Hotspot FPH AC heat reclamation pool heater - a review!

[Belikin]

sorry, I'm not any help with an installer in the Tampa/Brandon area. I expect that the guy who did mine up here in Jacksonville (The AC portion) would come down that way for enough money.... but heck for enough money I'd take a swing at just about anything!

What I really came to this thread to do this morning was to brag a bit for anyone who's wondering how well the system works. I've been using AC irregularly up here in Jacksonville over the last couple weeks and as of this morning my pool is officially pronounced "swimmable" by the wife at 79 degrees. She'd prefer 85 or so and I predict we'll get there in the next week or so. I don't know ANY of my neighbors who are swimming yet, and I just got out of my pool from my morning dip.

 

[tampapools]

I've been using AC irregularly up here in Jacksonville over the last couple weeks and as of this morning my pool is officially pronounced "swimmable" by the wife at 79 degrees. She'd prefer 85 or so and I predict we'll get there in the next week or so. I don't know ANY of my neighbors who are swimming yet, and I just got out of my pool from my morning dip.

any idea on how much it warms the pool per day? How many hours the ac is running? size of ac and pool?

I haven't yet had an ac company say they will do it, most either outright say they won't, or they think it won't work because modern ac units are too efficient and don't generate enough heat.

 

[Belikin]

any idea on how much it warms the pool per day? How many hours the ac is running? size of ac and pool?

I haven't yet had an ac company say they will do it, most either outright say they won't, or they think it won't work because modern ac units are too efficient and don't generate enough heat.

I have a (new in 2020) York, 5 ton (I think) AC.
Looking at my energy usage for the last week in Nest its been running about 2 hrs on average. A couple of days it's been as much as 4 hrs.
Hotspot told me that with my AC size 4 hrs of run time a day would get me and maintain my temperature with overnight loss etc.
I'd say I get somewhere under 1 degree a day if I had to guess but honestly I don't pay that closely attention at the specific level, I more look every couple days and see that it's slowly rising.
I'm still hovering about 79 degrees at the moment but we've had some colder weather that has reduced my AC runtime.
As for AC folks, I had to call around a lot and finally got a small business owner who was willing to do it for the experience and potential ability to do more once he knew what to do. And he still had me sign a waiver acknowledging that his modifications might void the warranty in the eyes of a York tech, but that he'd be willing to do any repairs under York warranty without mentioning it.

ETA: I've done a little more math and retrospective look at my AC usage and temp logs. It looks like 2 hours of run time on my efficient York AC is enough to maintain the current temp with overnight evap loss but it doesn't look like it's enough to raise the temp further. I'm still stuck at about 79 degrees at the moment. My neighbors pool however is mid- 60's. Last spring I hit a wife swimmable temp of 86 by late march and stayed there throughout the rest of the year until we stopped swimming around Halloween into early November this last year.
Hope that's helpful!
If you'd like to talk to my AC guy, DM me and I'll send you his info. He's done several more systems since mine, but all up here in the NE Florida area to my knowledge.

 

[newpoolj]

Question for any Hotspot owners: do you run the Hotspot with lower GPM, such as when running a pool cleaner? The hotspot manual says it requires a min GPM (45gpm for a 5 ton unit), but my 360 pool cleaner needs about 20 GPM to run right. How is anyone else dealing with this? Any ideas for maybe turning the hotspot off while the cleaner is running?

 

[tampapools]

Question for any Hotspot owners: the instructions call for a min GPM (45 for a 5 ton unit). I have a pressure side pool cleaner though which needs around 20 GPM to run. How do you deal with the GPM potentially being lower, such as when running a cleaner? Any ideas for temporarily disabling the hotspot while the cleaner is running?

Just get a Dolphin E30 and toss out the suction cleaner. It's gross to suck up organic stuff and have it sit in the pool filter anyway. They break down and now you're swimming in frog and ant particles. At least, that's what I'm telling myself to justify the $800 robot =)

 

[newpoolj]

Just get a Dolphin E30 and toss out the suction cleaner. It's gross to suck up organic stuff and have it sit in the pool filter anyway. They break down and now you're swimming in frog and ant particles. At least, that's what I'm telling myself to justify the $800 robot =)

I'd consider a robot for the future, but my 360 does a decent enough job I don't feel the need to replace it just yet.

