Hotspot FPH AC heat reclamation pool heater - a review!

Fossil_bil

Member
Oct 5, 2017
6
Riverview, FL
@pooldv, I asked my installation company that very same question. They stated they don't directly install their pool equipment, they subcontract that work to an electrician/plumbers/gas company. They don't want to add another layer of complexity by bringing in a new (innovative) product. Remember that not everyone (at least in FL is what they said) orders/installs heaters (gas/electric/solar). So adding another product that would probably not sell in mass quantities would not add a lot of value to their bottom line. The complexity would also include covering warranty for an expensive part of the home that is probably not new and not installed by them (A/C), a modification to the air conditioner (ie. if there is an issue with the A/C they are now in the hook). Not to add that people are creatures of habit, often unwilling to try or adopt new things.
 

Fossil_bil

Member
Oct 5, 2017
6
Riverview, FL
I just spoke with a large A/C, electrical, plumbing, gas contractor in central Florida and they are sending one of their technicians to review the equipment, installation, etc on Monday. The company representative on the phone stated they have experience installing similar equipment for water heater, but have not installed one for pools before. They are interested since it is similar technology. Will update once I get their take on it.
 

Joshii

Well-known member
Jul 15, 2013
225
That's really fantastic! This technology has been around for ages and is very commonly used in commercial spaces. Like grocery stores, industrial freezers, etc. Glad to see a company stepping up.
 

OneLoveAmaru

Member
Apr 17, 2017
10
Tampa, FL
I just spoke with a large A/C, electrical, plumbing, gas contractor in central Florida and they are sending one of their technicians to review the equipment, installation, etc on Monday. The company representative on the phone stated they have experience installing similar equipment for water heater, but have not installed one for pools before. They are interested since it is similar technology. Will update once I get their take on it.
Did you manage to find someone? I might need someone to fix my system, it's still acting weird, even after the solenoid valve change.
 

danielbheyl

New member
Dec 30, 2017
1
Austin
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.

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 am confused why the system needs to be so complex. Why not just part 1 (blue heat exchanger)? Why is there a need for the second part which adds complexity, failure points, and cost to the system. I would prefer to use just the heat exchanger to pre-cool the refrigerator and let the ac system work normally without shutting part of it down. I must be missing something here. What is wrong with this proposal:

1. Connect blue heat exchanger in front of and inline with the outdoor condensor unit.
2. Connect plumbing to pool.
3. Install jandy valve with actuator to divert water into or bypass blue heat exchanger.
4. Tell Jandy (or another controller) to close the valve when the temperature is satisfied.
5. Done. Do not install 3-way valve on refrigerant line. Do not install another controller. Do not interrupt normal condenser fan operation.

Wouldn't this basically accomplish the same thing? When heat is needed to the pool, water goes through the system heating the pool and pre-cooling the refrigerant before it gets to the outdoor unit where things work as normal (the condenser is the second method of cooling)... when the pool is satisfied, the water stops flowing and the cooling is done only with the outdoor condenser fan as it always did before installing the heat exchanger.

Blue Heat Exchanger: $495 (Aliexpress.com : Buy Free shipping ! 29.0KW tube heat exchanger for swimming pool best selling products from Reliable exchange application suppliers on Refrigeration Equipment High Quality)

Install: Much less because it is much less complicated.

Total: $1,500 maybe?

I understand that because the AC condenser fan is also cooling, I am losing some heat to the atmosphere but in turn using both is putting less stress on my compressor.

The only other downside I could see is that possibly the stagnant water inside the blue heat exchanger warms up to unacceptable temperatures (up to 225?) without water flowing through but that does not seem likely at all.

Thoughts?

(Approved by Jim R. 1/10/2018...)
 

