Hotspot FPH AC heat reclamation pool heater - a review!

cenovio

New member
Apr 1, 2016
3
Belmont/Michigan
Here is a short update on the FPH. I would say it makes about a 5 degree difference for me on average. Which for me has been great. There is a huge different between a 72 degree pool and a 77 degree pool. In Michigan the past week it has been cool at night and high 70s during the day. Without the pool heater my pool was around 72-73 in these conditions. With the pool heater it is around 77-78. During the really warm months with AC running a bunch and outside heat the pool was an 88 degree spa. So for making the pool nicer during swimming months it works great. Basically no chance of this thing really extending my season at all. Which is fine for me. Spent enough money on stuff that closing up the pool now doesn't bother me. But had lots of fun in the hot July months with a super toasty warm pool when last year even in July it would barely touch 80.
 

OneLoveAmaru

Member
Apr 17, 2017
10
Tampa, FL
I just ordered mine, i'm in Tampa, FL, where my A/C runs pretty much 24/7, 365 days a year. Paid $1945 for the FPH from HotSpot for the 2.5 to 3.5 ton unit. I've got a quote of $800 to $1,000 to install. My A/C unit is less than 10ft from my pool pump, so it should be on the low end of that.

I'll post back once it's installed and have some real world results.
 

sghgirl

New member
May 3, 2017
2
Teaneck, NJ
I have been looking at this product for the better part of two years and I'm very happy to say we have finally got one installed! I am very happy with this product and am equally happy to supply one of the first reviews of it. I know one of my own biggest uncertainties was the dearth of reviews out there: Will my pool get too hot? Will it work at all? The heating and cooling needs are not matched. The summer is hot already, etc. With no reviews, we basically had to just take the plunge. I hope this sheds some light onto the product, how it works, and will help someone else with their pool heating decision.

The Hotspot FPH heat reclamation pool heater, website here, is a device that connects to your central AC unit and redirects the waste heat from your house back into your pool. So, instead of the giant fan on the outdoor AC unit spitting the waste heat from your house into the sky, the Hotspot FPH unit instead puts the heat into your pool water.

It does this by running the hot AC refrigerant coil through a small canister through which your pool filter connects and sends the water through. Essentially, it heats the flowing water like a tea kettle using the heat from the AC coil. I will update this post with pictures in the coming days.

Here is an album with some pictures of the install: Hotspot FPH build - Album on Imgur

The whole concept of this product really appealed to us. In fact, we went searching for this solution over two years ago before we knew the product even existed. I stumbled onto it quite accidentally when watching an episode of Ask This Old House which featured this product. The appeal is just how complimentary the two systems are -- in the summer, you want to cool your house AND heat your pool.

One more thing to note before jumping into the review is that I live in the northeast, where the summers are warm and the spring and fall are cool. I am not looking to extend our swimming season with a pool heater. I know several households with more conventional propane or heat pump pool heaters who don't extend their season either, since in the northeast, it is astronomically expensive to do so, even for an additional month on either end of the Summer.

Rather, we are looking to maintain a warm and consistent pool temperature during the swimming months from late June to early September. Our pool will naturally get to 80 degrees from ambient heat and sunlight alone, assuming there is a nice stretch of no rain. That's not bad, but it's not ideal either. We're looking to keep the pool at or above 84 degrees consistently, rain or shine, during the summer swimming months.

The Hotspot FPH pool heater will do just this. Unfortunately, we just got this installed at the tail end of this swimming season but I can report my results as of now. When installed two days ago, my pool temperature was 78 degrees. The water coming from the return after being heated was 2.5 degrees warmer than the regular pool water -- 80.5 degrees. Since the pump can filter all the water in the pool once every 8 hours, we can ideally heat the pool by 2.5 degrees every 8 hours. Obviously, this will depend on AC use as well.

As of now, my pool is at 80 degrees and rising. This is pleasantly surprising even to me, considering how cold the nights have been around here lately. I'm hoping we can get it above the 84 degree mark by the end of September, but I don't think we'll hit it this late into the season.

