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There's a whole process for that for the smart probes deal, here's where you go! I've created a special short link that you can use. It's HVAC our school comm forward, slash smart promo HVAC, our school comm forward, slash smart promo, he's creepy in a good way, Brian or here we are again on the HVAC school podcast thanks for listening. This is the podcast that helps you remember some things that you might have forgotten along the way as well as helps you remember some things you forgot to know in the first place, but, let's be honest, there's a lot to know in the HVAC industry, and there Are some segments that many of us don't see very often, but when they pop up we're expected to be able to work on and fix the equipment and one of those types of equipment is water source, heat pumps? A lot of people work on geothermal, which is a form of a water source heat pump and then in other places they actually have open-loop systems. A lot of different types of water source, heat pumps out there and Eric Mele has worked on a lot of them.

Eric is a technician down in South Florida, he's been on the podcast a couple times: smart no-nonsense technician and he reached out and said: hey: let's do a podcast on water source heat pump. So that's what we're gon na do the introduction to water source heat pumps all right? Well, thanks for coming back on the HVAC school podcast, for I think your. What what is this? Your fourth time now Eric? I'm, not sure I think it's, the third or fourth? Third or fourth, okay: well, thanks, anyway, for coming back on taking the time to do it all right, no problem, okay, so busy Florida summer, both Eric and I are dealing with the Florida summer, although you're off of work and it's 5:30. So that means that either you're not too busy or you just have a really good work schedule set up with at work.

You do so, which is it I'm just not on call today cuz, I was on call over the weekend and I was getting called out. That was fun me too. I've been telling everyone this, but I actually worked until 2:00 a.m. on Saturday.

Nice, proud of me. I'm very proud of you very proud of you kidding. That's what I was looking for today, we're talking about water source, heat pumps and I think we're gon na probably do a couple different podcasts on this, but to start with, let's just go through what is a water source heat pump, because I think some guys may Have never seen one or wouldn't know what to expect if they did see one so they're pretty common around my area, some guys will call them geothermal x' if they're used to it in that application, which it's the same unit. I don't see geothermal applications here, but you're, basically using water to transfer heat to or take it out of a lot of guys like to call it the condenser down here in Florida, because we don't use heat mode hardly ever, but that's basically it so you're using Water and a heat pump in the same way that you would have previously used outdoor air exactly and you have to have that water pumped to you somehow very common down here - is the building.

It's gon na be like a condo building and the building is gon na, have a pump and they're gon na deliver the water at the appropriate temperature and the appropriate gallons per minute for the equipment to function properly, or at least that's what they're supposed to do. Well, that actually brings up an interesting question. We don't do them too much, there's not as much in Central Florida, but we had one of these just recently where we showed up - and that was sort of the conflict is like all right, so the association is responsible for delivering it and then you're just responsible For the equipment, that's typical yeah, that's typical of like a condo building. They'll have a company that takes care of that they hire to take care of their side of the equipment and they're just going to supply the water to the unit and it's the owner's responsibility.

The the whole entire unit is their responsibility, the owner of the unit. It is kind of a tricky thing because you can get into situations where you'll get caught up by a customer and it is possible that it's just it's a building problem. Usually, the buildings are pretty good about notifying, like if they're gon na be doing a bunch of work to their system and they're not gon na be supplying the water for a time. Usually they try to notify everybody, but sometimes stuff happens.

Sometimes it's over the weekend management company's not there, and this person happens to be the end of the run and they're getting affected first before everybody else finds out, so you'll be the guy to tell them all right, and so that would be in general. What are you seeing like cooling towers on the roof, or how do they actually remove the heat from the water, so you'll see more commonly in my area, you'll see a cooling tower on the roof or on the ground I mean wherever they want. To put it. Basically, a cooling tower or you'll see water to water heat exchanger.