 

[riny]

Question for any Hotspot owners: do you run the Hotspot with lower GPM, such as when running a pool cleaner? The hotspot manual says it requires a min GPM (45gpm for a 5 ton unit), but my 360 pool cleaner needs about 20 GPM to run right. How is anyone else dealing with this? Any ideas for maybe turning the hotspot off while the cleaner is running?

IMHO the FPH installation should always include a pressure switch. The body has a port for one and the wiring diagram shows where to put it, but they call it optional. The problem is that if the flow rate is too low then the water in the exchanger will heat up to the point that it can no longer pull heat from the AC. This will cause the AC to overheat and shut down.

With a pressure switch, low flow will cause the power to the FPH components to be interrupted, and the AC will revert to normal operation. This will protect you from ANY situation where the flow can dip below the FPH requirements, including your cleaner, pump failure, maintenance, etc.

I used this switch. I see you also have a FlowVis so you can follow the same procedure I did: adjust your pump speed until your FlowVis reads 45gpm with a normal load, then turn the dial on the switch until it just clicks. Test it a few times, turning the pump speed up and down, with a meter on the switch contacts to make sure it comes on and off as you'd expect. Then wire the switch up according to the diagram, and that's it. The FPH controller will still come on when there's low flow, but it won't be able to activate any of its components and so the AC will continue running normally.

Of course you'll also want to set your pump's normal speed to a slightly higher flow rate than the minimum so that your FPH doesn't cut out if you have a dirty filter or some other temporary pressure drop...

(Final note: the FPH manual says you need a 3/4" NPT adapter for the flow switch port. On my FPH it was garden hose threaded though. I asked them to verify and correct the manual if necessary, but you should double check before buying an adapter!)

 

[newpoolj]

Great info @riny - thanks! I have the same 1-5 PSI flow switch. I just tried this and unfortunately it still closes when my cleaner is running (around 20gpm). I might try a 1-10 PSI Tecmark switch and see if that's any better.

Edit: Yesterday I received a 1-10 PSI Tecmark switch which I hoped would be open when my pool cleaner is running at around 22 GPM, but unfortunately the switch would only open when I lowered the GPM to around 15 GPM. Since that's still not enough flow for the Hotspot FPH, I plan to install a relay that disables the FPH when my cleaner is on.

 

[Belikin]

Good Info from Riny and I agree with the pressure switch. In my case, I installed at pool build so i just included a single speed cheapo pump dedicated to the FPH cooling flow rather than have it based off of my VSF Intelliflo.
I agree on the robot as well. I'm set up for suction cleaner but the robot does the job perfectly well and at this point, i much prefer it over the suction side cleaner.

 

[newpoolj]

I finally got the Hotspot running the other day, but the initial impression was underwhelming, leaving me wondering if we have the system setup correctly. I should caveat by saying that it was only 73 degrees outside when we did the HVAC install and tested things, so while we had the AC running to test the system, it wasn't that hot in the house.

I was expecting the water temp to be noticeably warmer as it entered the pool and for the PVC coming out of the FPH to be measurably warmer, but it wasn't. My HVAC tech talked to Hotspot today and they said the water should only be heated 2-3 degrees at a time, but based on this video I was expecting it to be measurable through the PVC. We did notice a temp difference of about 40 degrees between the copper going in and out of the FPH, so some heat seemed to be lost, it just wasn't noticeable from the outside. Maybe it's just because it's not that warm out yet, or because the pool water is still quite cold (68 degrees)? Any thoughts on what might be happening or what I should expect at this point?

 

[riny]

I finally got the Hotspot running the other day, but the initial impression was underwhelming, leaving me wondering if we have the system setup correctly. I should caveat by saying that it was only 73 degrees outside when we did the HVAC install and tested things, so while we had the AC running to test the system, it wasn't that hot in the house.