Joshii

Well-known member
Jul 15, 2013
225
That's actually a really good idea! It does simplify things, sure. I don't know. But I will say it is very nice being outside in the summer and not having to hear the AC fan! And that saves like 300w of electricity, too. It's a big fan.
 

catiare

Member
Jan 15, 2017
8
Miami, FL
That's actually a really good idea! It does simplify things, sure. I don't know. But I will say it is very nice being outside in the summer and not having to hear the AC fan! And that saves like 300w of electricity, too. It's a big fan.
Perhaps, the on/off cycle of the compressor will be less frequent due to the fact that the refrigerant has been cooled enough by water.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,856
Tucson, AZ
I’m not an HVAC expert but I think the problem with Post #125 is that if you pre-cool the refrigerant too much, then you could wind up converting the refrigerant from a gas to a liquid INSIDE the compressor pump. Normally the compressor takes warmed gas from the evaporative coils and compresses it into hot gas before sending it into the condenser. Once inside the condenser coils, the fan cools the high pressure refrigerant into a liquid and that liquid is then transferred back to the evaporator through a control/metering valve. The trick in proper operation is to make sure the refrigerant gas is at the correct pressure and temperature at each point in the system. If you pre-cool the gas too much before it enters the compressor, it will liquify too soon and then damage the compressor pump as they are designed to operate with gases, not liquids. This is also the reason why it’s important not to accidentally introduce any water vapor in the refrigerant line when recharging the system or else you can cause serious damage to the compressor. Most AC systems will have a zeolite drying filter inline to absorb any stray gases.

So in order to not damage your AC, the HotSpot system needs to monitor and adjust the refrigerant flow to ensure proper operation.
 

AusMacca

New member
Mar 23, 2018
3
Perth, Australia
I am confused why the system needs to be so complex. Why not just part 1 (blue heat exchanger)? Why is there a need for the second part which adds complexity, failure points, and cost to the system. I would prefer to use just the heat exchanger to pre-cool the refrigerator and let the ac system work normally without shutting part of it down. I must be missing something here. What is wrong with this proposal:

1. Connect blue heat exchanger in front of and inline with the outdoor condensor unit.
2. Connect plumbing to pool.
3. Install jandy valve with actuator to divert water into or bypass blue heat exchanger.
4. Tell Jandy (or another controller) to close the valve when the temperature is satisfied.
5. Done. Do not install 3-way valve on refrigerant line. Do not install another controller. Do not interrupt normal condenser fan operation.

Wouldn't this basically accomplish the same thing? When heat is needed to the pool, water goes through the system heating the pool and pre-cooling the refrigerant before it gets to the outdoor unit where things work as normal (the condenser is the second method of cooling)... when the pool is satisfied, the water stops flowing and the cooling is done only with the outdoor condenser fan as it always did before installing the heat exchanger.

Blue Heat Exchanger: $495 (Aliexpress.com : Buy Free shipping ! 29.0KW tube heat exchanger for swimming pool best selling products from Reliable exchange application suppliers on Refrigeration Equipment High Quality)

Install: Much less because it is much less complicated.

Total: $1,500 maybe?

I understand that because the AC condenser fan is also cooling, I am losing some heat to the atmosphere but in turn using both is putting less stress on my compressor.

The only other downside I could see is that possibly the stagnant water inside the blue heat exchanger warms up to unacceptable temperatures (up to 225?) without water flowing through but that does not seem likely at all.

Thoughts?

(Approved by Jim R. 1/10/2018...)

I have been thinking about this all along whilst going through the thread.

Why cant this be done???????
 

Joshii

Well-known member
Jul 15, 2013
225
I have been thinking about this all along whilst going through the thread.

Why cant this be done???????
I will say a couple things against this plan.

(1) It still requires a controller, just not one controlling the refrigerant
(2) It doesn't stop the fan from operating, so no cost savings there (nor sound savings which is actually more important to me ... makes my AC very quiet)
(3) Like you point out, it is not putting all heat into the pool. And considering the fan is enough to cool the entire house all by itself, I would say it would be stealing HALF the heat from the pool. That is a nontrivial amount!
(4) The Hotspot guys actually know what they're doing with this stuff. See the other post recently by a poor homeowner who chose a HVAC guy who thought he knew better than them ("no need for THAT part. Har Har") and blew up their system. To be honest, this idea sounds very much like that line of thinking. Reasonable on the surface. But in reality, what do I know!
 

