repair and we need to recharge our system. Close is not good enough. When the issue is a refrigerant related problem, we need to make sure we actually set that refrigerant exact. But the rule of thumb is really great for letting us know if we're in a safe range.

Let's talk about this first and most common one: Um, the discharge Vapor line being 100 to 100 uh than 10 degrees over ambient. Anybody here notice that that's not true for a long. It's exactly right. If you have check this regularly when you're checking heat pumps, you're going to notice this is very inaccurate unless you've let it run for a long time on a cold day.

And so the issue is is is that on a on a cold day with a refrigerant temperatures as low as they get, you can have a lot of liquid that collects and builds up in the accumulator from the last runtime and you turn it on and a majority of your refrigerant is not actually in circulation yet and so running it for a long time letting it stabilize is key for this particular one. Um, so the 100 above uh, the ambient. So ambient outside 100 degrees discharge. take your discharge temperature right there on the on the suction.

what was the suction line? um and then outside temperature. That's also what they're using on this chart. Uh, they also have the wet bulb dry bulb wet bulb SL dry? Uh. Dry bulb up at the top and you can see the two temperatures at the top.

So it would be more accurate to use wet bulb. find the wet bulb on the chart would be a little bit more accurate than dry because uh, there's a a lot of heat and moisture that's being held, so it's If you account for that, you get a little bit more of an accurate reading. Okay, uh, systems must be frost free and outdoor temperature must be between 65 and 15 and so that is another range we just talked about, but we didn't talk about the low side. If you're trying to go off of rule rules of thumbs.

once you get lower than like 15, you're not going to be. You're not. None of your rules of thumbs are going to really apply and the reason for that is is that you you have to bring the suction pressure so low in order to get it cold enough to absorb heat from a 15 air that you're actually going to change your compression compressor ratio quite a bit. You have hardly any gas feeding into that compressure, but it's still slamming out really high pressure.

on the other end. The inside of your house maybe is 68 and so it's still slamming out a very high pressure. Uh, it still has to produce that same on the side, but we're pulling in a very small amount of refrigerant on that side so we don't have um, as much for the compressor to work with. So it changes compression ratio and this, especially the discharge temperature over ambient.

Those things aren't rules of thumbs, just go out the window. So what do we do when we can't use a rule of thumb and we need to get our charge where it's supposed to be? Use a charging jacket charging jacket. That's great. You have charging jacket, what else? What would be the best? Way 15 degrees.

We need to get our charge right. I Knew this is a good time for breakfast. Up charge? almost? Yeah, way out the charge. Way in the charge right? So install qual repairs things like that.

In very cold weather where we're making significant changes to the charge, let's wait out that's crucial. Okay let's say we come up to a system and we have like an 80 Dee above ambient. after 25 minutes of running on our discharge. Any clue what might be causing that normal indoor temperature? Let's do uh 68 indoor temperature instead of our 100.

We have a little bit lower. That typically means you're overcharged so you have a little bit more refrigerant the compressor is pushing against, but also a lower compression ratio. So you will actually have a higher discharge temperature when the compressor can smash it a little bit tighter. maybe a little less refrigerant coming in initially.

coming right out of the compressor. you're going to have a little bit higher temperature. So when you're overcharged, you're going to see this number come down a little bit. You also, um, will see it go above when you're undercharged.

so it's a little counterintuitive, which is why I'm talking about it, but we have 130 above ambient. We're probably undercharged. The other thing to keep in mind is if you're grossly overcharged, then that no longer applies. If you are significantly overcharged, you're going to have a really high discharge.

Uh, your compressor is just fighting against, so that takes quite a bit. so do keep that in mind if you have a reason to suspect somebody added an extra 10 lbs to your unit. Okay, Liquid line Temperature above indoor dry bulb 3 to 15 degrees. This is approach.

So uh, indoor is the temperature coming across your in your condenser now which is inside. So that's a reference points that you're going to use. Normally with approach we're taking outdoor temperature and liquid line, but with approach in heat mode, you're taking indoor temperature and liquid line. So this is another good rule of thumb.

Another good rule of thumb not listed on here before is that oh yeah, suction line. So this would be hard for us to read on a split split system because the suction line is behind the reversing valve. But on a package unit or an Rtu, you have access to your suction line. So suction line 5 to 15 degrees below outdoor ambient you're in a safe range rule thumb.

So and a lot of these you want to take them together. If you're in a if you have good charge and you you have one of your rule thumbs hitting the Target and you do have good charge, you're probably going to have your other ones hitting the target as well. But if you just have one hitting your Target and the other are way off, we have a problem. We need to do more investigation.

Another one that listed on here is that typically the Um within our range I would say of about 20 and 65 you're going to have 20 to 25 um degree saturation below outdoor ambient. so we have our outdoor ambient. Then it's going to try to drop our pressure so that our suction saturation is 20 to 25 degrees below that so it can absorb the heat. Which means if it's 35 de outside, how cold is our saturation going to be 10 to 15? 10 to 15.