I was expecting the water temp to be noticeably warmer as it entered the pool and for the PVC coming out of the FPH to be measurably warmer, but it wasn't. My HVAC tech talked to Hotspot today and they said the water should only be heated 2-3 degrees at a time, but based on this video I was expecting it to be measurable through the PVC. We did notice a temp difference of about 40 degrees between the copper going in and out of the FPH, so some heat seemed to be lost, it just wasn't noticeable from the outside. Maybe it's just because it's not that warm out yet, or because the pool water is still quite cold (68 degrees)? Any thoughts on what might be happening or what I should expect at this point?

I think that's reasonable, especially if your house isn't super hot.

IMPORTANT NOTE to start: if you're using your hand to test whether something is hot, always use the back of your hand or the backs of your fingers. Never test for temperature by grabbing, wrapping your fingers around something, or using your palm or fingertips. Look this up if you don't understand or don't know why.

With that out of the way... I think you did the most important test, which is the difference in temperature between the copper going into the FPH (which should be insulated) and the copper coming out. If it's hot going in and cool coming out, then that heat has to have gone somewhere. Even if it's not noticeable immediately, it's going into the water and will heat your pool over time.

I wouldn't expect you to register a difference on the outside of the PVC unless it's really hot indoors and it's been running for a while. The IR camera in that video is picking up the difference but you can't tell whether it's enough to feel on the surface. It's definitely more of a slow heat, and it works best if you leave it on all the time so it maintains the temperature, rather than heating the whole pool from cold. (Which it will do, but it will take a while with healthy AC use for it to happen.)

That said though, I definitely felt warm water with my hand in front of the return while it was running. Maybe you have a longer distance or it will just take more output before you start to notice the difference.

 

[Joshii]

I finally got the Hotspot running the other day, but the initial impression was underwhelming, leaving me wondering if we have the system setup correctly. I should caveat by saying that it was only 73 degrees outside when we did the HVAC install and tested things, so while we had the AC running to test the system, it wasn't that hot in the house.

I was expecting the water temp to be noticeably warmer as it entered the pool and for the PVC coming out of the FPH to be measurably warmer, but it wasn't. My HVAC tech talked to Hotspot today and they said the water should only be heated 2-3 degrees at a time, but based on this video I was expecting it to be measurable through the PVC. We did notice a temp difference of about 40 degrees between the copper going in and out of the FPH, so some heat seemed to be lost, it just wasn't noticeable from the outside. Maybe it's just because it's not that warm out yet, or because the pool water is still quite cold (68 degrees)? Any thoughts on what might be happening or what I should expect at this point?

If the condenser fan is off, and the AC air going into your house is cold: it's working. It will take ~2 hours of continuous AC run time before you will notice the difference in water temp coming out of your jets.

 

[Joshii]

Question for any Hotspot owners: do you run the Hotspot with lower GPM, such as when running a pool cleaner? The hotspot manual says it requires a min GPM (45gpm for a 5 ton unit), but my 360 pool cleaner needs about 20 GPM to run right. How is anyone else dealing with this? Any ideas for maybe turning the hotspot off while the cleaner is running?

@newpoolj I run my FPH with low GPM. I don't know what the flow is, but I usually run my VS pump at ~350 watts.

 

[newpoolj]

Thanks for the responses @riny and @Joshii !

If the condenser fan is off, and the AC air going into your house is cold: it's working. It will take ~2 hours of continuous AC run time before you will notice the difference in water temp coming out of your jets.

Good point about cold air in the house! My AC tech is coming again on friday to adjust the refrigerant so I'll be sure to check that. Thanks for letting me know about ~2 hours too. Why do you think this is?

@newpoolj I run my FPH with low GPM. I don't know what the flow is, but I usually run my VS pump at ~350 watts.

Good to know. It occurred to me, the FPH in the video with the thermal image may have been running for a while and/or they may have been running at a low GPM which would increase the heat of water coming out. I have a Flowvis meter (highly recommended, easy to install ) to know how many GPM I'm running.