AusMacca

New member
Mar 23, 2018
3
Perth, Australia
I will say a couple things against this plan.

(1) It still requires a controller, just not one controlling the refrigerant
(2) It doesn't stop the fan from operating, so no cost savings there (nor sound savings which is actually more important to me ... makes my AC very quiet)
(3) Like you point out, it is not putting all heat into the pool. And considering the fan is enough to cool the entire house all by itself, I would say it would be stealing HALF the heat from the pool. That is a nontrivial amount!
(4) The Hotspot guys actually know what they're doing with this stuff. See the other post recently by a poor homeowner who chose a HVAC guy who thought he knew better than them ("no need for THAT part. Har Har") and blew up their system. To be honest, this idea sounds very much like that line of thinking. Reasonable on the surface. But in reality, what do I know!

I don't see any of the above a compelling reason why not to do it this way.
I think the guys that make it need to comment on if there is a technical reason why it cant be done.

To answer the points above.
1. No controller required on the refrigerant side. Controller on the pool side is simple and can be easily done by owner.
2. Having the both the water and fan cooling would only make the A/C more efficient. Yes some heat is lost to the air, but less electricity is required to keep the house cool. A fan uses only a small amount of power, less than 10% of the power used by the compressor.
3. See above
4. I'm not saying that the hotspot guys don't know what they are doing, just asking if this "simpler" application could work.

I would imagine that if when buying a new A/C, simply installing "in-line" extra pipe in the form of one of these units, would be more likely to keep the unit under warranty; rather than the more complicated modification that shuts down parts of the system. I think Warranty would be void straight away.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,856
Tucson, AZ
I posted this in an earlier post but I will reiterate again - heat pumps work on a very specific set of temperature and pressure operating points to maximize heat transfer efficiency. One very dangerous thing that could happen if you put the water cooling unit in front of the AC compressor is that you could potentially pre-cool the refrigerant too much that is coming from the evaporative exchanger and the refrigerant could accidentally liquify inside the compressor. If that happens, you can blow up the compressor because they are designed to compress gases, not liquids. The refrigerant gets compressed and cooled in the condenser coils by the fan and that is where you want the refrigerant gas to potentially liquify where it will do no damage.

I also suspect the HotSpot guys setup their system so the compressor is pushing the high pressure gas either thru the air heat exchanger OR through the pool water heat exchanger but NEVER both. This way they can avoid possible damage.

I would agree that, no matter the arrangement, most AC manufacturers would call a warranty void by the end user putting any modification on the system. That would just be standard liability practice.
 

AusMacca

New member
Mar 23, 2018
3
Perth, Australia
I posted this in an earlier post but I will reiterate again - heat pumps work on a very specific set of temperature and pressure operating points to maximize heat transfer efficiency. One very dangerous thing that could happen if you put the water cooling unit in front of the AC compressor is that you could potentially pre-cool the refrigerant too much that is coming from the evaporative exchanger and the refrigerant could accidentally liquify inside the compressor. If that happens, you can blow up the compressor because they are designed to compress gases, not liquids. The refrigerant gets compressed and cooled in the condenser coils by the fan and that is where you want the refrigerant gas to potentially liquify where it will do no damage.

I also suspect the HotSpot guys setup their system so the compressor is pushing the high pressure gas either thru the air heat exchanger OR through the pool water heat exchanger but NEVER both. This way they can avoid possible damage.

I would agree that, no matter the arrangement, most AC manufacturers would call a warranty void by the end user putting any modification on the system. That would just be standard liability practice.
Ludicrous. Are you trying to say that 80 degree F pool water is going to turn the refrigerant to a point that is so cold that it is going to turn into a liquid? These units (unmodified) can operate at temperatures well below freezing.
 

catiare

Member
Jan 15, 2017
8
Miami, FL
Knowingly losing half your heat to the air when the intended use of the system is to put that heat into the pool is not a compelling reason?
I don’t understand how the system would lose heat to the air. The heat exchanger would be before the compressor not after.

