Just finished my Hotspot energy FPH install, An honest review AMA

[Maverick23]

Wanted to give my thoughts for anyone looking at one of these.

First, shoutout to Devon at Hotspot who answered my many questions. Im sure he is sick of me by now.

My take:

This system while it gives you free heat for the pool is incredibly complicated for a heat pump installation. You basically have to incorporate a second reversing valve into an already pretty busy condenser system. I have a 4 ton HVAC unit which moves 48K BTU plus whatever losses. lets call it 50K BTU to be easy. I am in the south so I get plenty of run time on the AC system.

My biggest take away before purchasing this unit is ask hotspot if anyone has purchased a unit in your area and see if they know the installer who did it. I called 10 HVAC places and nobody would do the work. Everyone told me to call a pool company, or outright declined after looking at the manual. I ended up doing all of the mechanical and system wiring (24VAC and sensors) work myself because I could not find a tech or company in the area who wanted to take the time. I think I realistically spent about 4 days on and off working on plumbing, fitting, brazing, wiring, etc. They claim it's a 4 hour job, maybe if you don't have a heat pump system it's 4 hours and you are highly competent working with HVAC. I have a degree in Mechanical engineering and love working on stuff, but even with that It took a lot of time to complete. this is not considering all the YouTube university time invested to learn the trade. (side note, I will no longer be paying my HVAC company 300 dollars every 6 months to maintenance my system after I learned what they are actually responsible for).

For a heat pump:​

The system involves the addition of a specialized reversing valve for the liquid cooled condenser, a special dual check valve solenoid thing (for heat pump operation), control box, an additional transformer, and an additional liquid receiver to match the capacity of the air and liquid cooling condensers (for me that was an additional 15 feet of 7/8" tubing).​

​

For a standard AC, I think it is just adding the reversing valve, transformer, and additional tubing (easy with the extra space in the condenser).​

To quote my wife "if nobody has it or will do the work, is it actually as good of an idea as it sounds"

She's a smart woman, smarter than me. Was she right? time will tell. The system is working and does indeed heat the pool. It's a trickle compared to a 400K gas unit, but it's enough to maintain heat and it doesn't cost you any additional money once operational. The system was 2300 dollars from Hotspot and I have probably another ~750 dollars in parts and materials (R410A isn't cheap), so call it about 3K all in.

If I had to give it a rating...

1 out of 10 for install difficulty

This thing sucked to install on a heat pump system, plus I have a reversing valve energized to cool which borked their programming, which they are still working on fixing the bug (message me if you want to know more about that)​

5 out of 10 for documentation

I found some inaccuracies in their manual, overall decent but with the complexity this is not a DIY job​

9 out of 10 for operation

It does what it says, it heats the pool with your AC and cools your house very efficiently. I found a workaround for the issue above, but I had to resolve it myself using my working knowledge of electrical systems (only an issue with heat pumps that power the reversing valve for cooling mode, which of course I have)​

​

Overall Score
6 out of 10

• The system is complex
• Absolutely voids your warranty on a HVAC system (convince me im wrong)
• If I sell the house gods speed to anyone who takes over because I doubt anyone will be willing to troubleshoot or maintenance this thing
• Has a fatal flaw in my system arrangement without fix applied
• Trickle heats the pool
• Makes your AC near silent because it stops the fan while in pool heating
• It's cool as heck to show people. Anyone technical will love it
• Controller interface is super simple. Set the temp you want the pool to be and it does the rest.

In retrospect, liquid cooled condensers is more common in commercial HVAC applications. You might have luck contacting a commercial outfit vs residential. A tech that might want some extra work on the side may be interested in taking this job. I would have paid up for the labor, if I was able to find it.

Would I do it again... I don't know, probably because I'm a geek and love cool stuff while saving energy.

 

[Maverick23]

couple of in work photos of the system. I added some additional supports and insulation on parts of the tubing. An absolute rats nest in the HVAC system now.