I've seen him running off of wells before wasn't very common, but I've also seen him running off of seawater, so we'll have like a titanium heat, exchanger and they'll actually use seawater in a heat exchanger that way, and that's completely external to your heat exchanger in your Unit so that would be closed versus open loop, it's just probably beyond the scope of this podcast we're just gon na try to focus on the actual units first and then we'll move on to the rest of the stuff. Okay sounds good. One thing I do want to say, though, is that, if you're not close to the sea, it's very inconvenient to use seawater for that purpose, pretty much if you're in like Oklahoma or something you're, not gon na see too much of that alright. So let's talk about how the unit actually works, then what are the different components inside these units? So the only thing that you're not gon na be used to is you're gon na see that there's gon na be two water lines going to the unit and there's gon na be that heat exchanger that we've already alluded to other than that it's in function.

It operates the same as a heat pump, so cooling mode, the heat exchanger is your condenser and in heating mode, the heat exchanger is your evaporator, so technician walks up to this thing, the entire thing is going to be inside. So in a condo, it's gon na be sitting in a closet somewhere, so we would traditionally think in it like a split system type of setup. We would think alright. This is the air handler, but in this case you're actually gon na have the compressor the heat exchanger, the evaporator /, the condenser.

That's your air coil and a reversing valve all inside this one box, most commonly yes, but there are bigger commercial-style units. Some of them are horizontal mounted in ceilings and there are even split water source units and I've seen small split water source units. You'd. Look at it at first thing like what the heck is this thing, then why is there refrigerant lines and oh there's an air handler over there? You will see that from time to time, but most commonly it's over top of a water heater in a closet and, like you, said, everything's right there, it's a packaged unit got it.

So what are some things that you need to be aware of with these units that may be unique to these types of units? A lot of guys in this area? Don't really understand heat pumps, so we can go over that really quickly. You're gon na have a reversing valve so basically you're just changing the flow of refrigerant to make your evaporator and condenser switch places, and typically every water source heat pump. I've seen they energize the valve to be in cooling mode. That's not gon na say everyone will be like that, but everyone I've seen so far got it.

So it uses typical, Oh call that we would use for a standard heat pump. Exactly and do these ever have auxilary heat as well. Yes, there are applications, will have electric heat or even reheat for humidity control, there's some buildings where they have any way to put heat into the water for heating mode. So if you start running a bunch of these in reverse cycle, heat mode, you're gon na get your piping temperature really low to where the units aren't going to operate properly, and you could have condensation forming on your water piping, which would be bad for places where There's concealed piping, you don't want water damage, so there are some applications where they have electric heaters.

These, like doc, Peters, mounted up the unit, so you're saying in some cases, they're going to have a way to keep up the water temperature. So that way, it's gon na heat, better in heating mode, which is going to increase the system performance. But in some cases that water temperature is gon na drift down with the outdoor temperature and with the fact that you're running multiple of these heat pumps on it and then that's gon na impact. Your heating capacity.

At that point, I'm more similar to what you see with the typical heat pump, then yeah, and they don't have usually not seen a defrost board in one that there's really no way to defrost. Because your your operator, you can't really change a thing about your water flow or anything to reliably run it down that low. They usually have you look at the manufacturers performers. They have like a minimum water temperature that they want you to be putting in there or you're gon na have pumps.

How can you tell if you have what you're supposed to have from a water standpoint, because I mean obviously if water pressure, I guess, but then there's also flow rate. So how can you tell if you have the flow rate through your heat exchanger that you're supposed to have? So if you look, it's not the easiest way to tell, but if you look at I'm gon na say Bosch because they put a lot of information online. You can look at like their performance charts and it's gon na tell you what you should be getting as far as a differential temperature on your water side and heating or and cooling. Now, that's a course in a perfect world where your heat exchanger is clean.

That can give you an idea, you can get old school and you can fill a bucket while you time it. So the easiest way to do that would be to use one gallon bucket that you put inside of like a larger five gallon bucket and take the outlet pipe and disconnect it. Hopefully they used easily disconnectable hoses and then you can just time how long it takes to fill that 1 gallon bucket or if they were nice enough. You might have a way to actually check pressure differential and then you'd have to reference the manufacturer's information to see what that's gon na translate to in gallons per minute.