The only inefficiency I see is the compressor always working in lieu of a simpler setup.

Also, since the fan turns on demand, I would assume the fan would cycle less frequent since the coolant doesn’t need it.

My apologies in advance I know very little about HVAC functionality.
 

saver

New member
Jun 9, 2018
3
SW Florida
What is wrong with this proposal:

1. Connect blue heat exchanger in front of and inline with the outdoor condensor unit.
2. Connect plumbing to pool.
3. Install jandy valve with actuator to divert water into or bypass blue heat exchanger.
4. Tell Jandy (or another controller) to close the valve when the temperature is satisfied.
5. Done. Do not install 3-way valve on refrigerant line. Do not install another controller. Do not interrupt normal condenser fan operation.
I would even simplify this by eliminating steps 3+4 (and 5 is not a step actually). Just let the water flow through the heat exchanger, and let natural dissipation take care of cooling off the pool, as far as necessary....

You would actually get something like this:
https://www.homedepot.com/p/ZeroEnergy-Heat-Recovery-Water-Heater-System-Zero-Energy-ZE-TSHRU/203715807

Now this is used for a water heater, and not a pool, but it basically is just a heat exchanger without any moving parts. And this doesn't seem to damage the AC unit, although, the "cooling capacity" of a water heater (100 gallons) is much lower than that of an entire pool (10.000 gallons).

I was thinking about putting something like this in my AC hot line: https://packless.com/products/condenser-wshp-coils/capacity/1 , the only question would be: would this survive if no water would be circulating?
 

sccm_sysadmin

Well-known member
Apr 25, 2017
215
Greensboro, NC
It frustrates me to no end that I pay money to remove heat from my house and dump it into the atmosphere...and I also pay money to remove heat from the atmosphere and add it to my pool.

But at the prices I see quoted in this thread, the fact that my pool does get decently warm in the summer by itself, plus the fact that my pool equipment is a good 80-90ft from my HVAC equipment (and I'd have to pay to have that trenched), it just isn't worth it to go this route for me. Oh well. I'm glad it seems to be working well for those who are using it.
 

orthopod

Gold Supporter
Jan 12, 2008
113
Braselton, Ga
Thanks for the writeup, I am considering adding one to my pool. We will have a gas heater for the spa and when the weather drops too much but this FPH hotspot heater looks very interesting to me.

I live in north atlanta, and we run the AC all the time. I think this would work great in april/may and september and october, and because our pool is very shaded. I dont like very cold pools!

Are you still happy with the system? How about a several year update!!

Do you have the ability to set it to a water temp setpoint so it doesnt keep heating the pool?

Would you install it again?

I may just do a Jandy HEatpump/Chiller Combo.

Any idea if its resulted in any cost savings for you in you HVAC bill? Looks like "free heat"


thanks!
 

kmheid

New member
May 21, 2016
2
Aurora
I have had mine installed for 2 years now. It works well, but not as well as I had hoped. I live in Colorado, so our season is short. I installed a gas heater to get it up to temp in the Spring, and keep the temp up in the Fall. Once I get the temperature up to where I want it, the heat exchangers do a good job of maintaining it if I keep the pool covered.
I don't have to run the gas heater in summer, but I have a large house with 2 A/C units; both connected to the FPH (2 heat exchangers). I have a variable speed pump, and tried to connect it to home automation to only run the FPH when the pump was on, but I never got that to work reliably and had a few incidents where the FPH was on and the pump wasn't, causing the compressor to go into emergency shutdown (not good). Now, I just run the pump 24/7 with the FPH always engaged, and that works much better. In July and part of August, I can uncover the pool and it stays in the 80's (unless we get a cold spell).
It's more complex than most HVAC techs want to deal with. I got lucky and found someone that normally does commercial stuff, so this system was right up his alley. I think a good installer is important. Still, I sometimes have problems with our HVAC that I don't think I would have if we didn't have the extra complexity of the FPH.
I love efficiency and the idea of dumping heat from the house into the pool, but I'm not sure if I would do it again. Since I ended up having to buy a gas heater anyway, I don't know if I will ever recoup the cost of the system. Overall I am happy with it and think it is a good product, but it will probably not end up saving me money. Mine is probably the marginal case, but there are others where it totally makes sense. The product itself is good.
 