Which means the second it comes on, we're going to see that Frost We're going to see that ice because it's trying to hit that 10 to 15 degree refrigerant level and absorb heat. We're going to see that Frost Right away that's normal and immediately your system's going to be triggered. That, uh, the Def Frost trigger is going to immediately go off and that timer is going to start counting down. You set a timer on your defrost board for how long it notices that we're below freezing before it kicks into to defrost mode.

So uh, in Florida we usually set it for the max which is like 90 minutes so it gives it a chance to run that long even though the sensor is sensing that it's freezing and hopefully satisfy the house and turn off and stop freezing before before it goes engages our defrost. using the charging jacket. the charging jacket fuel piece has a great charging jacket you wrap around unit, strap it down and as the uh heat. So using a charger jacket would be when you turn it into cool mode on a system.

Um, because it is more accurate to check refrigerant in cool mode. So one test that you can do is turn it into cool mode and use a charging jacket. Have you guys anybody here not seen a charging jacket? Oh okay. I Wow.

Okay I should have put a picture in here. my bad. But basically it's this black bag this charging jacket that goes over your condenser and wraps down the sides a little bit so that when you turn it in cool mode the hot air circulates back into the condenser and then it brings the pressure up a little bit more raises the temperature. that air.

It keeps that circulation so you can stimulate a simulate thank you a cold somebody twitch and I realized what I did simulate a a hot summer day. We got that hot air circulation and you watch your head pressure come up to what you would normally see in cool mode. uh and then you can more accurately check refrigerant charge in that way. And like I said, Linux has even like a breakdown description, they don't want you setting the charge in heat mode.

They don't even want you trying. So like if you got to adjust the charge, wrap it. They talk about wrapping it in cardboard and making adjustments as your head pressure comes up to a normal level. That's it for today's class.

Um, I did want to take any questions that you guys have or scenarios that have been issues. We're already at our 30 minute limit but we can keep going with questions or what would be a good tempter split. You'd expect to see great question so that that's also a huge range because load affects that so much as out in outdoor temperature comes down. you can't produce nearly as much because your compressor is being fed such a low volume of vapor and so um, you're going to see a huge swing.

I've never seen anybody list it as a rule of thumb because of that, so probably forget about that. I've seen like 35 degrees and then I've seen like 10 in testing it so well the 10 degrees was low and charge. I've never actually tested something when it was about 10 outside. it's never gotten that here so that one was more low in charge.

but you probably will never see something that low with a decent charge here unless you're working in North Florida possibly and you got 10 degrees outside, then you'll see some of those extreme changes. There is a general rule of thumb of like 60 40 to 40 to 60. um, condenser saturation above ambient. So your indoor is now your condenser ambient.

but again, that's another thing that ranges quite a bit. So when we're talking about rule of thumbs, I guess I is important that I actually do mention this. we're checking the charge. It's going to be be really important that our system is maintained clean and operating normal before.

We can trust the rule of thumb, right? So if our condenser coil is clogged at all, like even a little bit, we get away with it in the summer. But when you go into cool mode and you got to absorb heat through that coil and it's 30 outside, that's going to be a real problem. That coil is going to want to freeze outside. It needs perfect air flow across that coil.

So um, that's a a thing you watch for I will sometimes spray a coil when it's cold outside just to make sure I don't see dirt coming through that coil and we're not uh, being affected by that. And also the water is around 70 so it allows me to bring the temperature up a little bit and see something a little more normal for a second. Feel better about myself. The other side of that is your evaporator coil is a much smaller coil than your condenser.

so it's very affected by your indoor blower and it's very affected by being dirty as well or your filter. We're already dealing with a smaller coil, so it's going to be higher pressure. same amount of refrigerant is trying to condense in there. Um, but we have a lot higher pressure typically.

So if your blower is set for a low speed because somebody wanted to dehumidify really well in the summer and so we just dropped it down to a low speed. you could run into issues in the winter with going out on high head, uh, really high temperatures across that coil or um, the filter starts getting dirty and the combination is way too much and we're going out on a high head pressure. So keep in mind your blower, speed, your filter, and then lastly, if that coil is dirty one, it's pretty disgusting that coil is going to get very hot, You're going to have like 140 on the surface of that coil, and it's going to bake whatever nastiness is in in there, and typically you're going to smell it. Uh, so that's nasty.

But on the flip side, of course, a dirty coil is going to create really high head pressure as well, something that maybe 30% impacted. We went through the summer fine, we never noticed it, we didn't care, and now in the winter we're going out on high head. So keeping those things in mind, air flows crucial both outside and inside. Thanks for asking that split question I Forgot all about air flow? Great! So uh, if you didn't hear any anything else, you heard that if you read the manufacturer specs, they give you some pretty great information on heating.

They give you more information on on the heat and checking it and charge and uh, rules of um that can help you like practically than they do on the cool because they understand that uh, heat pumps are a little surprise to technicians more often than than cool is right. So great. Thanks thanks for watching. If you're willing, give this video a thumbs up and drop us a comment.

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