But some of those pressure drops can be like less than a PSI. So how good's your resolution to actually confirm this, your instrumentation? What tool would you use for that? You would use any sort of gauge that you can read water pressure with you'd want some good accuracy and there's these fittings. It's called like a Pizza, DAP tur, like the first name Pete, and it looks like the tool you use to inflate a football or something it's like a little needle like tool, and you can put it if you actually have those available they're on a lot of The stainless steel hose kits but they're, not on everything the majority of stuff isn't gon na have a way to test pressure. But if you do, you can do it that way.

So what do you find yourself doing? Most often just sort of checking the temperature differential across the heat exchanger, then yeah. You check your inverses out and also how hot is your liquid line? Getting is your liquid line getting crazy hot because you usually have 85 degree water going in and if you're getting a really high split on your water like more than 10 degrees, it's most likely gon na start. Looking like a flow issue like a water flow issue right, but you can't have the multiple problems going on where you have scale building up inside of the pipe which is gon na act as insulation. So if it's scaled up pretty good, you might not see a big difference in temperature, but you'll have a really hot liquid line, so that with a scale, is also gon na reduce your water flow.

At the same time, I had one recently that was really scaled up and you have to flush it out with acid or you generally connecting gauges to these. I imagine the charges are pretty critical on them. A lot of the Bosch which are pretty common are capillary tube and some of them have total system charges in the teens of ounces, so less than two pounds. So you want to minimize that for sure they're all charged by target superheat.

So when you said checking liquid line temperature, then checking temperatures would probably be the way to go. Do you know what a typical condensing temperature over water temperature would be like? What would you normally look for there? As far as an expected, it's gon na depend on your water flow and your water temperature a lot. So it's really hard to say you shouldn't see anything crazy out of the ordinary. Obviously, if you're getting less water flow, you're gon na get a warmer liquid line and it's hard to give you exact numbers, you kind of just got to refer to the manufacturers.

Literature. If it's looking crazy out of the realm yeah, it's something that you'd have to just use some common sense, I'm thinking in terms of like for an inefficient air condenser. You would think that you'll have a 30 degree differential between the outside air and the condensing temperature. But in this case I imagine it's going to be more efficient than that.

Is there like a normal expected liquid line temperature in comparison to the water temperature under normal conditions? I mean because in AC it's probably gon na be like 5 to 10 degrees. The liquid lines can generally be about 5 to 10 degrees warmer than the outside temperature. On an air-cooled system, yeah you're gon na see about the same, like I said unless you like, some of them run on the ragged edge of water flow. But if you're starting to see liquid line temperatures and the hundred 110, you might want to start looking at your water flow or the possibility of scale building up.

Okay, that makes sense. Well, then, that gives you something to go off of, and then another good thing to look at would be your discharge line temperature because you have the ability to do that on these, and so, as you start to see, discharge line, temperatures increasing, then that's also an Indication of problems exactly and you'll start to really drive your suction pressure in weird ways. If your head pressure gets too high because of the fixed metering device, so it's actually a capillary tube, not a piston and actual capillary tube. I have never seen one with a piston, but I'm not gon na say that one doesn't exist.

I mean the capillary tubes gon na meter, the refrigerant the same, both directions and not have any mechanical fitting or moving parts. So plus it's probably a lot cheaper. That's probably the main reason they do it, but you can run into as well getting that restricted because it's a cap tube they usually have a strainer before it. If you're familiar with dealing with strainers, I've seen compressor change outs, where people really didn't do good practices and you go back and it's got super high head pressure.

But it's just a clogged up. Strainer we'll talk about that real, quick, so best practice. There is what well just basically don't get a bunch of crap in the system. Okay, it's good that you mention that, because the problem I find, though, is trying to flow nitrogen through a cap.