The concept of this heater is a bit different than conventional heaters. A conventional heater is absolutely massive, capable of heating a pool 10 degrees or more in a few hours. A typical heat pump pool heater can supply over 100,000BTUs/hr of heat to the pool. My 3 ton home AC when paired with the Hotspot unit can supply 36,000BTUs/hr of heat to the pool. However, where a conventional pool heater is only meant to be run a few hours at a time, intermittently, home ACs are designed to run more frequently and more consistently. This means that the Hotspot FPH heater will heat the pool more slowly and respond more slowly to shocks in pool temperature. But, since it is run frequently, it is ideally suited to maintaining a set pool temperature.

If, like us, this is what you're looking for in heating a pool, then this unit will be perfect for you as well.

To get into the nuts and bolts of the install, the unit consists of two parts: a blue canister that sits on the ground and has 4 connections, 1.5" water in, 1.5" water out, and two refrigerant lines, one hot (input) one cold (output). The other part is the controller unit that gets mounted to your house.

The water lines divert through the pool heater in the typical way: right after the filter and before returning to the pool. If you're really handy, you can probably do this yourself. I hired a plumber.

The refrigerant lines get split and connected to a 3-way valve, to either be cooled by the normal fan unit, or by your pool water. The system is fail-safe, in that if power is cut to the FPH controller unit, the AC system defaults to fan cooling. I had *many* questions about the operation, safety, and handling of edge conditions with regard to this rather complex setup that I won't go into here, but if you have any questions I would be happy to answer them. The bottom line, however, is that the Hotspot engineers are pretty smart guys, and have thought about all these cases already and developed a nice, safe, reliable product that I'm confident is not going to break my pool or my AC system.

In fact, I have no doubt my AC system is going to operate more efficiently now that it is water cooled. It is wild to see my house AC on without the fan on. The outdoor unit is MUCH quieter! And the refrigerant lines leaving the water cooling canister are distinctly cooler than when they are fan cooled.

In fact, my HVAC guy had his equipment set up reading the pressure gauges of the refrigerant lines between air cooled and water cooled modes. When air cooled, the pressure was 300psi. When water cooled, the pressure was 100psi. The translation of this that I got from my HVAC guy was that the compressor was working much less hard when the refrigerant is water cooled than when it is fan cooled, meaning it uses less energy and will extend the life of the compressor. Obviously, the fan isn't going either which saves somewhere around 300-500 watts of power as well from what I can tell.

The controller unit takes in electrical connections, 120VAC home current to power itself, and takes in 240VAC lines for your pool pump, so that it can turn on and off your pool pump regardless of the pool pump's timer settings. I know more than I strictly need to now about how that all operates and if, like me, you have questions regarding this I will be happy to answer them.

The controller unit also takes in low voltage wires from the compressor to control fan usage and when operating in water vs air cooled modes. With the controller unit off, the system defaults to fan cooled mode. Fail safe by design.

The installation costs were high but not surprising, considering I live in the northeast.
The FPH unit cost $1800.
Plumbing cost $500, $250 labor, $250 materials. I had about 60' of additional PVC runs to make.
Electrical was $500, $300 labor, $200 materials.
HVAC was $1200, $800 labor, $400 materials.

Total cost was $4,000.

I was eager to share with you my experience with the install and operation of this pool heater, as there is a lot of interest out there, a lot of theories of whether it will work, whether it will heat the pool at all, or overheat it, etc, and virtually no reviews of an actual install out there. I hope this helps some of you who may be thinking about installing such a system for your own pool. I would not hesitate to do so again. Every time I see an AC unit spitting perfectly good warm air into the sky I think what a shame, it could be put to such good use.
Hi! We have just bought this unit-we live in Bergen county in New Jersey. The only problem is that we can't find an hvac company to install it!! Do you live in my area and can tell me which company installed yours? Thanks!
 

OneLoveAmaru

Member
Apr 17, 2017
10
Tampa, FL
I just ordered mine, i'm in Tampa, FL, where my A/C runs pretty much 24/7, 365 days a year. Paid $1945 for the FPH from HotSpot for the 2.5 to 3.5 ton unit. I've got a quote of $800 to $1,000 to install. My A/C unit is less than 10ft from my pool pump, so it should be on the low end of that.

I'll post back once it's installed and have some real world results.
I also can't seem to find anyone in Tampa, FL to install mine either. The one company that HotSpot recommended has flaked on me twice and now has told me I need to find another company to install it. :(

Any near Tampa that can offer any advice?
 