 

[riny]

they may have been running at a low GPM which would increase the heat of water coming out

Incidentally, there's a reason they recommend a minimum of 45 gpm. Heat transfer occurs between the hot gas and the cold water, through the copper tubing in the heat exchanger. If the water is flowing too slowly then it will get hot, to the point that effective heat transfer can no longer take place. This will cause your AC unit to overheat and shut down. You need a steady supply of cold water to be constantly removing heat.

And remember that greater temperature differences cause more efficient heat transfer. If you slow down the flow rate, you may feel locally hotter water coming out of the return from the FPH, but the overall efficiency will be lower. Unless you're just parked in front of the return, waiting for the warm jet to hit you, this is probably a bad tradeoff.

 

[newpoolj]

Question for the other FPH owners: we noticed that after switching from air cooled to the FPH side of the system, refrigerant moves to the FPH as expected. But when switching back to air cooled the refrigerant seems somewhat stuck and barely moves back to the air cooled side. From what I understand, refrigerant is supposed to go back out of the FPH the same way it came in, then bleed out the top of the 3 way valve and go back into the suction line (maybe this is wrong?) But it seems like this just isn't happening as the charge on the air cooled side stays low and the charge stays high on the water cooled side. Does anyone know for sure how refrigerant is meant to move from the water cooled side back to the air cooled side?

 

[drglanton]

Question for the other FPH owners: we noticed that after switching from air cooled to the FPH side of the system, refrigerant moves to the FPH as expected. But when switching back to air cooled the refrigerant seems stuck and doesn't move back to the air cooled side. From what I understand, refrigerant is supposed to go back out of the FPH the same way it came in, then bleed out the top of the 3 way valve and go back into the suction line (maybe this is wrong?) But it seems like this just isn't happening as the charge on the air cooled side stays low and the charge stays high on the water cooled side. How is refrigerant meant to flow back?

Call hotspot. I had to order a replacement valve.

 

[newpoolj]

Call hotspot. I had to order a replacement valve.

Ah - @drglanton what symptoms were you experiencing on the original valve?

 

[Killian]

I took the plunge and am installing the Hotspot FPH and a new air conditioner at the same time. The AC techs just came to my house yesterday to look at all the equipment and review the installation guides. There seems to be quite a few things that are "field provided". Meaning someone has to go buy them. Having new AC unit moved about 20 feet from pool shed so my water runs shouldn't be too long. I have a shady pool that I estimate is about 15,000 gallons. Live in Michigan and last year had roughly 2 days the pool got to 80. I know I should have a solar cover but I hate them. Hoping this can keep my pool useable during the summer months without a stupid cover. I will update what looks to be a complicated install process once more has happened. I will also uploads some pictures if this site allows it. This thread was helpful and convinced me to give it a try.

Hi Cenovio, I live in SE Michigan, thinking about getting the HotSpot FPH for my 8000 gal pool as my gas heater just broke down, but very nervous about finding an installer. Otherwise setup is pretty good, pool system right next to A/C, with this system we'd have the house thermostat at 68 and the pool thermostat at 90 from June through September. The pool on its own with just a solar cover gets to 82F. The house is 100 years old so not well insulated and A/C runs a lot. Wondering what your experience has been.

 

[DD Urchin]

This looks like a wonderful system for extending our pool season in May, June, and Oct when we still use a lot of AC but the pool is a bit too cold for swimming. Does anyone know if it is possible to install this on a 2-speed HVAC compressor (not variable speed, just two speeds high and low) and does that make it a lot more complex for the HVAC technician? Also my pool equipment room is only 15 ft from the HVAC unit and I wonder if I can just have the condenser lines run to this room, or if I really have to run long water pipes instead to keep the heat exchanger location super close to the HVAC unit for efficiency.

It's funny, on the forums I see that some of the theoretical thinkers tend to dismiss this equipment idea, while just about everyone who actually has one seems to love it.