Tube system is kind of problematic cuz. Your cap tube really restricts the flow regulators and can make it really hard to braze. So I mean I'm not gon na say this is the best practice, but a lot of times I'll flow, nitrogen right up into the point where I'm about to braise and I shut it off so then there's still mostly nitrogen atmosphere present and then braze, real, quick And then start flowing it again I mean probably not the most ideal thing you can do, but you got to do what you can yeah. I would say that that is a definitely unallowable workaround.

I've had a couple. People tell me that, even at the 2:00 to 5:00 cfh level, in some cases, it can be really hard to seal up a joint, and so, if you're struggling with it, because you always have this issue of flowing nitrogen, you have to flow it from somewhere to Somewhere and in this case, like you said it sometimes it's hard to get that flow so low with a flow regulator, because of that cap tube, restricting it and say yeah, you just do the best you can and then you shut it off real quick finish. Your braise and then keep as much nitrogen it as possible. Again, a lot of the issues that occur with scaling are a combination of poor practices where they're leaving the system open for a significant amount of time and then also using way too much heat as well.

You just really smoke and stuff if you use good practices as far as good heat control and you've kept nitrogen in it, you purged it with nitrogen beforehand. In fact, I would argue that the purging of nitrogen beforehand is probably just as important, if not more important than the flowing of nitrogen, when you're actually brazing so to get the atmosphere out of it in the first place is probably even more important. Yeah, the smaller the systems, the easier they're affected by contaminants, because they're not getting diluted near as much as if you had 50 photoline set in a big liquid line. Dryer.

Usually these things don't even have liquid mine dryers, so the smaller units they just have that strainer that they rely on and there's not any sort of real room to add them. If you wanted to. Some of these are really small and you're talking about pulling the entire electrical section out of the way just to access the compressor, in some cases, just to get the cover off to check your windings there yeah it's tight, really tight. I want to double down on this whole idea of a cap tube, though, because I think a lot of AC Tech's may have really never seen a capillary tube, and so it's just a tiny piece of tubing.

The reason why it works in this application for a heat pump is because everything is all in one spot. The reason why we have to have two separate metering devices in the case of a typical air source heat pump is that you have one part outside and one part inside, and so they have to have separate metering devices. But in this case you can just have the one and it just switches the direction of flow. One thing that I've seen in like refrigerators and small refrigeration that have capillary tubes is, if you get a restriction in the capillary tube, though usually, if you just cut out that really small section right at the beginning on the one side that is restricted.

Usually that will eliminate it. Have you ever done that in this type of application I have not, but I like I said, usually I found that they put a strainer and I cut the strainer out and put a definitely if I cut a strainer out. I do my best to find a room to put a buy flow dryer in right, and it would need to be by flow yeah. Indeed, do you ever see these with an expansion, TXV or constant superheat valve, as I like to go on when they start to get a little bit bigger, they're gon na have a TX v or even the smaller train ones, for some reason Trane likes to do It - and they only have one TX v so in heating mode, your refrigerant flowing backwards through that TX v and there's no other metering device, but that's how they do it.

So where do they place the bulb so that it actually works? I don't understand what the bulb would go. I guess right at the compressor, then yeah, you see it right at the compressor yeah, so it would be on the other side of the reversing valve on constant suction. Then that makes sense exactly. Is there like a water pressure, switch or some sort of proving switch on these as well? Sometimes they've used them intermittently, sometimes they'll have water proving switches on them will just be a little switch between the inlet and outlet piping and they'll be small piping connected to it.

So it can see that pressure differential, not really super common, but I've seen them, and then they have three sensors a lot of times too on the newer stuff. Obviously don't want to freeze up, especially your heat exchanger. You don't want to freeze it up and rupture. It right that'd be not good.

I can imagine in like a condo or something rupturing, your heat, exchanger and then having it flood out a condo. I think you would probably just ingress water in your refrigerant circuit, because the outside is gon na be steel on the inside is gon na, be copper, but that's not guaranteed right. So right yeah, I guess okay, all right to be more likely to collapse. Inward! Oh another thing is these: do function with counter flow right where the refrigerant and the water flow in opposite directions from each other.