Fossil_bil

Member
Oct 5, 2017
6
Riverview, FL
Thanks for the writeup, I am considering adding one to my pool. We will have a gas heater for the spa and when the weather drops too much but this FPH hotspot heater looks very interesting to me.

I live in north atlanta, and we run the AC all the time. I think this would work great in april/may and september and october, and because our pool is very shaded. I dont like very cold pools!

Are you still happy with the system? How about a several year update!!

Do you have the ability to set it to a water temp setpoint so it doesnt keep heating the pool?

Would you install it again?

I may just do a Jandy HEatpump/Chiller Combo.

Any idea if its resulted in any cost savings for you in you HVAC bill? Looks like "free heat"


thanks!
I live in Tampa, FL and had the hotspot for about 6 months. We did have compressor going bad during that time, so the FPH probably was not working at optimal efficiency. The compressor was not maintaining constant pressure.

After we had the compressor replaced....UNDER WARRANTY (House is 3 years old, just had to pay for labor). The FPH dumps a ton of heat into the pool throughout the day.

Yes there are temperature set points, which can be modified up or down.

Yes I would install it again, but with caution:
1. You need an expert installer, possibly commercial experience. One that understands that you will call them a few times after installation for questions, assistance, issues, etc. It tool a few questions back and forth between HotSpot, me, and the installer to get it dialed in.

2. You need to monitor the hotspot and the installation to ensure its dialed in and working properly. After the compressor was replaced, Hotspot is on autopilot.

3. Collect data before you install and after. Every location and environment is different. for example, the orientation of your pool (ie north, east, west, south), amount of shade, screen or not, location (ie. FL versus Colorado cannot be compared) etc.. So everyone's results will obviously vary. For me in Tampa FL, I wanted to not only make my water comforatable during the swimming season (ie +4-5 degrees), but also wanted to extend swimming season to almost year round. I think now that its dialed in I will definitely almost get year round swimming.

4. I have heavy Hayward automation. So we added a independent pump for the HOTSPOT. I've seen some, that just have their primary pump run 24/7 on low speed, but I don't like that idea for various reasons (ie if you have a heated spa...the temp will exceed safety margin for cooling Freon, running the pump 24/7, etc). I didn't like the way it was plumed to the same outflow pipping to the pool, bypassing the filter and working against my primary pump when on. So I took a Saturday installed a separate filter for the FPH pool pump we installed and also isolated the outflow return to the ones on the floor. The extra filter was great idea, as I get extra filtration while the FPH pool pump is running This great, the primary pump does not have another pump creating head pressure, I visually see the water ripples from the bottom pipe...telling me the FPH is on, it also concentrates the heat better (higher temp on the outflow the better, the other way diluted the temperature), and now my automation/spa has no issues (we could not use the FPH during spa mode, so we either turned off the A/C inside or turned off the FPH controller....no we don't need to do that).

5. Ensure you install a Water FLOW cutoff valve. It does not come with the HOTSPOT FPH but the controller does have a spot for the cutoff wires. This will ensure that if it does not sense water, the controller will default to AIR COOL on the condenser. This would essentially stop any of the overheat complaints from the other post. I learned this from oneamaruluv...he is also here in Tampa, and we worked together to get out systems dialed in....by sharing in lessons learned.

- - - Updated - - -

All my neighbors love our constant water temperature in our pool water, and are looking into getting a HOTSPOT FPH. Especially, since they had issues with their previous solar installation due to roof leak.

I will tell you that its comparable to solar heat. My other neighbor has solar heat, and he an I are always comparing temps. His pool faces south (all day heat) and mine faces north (and shade from house). So I still think I come out ahead, as he has an advantage with all day heat from the sun.

Once we get into the cooler months, we will determine which works better between the two. Again our location is Tampa, Fl....which is crucial to understand, that there are several variables to consider....not each installation or application is the same.