 

[ajw22]

Thanks for sharing that very candid review and the impressive effort you put into it.

It sounds like a system developed by engineering geeks for other engineering geeks. If you are part of the club you may be able to make it work.

 

[Maverick23]

Thanks for sharing that very candid review and the impressive effort you put into it.

It sounds like a system developed by engineering geeks for other engineering geeks. If you are part of the club you may be able to make it work.

I think you nailed it. Some technical guy was like we are wasting so much energy on this... what if we could...

Honestly that's how I found it in the first place. Google, how to I use my pool water to cool my HVAC... haha.

 

[ajw22]

I think you nailed it. Some technical guy was like we are wasting so much energy on this... what if we could...

It must be a hobby business. I cannot believe they sell many to make any real money.

 

[Maverick23]

It must be a hobby business. I cannot believe they sell many to make any real money.

hard to say how many they sell. They have a video review on thisoldhouse that has been around for a minute so they have been at this for a while.

I thought it incredible that they had not encountered the issue that I was having. Unless they lost some tribal knowledge when someone retired.

The control panel is inside a watertight enclosure but mounted to a 3d printed frame powered by a custom Arduino setup. Definitely not as polished as a Hayward or Jandy level manufacturer.

It is a well thought out system, but retrofitting off the shelf HVAC systems is the conundrum. If I was them I would be more apt to partner with an HVAC manufacturer to just design a series that incorporates the added components. 4 outputs out the back of the HVAC system, 2 go to your house and 2 go to your liquid cooler tied to the pool. One plug to the control box and temperature sensor and you are in business. Im sure there they wouldn't be able to ship direct if that was the setup since you are dealing with refrigerant now.

In any case it was an interesting project, definitely learned a lot.

 

[superdave5599]

I ran across that This Old House clip about this time last year, and have filed it away in the back of my mind. Our AC compressor is actually in the pool area though it seems running the plumbing to the pool pump would be a pain.

Our furnace is still plugging along, though it may be the original to the 1977 house! It is a beautiful aqua color and the home inspector couldn't even find the brand to look up any info. AC seems to be newer, but is still fairly old per inspector. (I recall he commented that if something were to happen to it, the refrigerant it uses isn't available anymore so it would probably need replaced at that time.)

So the home's HVAC is on our longer-term to-do list and I would definitely look at adding this to the system whenever the time comes for replacement.

 

[Maverick23]

I ran across that This Old House clip about this time last year, and have filed it away in the back of my mind. Our AC compressor is actually in the pool area though it seems running the plumbing to the pool pump would be a pain.

Our furnace is still plugging along, though it may be the original to the 1977 house! It is a beautiful aqua color and the home inspector couldn't even find the brand to look up any info. AC seems to be newer, but is still fairly old per inspector. (I recall he commented that if something were to happen to it, the refrigerant it uses isn't available anymore so it would probably need replaced at that time.)

So the home's HVAC is on our longer-term to-do list and I would definitely look at adding this to the system whenever the time comes for replacement.

Probably the easiest time to do it and would be the best time to try to convince someone to do the work. Be aware it will probably void your warranty on the outdoor condenser unit.

 

[VCTC]

Wanted to give my thoughts for anyone looking at one of these.

First, shoutout to Devon at Hotspot who answered my many questions. Im sure he is sick of me by now.

My take:

This system while it gives you free heat for the pool is incredibly complicated for a heat pump installation. You basically have to incorporate a second reversing valve into an already pretty busy condenser system. I have a 4 ton HVAC unit which moves 48K BTU plus whatever losses. lets call it 50K BTU to be easy. I am in the south so I get plenty of run time on the AC system.