Yeah they're set up to be counter flow, but I'm not saying this is a good idea, but you come across them that have been running 10 15 years and the water is not flowing through the right way. So I'm not sure it makes the biggest difference in the world, but it's always a good idea to follow the instructions and send the water through how they want it yeah. I wonder why yeah that's an interesting question. Why does counter flow really matter? I mean you kind of always heard what helps with heat exchange, but why would it help with heat exchange? I don't fully understand that.

I guess I've always read it, but you'd be having the biggest temperature difference possible. You'd have your hottest, refrigerant meeting your coldest water in cooling mode, so maybe it speeds up the transfer because of the difference in temperature. I've not seen one not run because of it, where I could ever attribute the fact that it's not running because of it usually you're. Just like the times.

I've caught it to some one of the times was changing one out and putting the new one in, because the other one was dead and I put the new one in pipe. Just like the old one and yeah one go to check the water temperature and it's like okay, the water's going backwards, got to switch these hoses, which usually isn't a big deal. So it's usually pretty easy to fix. But one thing to be aware of too, though kind of secondary to these units is sometimes they're on some really crappy piping, so be very careful when you're messing with the piping, because that is a lot of potential water.

That's gon na come at you really fast. If you are to break a pipe, so that's something to keep in mind. Some of them are piped into PVC. They're not supported very well.

You could easily snap a threaded fitting off. I don't want to scare people too much, but definitely be aware of it, and they always have shut off valves right there right. Well, that's the thing though it's usually the shut off valve is threaded on. So the threads are the weakest part of a piping system.

Right, so you have an issue there with unsupported piping and you snap, your shutoff valve off. That's gon na be a bad day. Have you ever thought about like some sort of an emergency like? Will there be like a sharkbite fitting with a cap on it? They could be like your emergency, I shove it over the pipe tool or something the problem is, is what are you gon na be? If you have some sort of flexible tubing and a hose clamp, you can do it. But what are you gon na be trying to snap it over like if you just snapped off just the threads of a male adapter like a PVC, male adapter, let's say like worst case scenario now the other part of PVC fitting is much bigger than the piping.

So you'd have to have like a piece of clear tubing with a hose clamp, that's connected to a ball valve, because you're not gon na get that thing on there, like as a cap, you're gon na have to get it over with the valve open, tighten down The hose clamp and shut the valve off I've heard of guys making stuff like that and keeping it on their truck now. Did they remember to take it on the call with them? I don't know I've never heard of anybody using one. It was always after somebody did something that guys got nervous and tried to make something to make themselves feel better, but I've never heard of anybody actually doing it. It's funny because, as a technician, I probably wouldn't have cared I'd, probably like.

Oh, they would suck, but I'm listening to you with my owners, mind and it's like it's complete terror like holy crap. I can just imagine that happening. It actually did happen to us once with a water heater, a guy had a built-in air handler over top of a water heater and he was working on it and then he dropped a panel or something and it cracked off the water main going in it. Just flooded the house, while he was trying to find the shut-off in the house, but it's even worse, with a condo because now you're damaging other people's property.

In addition to it, which is no bueno as they say yeah, you don't want to be that guy and at that point in time, you're gon na have to go very quickly, find where to shut the pump off like just find the pump and shut it off. But that's easier said than done right. Is it on the roof? Is it on the ground? Are there more? Are there booster pumps yeah? I mean, I guess the truly prepared would already know where it was before you started working on it, but that's just not realistic. In most cases, no, it's not at all realistic to get to the building and be like where's your pump set.

Why, in case, I break a pipe they're gon na be like leave now, don't even photo that you're banned from our building. That's funny. I had a customer do that essentially that same thing to me the other day and some refrigeration project we were doing. I was just asking questions because I get paranoid, especially when it's something that I don't do every day and they had ordered the equipment.