AlanM

New member
May 5, 2017
1
Jacksonville FL
OneLoveAmaru, I'm really curious how this goes for you. I'm up in Jax. As far as installers I had similar trouble on my initial search. Asked around at all the big name local AC guys and it was a no way no how... No one wanted to touch it. I've got a buddy that does AC stuff on the side and he's all in. I'm just trying to roll my pennies up at this point as been a hard year. I'll check with him if he knows anyone down that way but my guess would be similar luck and gonna need to find the little guys to do it.. Good luck I'm looking forward to hearing how it goes and will let you know if he has any contacts.
 

OneLoveAmaru

Member
Apr 17, 2017
10
Tampa, FL
OneLoveAmaru, I'm really curious how this goes for you. I'm up in Jax. As far as installers I had similar trouble on my initial search. Asked around at all the big name local AC guys and it was a no way no how... No one wanted to touch it. I've got a buddy that does AC stuff on the side and he's all in. I'm just trying to roll my pennies up at this point as been a hard year. I'll check with him if he knows anyone down that way but my guess would be similar luck and gonna need to find the little guys to do it.. Good luck I'm looking forward to hearing how it goes and will let you know if he has any contacts.

I appreciate that and I will definitely update this thread once I get this thing installed and start seeing some results.
 

Joshii

Well-known member
Jul 15, 2013
232
Yes, please do! The hardest step of the process is finding the HVAC contractor. When you find one, it will be helpful to know how you found them.
 

CaptainCannonball

Silver Supporter
May 18, 2016
272
Woodland, Ca
I detest waste, and when I saw an ac compressor spewing hot air next to my pool, I wanted so badly to be efficient and reclaim that heat. I hesitate to post this because I don't want to hurt anyone's feelings, but logically the btu's just don't add up.

Let's make some "best case" assumptions to start out with. We will start with a larger than average 5 ton system that could produce 5x12000 or 60,000 btus/hr. That is assuming a 100% heat transfer rate and let's also assume a 100% duty cycle of the AC compressor.

Now lets work work back to reality, compressors typically take up to 5 minutes of a duty cycle to reach their optimum heat transfer. HVAC systems will run non-stop but if properly maintained and sized they should run 30-50% of the time. If the system is running 100% of the time, then the house needs better insulation, the unit is undersized or it is underperforming.

If your HVAC is functioning as designed, one could hope to "harvest" 20-30,000 btus/hr or enough to heat a relatively small pool (10k gallons) one degree every four hours. Don't forget that your pool pump needs to be running that whole time, so to heat that modest sized pool two degrees your pump needs to run for 8 hours, 3 degrees 12 hours and so on.

There appears to be a fair amount of anecdotal evidence about the real world effectiveness, my speculation about the 2.5 degree rise is it happened after the compressor reached optimum efficiency and certainly not during times between on cycles. Venting your house of cold air in order to use your air conditioning to heat a pool is plain bonkers very inefficient. :)

When I considered this for my pool, it would take 8 hours of air conditioner usage to raise our pool temperature one degree. A heat pump would have done the same in about an hour and its power consumption would easily be offset by reducing pump time. Do the research, calculate the btus and explore your options. Unfortunately for this admittedly cool idea and awesome implementation, the juice isn't worth the squeeze.
 

magsaudi

New member
May 8, 2017
1
Fl
You're right. This is not for everyone. I was lucky. Small pool, Ac on same side as pump. I did have to get a new VS pump, as my hayward VS, not compatible. Just turned on new system tonight...ran system for 45 mins. Water rose from 77 degrees to 81 degrees during our test. AC much more efficient. We live north of Tampa FL. I can't share installer with you. He can blog if he is interested in doing another. I hope he will.
 

wayner

LifeTime Supporter
May 31, 2012
483
Toronto, ON
There appears to be a fair amount of anecdotal evidence about the real world effectiveness, my speculation about the 2.5 degree rise is it happened after the compressor reached optimum efficiency and certainly not during times between on cycles. Venting your house of cold air in order to use your air conditioning to heat a pool is plain bonkers very inefficient. :)
I can understand why the system may not be efficient, but why is it bonkers for those of us that have Natural Gas heaters can offset some of the natural gas. Are you saying that the system simply does not work and does not add heat to the pool at all?

Let's assume the cost is $4000 but that offsets $400 per year in natural gas and that the system has a 15 year lifespan. That is a 6.5% IRR and that is with after tax dollars. Perhaps not great but not terrible if you are in a high tax bracket and it is reducing your carbon footprint.