My biggest take away before purchasing this unit is ask hotspot if anyone has purchased a unit in your area and see if they know the installer who did it. I called 10 HVAC places and nobody would do the work. Everyone told me to call a pool company, or outright declined after looking at the manual. I ended up doing all of the mechanical and system wiring (24VAC and sensors) work myself because I could not find a tech or company in the area who wanted to take the time. I think I realistically spent about 4 days on and off working on plumbing, fitting, brazing, wiring, etc. They claim it's a 4 hour job, maybe if you don't have a heat pump system it's 4 hours and you are highly competent working with HVAC. I have a degree in Mechanical engineering and love working on stuff, but even with that It took a lot of time to complete. this is not considering all the YouTube university time invested to learn the trade. (side note, I will no longer be paying my HVAC company 300 dollars every 6 months to maintenance my system after I learned what they are actually responsible for).

For a heat pump:​

The system involves the addition of a specialized reversing valve for the liquid cooled condenser, a special dual check valve solenoid thing (for heat pump operation), control box, an additional transformer, and an additional liquid receiver to match the capacity of the air and liquid cooling condensers (for me that was an additional 15 feet of 7/8" tubing).​

​

For a standard AC, I think it is just adding the reversing valve, transformer, and additional tubing (easy with the extra space in the condenser).​

To quote my wife "if nobody has it or will do the work, is it actually as good of an idea as it sounds"

She's a smart woman, smarter than me. Was she right? time will tell. The system is working and does indeed heat the pool. It's a trickle compared to a 400K gas unit, but it's enough to maintain heat and it doesn't cost you any additional money once operational. The system was 2300 dollars from Hotspot and I have probably another ~750 dollars in parts and materials (R410A isn't cheap), so call it about 3K all in.

If I had to give it a rating...

1 out of 10 for install difficulty

This thing sucked to install on a heat pump system, plus I have a reversing valve energized to cool which borked their programming, which they are still working on fixing the bug (message me if you want to know more about that)​

5 out of 10 for documentation

I found some inaccuracies in their manual, overall decent but with the complexity this is not a DIY job​

9 out of 10 for operation

It does what it says, it heats the pool with your AC and cools your house very efficiently. I found a workaround for the issue above, but I had to resolve it myself using my working knowledge of electrical systems (only an issue with heat pumps that power the reversing valve for cooling mode, which of course I have)​

​

Overall Score
6 out of 10

• The system is complex
• Absolutely voids your warranty on a HVAC system (convince me im wrong)
• If I sell the house gods speed to anyone who takes over because I doubt anyone will be willing to troubleshoot or maintenance this thing
• Has a fatal flaw in my system arrangement without fix applied
• Trickle heats the pool
• Makes your AC near silent because it stops the fan while in pool heating
• It's cool as heck to show people. Anyone technical will love it
• Controller interface is super simple. Set the temp you want the pool to be and it does the rest.

In retrospect, liquid cooled condensers is more common in commercial HVAC applications. You might have luck contacting a commercial outfit vs residential. A tech that might want some extra work on the side may be interested in taking this job. I would have paid up for the labor, if I was able to find it.

Would I do it again... I don't know, probably because I'm a geek and love cool stuff while saving energy.

Thank you for this review. We're building now and will be installing a pool. In looking for pool heaters, I came across this one, was intrigued, and sure did like the idea of $'s staying in my bank account!
It sounds like a product with great potential who's time has not yet come for us non-electrical engineering types; we like to knowing that if something breaks down we can't fix, there's someone nearby that can. Also, it sounds like it takes a while to heat the pool, and there's not enough data yet to show long term how it may affect the HVAC or the electric bills. Add in the possibility that using this system could nullify the warranty on a new AC System, we'll pass on this product at this time. But, I'll be curious to see how it advances over the next decade, because it sounds like a winning concept.

 

[nuttyp]

Thanks @Maverick23 – somehow I missed your original post back in April, just noticed through replies the other day. So much of what you wrote resonates fully with me as I, along with many other folks commented in agonizing detail about FPH (Free Pool Heat) 10 years ago across 264 posts on 14 thread pages here. Perhaps you ran across it – eegads it’s a long read! That thread was actually started by @Joshii who kindly wrote a review.