And so I was just asking him questions about what they ordered, making sure that they got the right defrost in it. And everything and they got like ticked off with me - I forget the exchange, but it was a funny exchange. They were like well. Is there a problem and I'm like no, I'm just wanting to make sure that everything is correct and she's like if you're having to ask all these questions? Now I'm worried, you know it's like you worry people when you try to be too prepared.

Yeah. I've noticed that about people too, like so you don't want to hear that they want someone that already knows everything, yep yep yep, that's how it goes all right. So anything else we're missing here on water source, heat pumps, so it needs generally about between 85 degrees and 60 degrees is rule of thumb as far as the water that you want coming in to them. If you look at performance, charts they're all over the place, your specific application will dictate that, but at least where I'm at like the practical water temperature, they can maintain as usually around 85.

If it's a little higher, it's not a big deal, but that's usually the set point I imagine in other parts of the country and maybe they're just not as popular in other parts of the country, but where groundwater is well below sixty degrees. That may make it a little more challenging as well. They probably factor it in and slow the flow down, because if you go to Bosh's site and look at the performance chart for the unit, it's gon na tell you what its gon na do with a given water temperature that plays into it a lot. I mean a fixed metering.

Device is actually pretty good in this application, because you're condensing temperature remains fairly constant. If the building is supplying water properly, they have other ways they can manage that yeah. So then, the only other thing that changes over time would be the scaling inside, and so you separate it from the water supply then and actually run acid into it and just kind of drain it into a bucket sort of a thing. Is that how that works? Usually, what you do is you recirculate it into a bucket like a five-gallon bucket works good, you get a special acid pump for it and they sell your supply house which should carry it or be able to get it and they sell descaler.

They actually sell a pH indicating descaler that I used last time. I had to do it and it's pretty neat because it changes color once it's neutralized, because the scale actually neutralizes the acid. So if it turns purple, then it's completely neutralized if it's still working. So you have to keep adding it until it's green and after you add so much, you have to just flush with fresh water and start over.

It was three times on this particular one, oh well, how do you know when you're done? I mean? How can you tell on this particular one it's color indicating, but on other ones, there's you use little test strips you dip the test strip in the solution. I got that part, but as far as the knowing when your acid is neutralized, but how can you tell when there's no more scale or or is that what you're saying that's what I'm saying the scale neutralizes the acid? So if your acids, not neutralized and you've, been running it through for a while, they say 30 minutes like after 30 minutes of running it through. If it's not neutralized, then you're free of scale, because it just melts it all out of there. I see so eventually we'll neutralize it if there's still some in there, and so, if you go through your first that changes color, then you got to do it again and if it doesn't again, then you get to do it again.

I get what you're saying it makes sense with this particular product. You could add it three times before you had to flush it with fresh water and start over. It's like a twenty to one ratio, one part acid for 20 parts, water, I believe at least this product was, I think, that's it for this one right. That's our intro to water source, heat pumps, yeah that should cover that and then we'll definitely get together soon and do some more podcasts on the rest of the system.

I don't know how many parts we'll have to do see how much we ramble on about it. Right sounds good man all right thanks Eric appreciate you all right, thanks for having me back again soon, all right. Thanks for listening to the hvac school podcast, I appreciate everybody who participates by listening to the podcast by commenting on YouTube, subscribing on YouTube, that's something I got a lot of content going up on YouTube now, a lot of short videos just describing certain things. I'm gon na be doing a lot on schematics and diagrams coming up, because I get a lot of demand on that and I figured out some new ways to demonstrate these sorts of things in video.

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The other day to me is, I went into the library, and I asked the librarian if they had any books on paranoia and she looked at me and said: they're right behind you all right. Thanks for listening, we will talk next time on the HVAC school podcast. Thanks for listening to the HVAC school podcast, you can find more great HVAC our education material and subscribe to our short daily tech tips by going to HVAC our school comm. If you enjoy the podcast, would you mind hopping on iTunes or the podcast app and leave us a review? We would really appreciate it.

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