To fully do this calculation you would need to know how much natural gas you would save to know if my $400 guess was anywhere near accurate. Anyone have an idea on that?
 

CaptainCannonball

Silver Supporter
May 18, 2016
272
Woodland, Ca
Bonkers was in reference to the poster that was talking about opening their windows to heat the house up in order to get more btus into their pool.

Spend your money how you want to, I'm saying there are more effective and efficient methods to heating your pool.
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
To measure the effectiveness of any pool heating device you have to measure the heat gain over a period of time. For instance, my heat pump adds 1 degree to my pool every three hours and it also adds 3 degrees over 12 hours. This can also be validated by calculating the btu output vs the amount of water in the pool. All the math works.

My solar panels can add 5-8 degrees to my pool from sun up to sun down depending on how sunny/cloudy it is. It is harder to calculate/estimate btu output of solar panels because you can't control or measure the solar gain.

I think the 4 degree temp rise might have been the input temp vs the output temp, ie entering water temp was 74 and exiting water temp was 78, not that it heated the pool water 4 degrees in 45 minutes.

I would think Hotspot would be able to estimate or calculate the btu output based on how many tons the unit is. I haven't turned my AC on yet this year though and I've been heating my pool since late February with solar and since early March with the pool heat pump and we've been swimming since March 13th.
 

wayner

LifeTime Supporter
May 31, 2012
483
Toronto, ON
Spend your money how you want to, I'm saying there are more effective and efficient methods to heating your pool.
And what are those? Solar? Heat pump? Electrical? Oil? Here in Canada we generally use Natural Gas heaters for our pools. I have put in a solar system to supplement my natural gas as we like to keep the pool at 85F during the prime swimming season of early June to late August. But keeping a pool at that temperature in this climate will cost you a couple of thou per year.
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
A heat pump would likely be the most efficient way to maintain water temp at 85 during the summer in Canada. Along with a solar cover to keep the heat in overnight.
 

CaptainCannonball

Silver Supporter
May 18, 2016
272
Woodland, Ca
I believe it is good to have a robust conversation about technologies like this. I also believe that empirical data that is backed up by scientific feasibility is important to others making a sizable financial outlay. If one boils it down to the cost of btus while factoring in extended pump run times it is difficult at best to justify the costs involved.

Im not arguing that this device puts heat into pools, because quite frankly it does. I simply am looking at how much it does. A 137,000 btu/hr heat pump would destroy this in performance for half the cost. I've said my peace, I have no vested interest. My analysis is simply a way that I can help contribute to this community.

Sincerely,
CC
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,866
Sebring, Florida
I am in complete agreement with CaptainCannonball.

I always look at how quickly I will recover my financial outlay in energy saved. The answer is most always, "never"

I admire the ingenuity involved in this system. Well thought out by some dedicated, sharp folks but I don't think the economics work.
 

wayner

LifeTime Supporter
May 31, 2012
483
Toronto, ON
For some reason you don't seem to see many heat pumps here - pretty much all you see is NG. The capital cost for a heat pump appears to be about 2X what heat pumps are. When I go to a Canadian online pool retailer for my 18x36 pool they recommend a 250,000 BTU heater which are about C$2000. For heat pumps they recommend 125,000 which are about C$3800. Any idea what the average operating cost difference would be between the two? Food for thought when I have to replace my ten year old natural gas heater. Any downside to the heat pump, like taking longer to heat up?
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
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Aug 10, 2012
25,412
FL panhandle
The biggest heat pump I've seen is 140k btu and they do cost about $4k. Yes, they will take longer to heat up and they don't work very efficiently below 50° or so. But, who swims when it is below 70? Or better yet 80? Heat pumps are more efficient by a factor of 4-5x in terms of converting energy into heat over gas.

More here, How Much Does it Cost to Run My Pool Heater? - INYOPools.com
 

The dog

Well-known member
Apr 17, 2017
147
sacramento CA
This is great.

First real use of Cogen I have seen, at a residential level, that makes sense.

If you are really slick go get a 7-10 ton heat pump hvac. You can run both your house and heat your pool at the same time. You'll need to get a heat exchanger (that's what that blue barrel is), and some fancy controls and valves. If you're even slicker you could run it all through your easy touch.


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