From replies to your more recent posts I got the sense that folks are mostly negative about the FPH system due to several downsides. From my experience with FPH I believe most or all of those noted downsides are indeed true, including your comment that it only “trickle-heats” compared to a gas pool heater – that too seems spot-on. But I suppose we could say that 120K BTU electric pool heaters also “trickle heat”, surely as compared to 500K BTU gas heaters! So I thought I would offer some optimism, and you may already know this from experience. For the 2 ½ years I had the home with the FPH system installed (before I sold and moved), I found it to be a fantastic way to heat the pool – for sure savings from not running another pool heater, but also savings on my sore AC costs as well. Much of the detail is spread throughout that 2014 thread, but suffice to say that FPH heated just as well as my regular 120K BTU electric pool heater does today. From memory (or it’s documented in that other thread) I was saving on the condenser fan not having to run, but also saving on compressor wattage – I think it netted out to save about 20% of the cost of running the standard air cooled condenser unit. I chalked that up to the water cooled condenser being more efficient and the compressor therefore running cooler / less wattage. Since we’re way South in Naples with lots of AC use and with the FPH control wired to run the pump whenever AC is on and pool heat called for – the pool heats all day and night whenever the AC is on. Just for fun, I think it was in December one year we set it to 95 degrees and treated the pool like a spa – for free

One thing noted is that FPH complicates troubleshooting your HVACR system – and nobody to call. The worst thing that happened to me while I owned FPH was one time when my pump failed (stupid Jandy variable speed expensive pump faulting out) and the FPH control logic did not include a water flow (or pressure) switch to turn off FPH in favor of reverting to the air cooled HVAC condenser. My HVAC compressor shut down (on high pressure or overheat), and I caught it as a pool pump problem before any compressor damage occurred. If I do FPH again I’ll include a flow (or adjustable pressure) switch in series with the pid contact outputs that call for pool heat. And I too found an error in their docs, I believe it was that they specified the wrong RIB relay (which I reported to them). If memory serves they had swapped a ‘NO’ relay instead of ‘NC’, or vice versa to control the cooling fan. My FPH PID controller also failed after a year, but I replaced it with a $10-$20 temperature controller from ebay/amazon, similar to this. And I remote mounted it in a std wall box inside the house. Even the home I’m in today I use one of those cheap controllers to control the pool heat.

Did I say “if I do FPH again”? Although my background is in electronics engineering, a few weeks ago I stumbled into the that research and training monster you referenced called the HVACR field. I was always interested and understood the basics (always considering DIY for anything really) but started down the HVACR road because my ancient pool heater leaked it’s R22 refrigerant and it quit. So I sought a cheaper alternative than spending $5K for a new heater. I have some time before fall/winter and I ran across a guy with several Built Right heater units sitting in his cow field and he sold me one cheap, at my risk. Fast forward 3 weeks and soon I will have all the necessary tools for HVACR (lots of ‘em, right? to do it right, safely, and legally) along with an EPA 608 Type II certification. And I already have my 115K Built Right heater up and working, for the cost of all the tools

But guess where it leads me? To that old pool heater and it’s heat exchanger. And now that I know HVACR (and can now fix my own AC as needed), why don’t I use that old heat exchanger and new knowledge to build my own FPH? Wife says, are you sure you want to take all that on? What’s the worst that could happen, forget to flow nitrogen while brazing in the refrigerant valve and leave pipe embers and residues that ruin my home’s AC compressor? I suppose I could screw it up other ways! But I have a couple window AC units for emergencies – LOL. And my AC is not a heat pump so less complicated than yours, for sure.

If that’s not enough to tackle, now I’m wondering if I can modify the Built Right heater with refrigerant flow reversal valve(s) to cool the pool. Aquarite sells a pool heater model that does that, how hard could it be? Well, just a thought – first things first. But we in the way South are having issues with 90 degree-plus pool water in summer. “What a problem to have”.

Hope you enjoy your FPH – I think you will !! It just isn’t for everyone.