Hotspot FPH AC heat reclamation pool heater - a review!

[Joshii]

I'm not understanding this whole subthread. The FPH unit is $1800, which is expensive, but nearly as expensive as the labor to install it. If you're DIY'ing it - you'll save a ton doing the labor yourself. Will you really save a ton more by trying to DIY the most tricky components?

 

[jerryt]

I am pretty close to pulling the trigger on buying a heat exchanger for $600, piping it up, and just seeing what happens.

I was going to install the two condensing coils back to back. Sure would make things simpler. As you said, you could use pump speeds to tweak the charge level...

You should try. I would like is know that it works and there are little to no issues running two condensers in series (No balance coil).

Another issue is what happens when we need to change the house A/C, does anyone think that a standard A/C company will deal with these valves and matching the "Balance Coil" to the new condensing unit ?? Wiring in a fan disconnect relay??

I think on paper, the "Balance Coil" allows to perfectly match the operation of the two modes, but in real life, people do not spend the time to match the "Balance Coil" properly, and then there is the effects of pump speeds..., pump changes, filter new or dirty, etc

Why not go simple

 

[chillermonster]

I'm not understanding this whole subthread. The FPH unit is $1800, which is expensive, but nearly as expensive as the labor to install it. If you're DIY'ing it - you'll save a ton doing the labor yourself. Will you really save a ton more by trying to DIY the most tricky components?

You can get the heat exchanger as a replacement part for a heat pump pool heater for like $600 online. Hotspot sells you the heat exchanger, the changeover valve, and the controller as a package. I'm not interested in trying to piece together all of the controls, so I'm trying to figure out if the refrigeration cycle will work right with the two condensers (FPH + air cooled condenser) operating in series all the time rather than changing over.

I can can get my hands on refrigerant reclaim equipment, I know how to braze, and I still have my refrigeration license, so I can pipe the FPH in myself and have only $600 + a Saturday of sunk cost.

There is definitely a risk of creating a problem with my A/C as this appears to be totally unproven based on my research so far. I may try to call the A/C manufacturer's tech support line as one last attempt to solve the riddle.

 

[NJdiy]

Yes putting the water cooled condenser before the air cooled condenser in series will eliminate the need for a valve and controls. But the problem is what kind of damage will the water cooled condenser have if the pool pump fails or doesn’t turn on for some reason ?

 

[NJdiy]

I added a "Purge Timer" to my installation. I noticed that most all my A/C use (Mostly at night) the compressor(s) are called for in cycles with less then 15 minutes between cycles. I don't mind the compressors cycling because they must, but I prefer to keep the pump(s) and Hotspot valves engaged during those 15 minutes of compressor off cycle. It was to accomplish a couple of things;
1) Needless cycling of hotspot valves,
2) Freon moving back to air side when valves release,
3) Purging of latent heat in the exchanger,
4) Ichem requires a 15 minutes pause at startup (Which also pauses intellichlor), so "Purge Timer" keeps chemicals at steady state.

Also added adjustable compressor timers, so that hotspot system could be running before compressors started.

The Sporlan valve that comes with the Hotspot FPH depends on the pressure difference created by the compressor to switch the gas paths. I don't know if simply keeping its solenoid energized while the compressor is off will prevent the freon from moving back to the air side.

 

[NJdiy]

Different start sequence. Currently, the way FPH controller works is that when the house thermostat calls for for cooling, outside unit starts the usual way, the controller turns on the pool pump and samples water temperature for 25 seconds, then if water temperature is below set point, turns on the heat reclaim valve to circuit refrigerant through the water cooled exchanger and turns off the fan. IMO, there are few problems with this : heat is wasted for 25 seconds, fan turns on and off unnecessarily, and the biggest problem is the valve changing the direction of refrigerant while compressor is on can cause liquid hammer and potentially damage the compressor.
I propose this sequence. House thermostat call for cooling starts pool pump and energizes the heat reclaim valve coil and solenoid coil and turns off fan but does not start the compressor. FPH controller samples water temperature for 25 seconds, if pool needs heat, starts the compressor, if not de-energizes heat reclaim valve coil and solenoid coil and starts compressor with fan and turns pool pump off.

So guys, here I am posting the Controller circuit that I came up with to achieve the above. You have to cut the thermostat wire going into the outdoor AC unit and connect it to the controller and then the controller connects to the other end of the thermostat wire going into the outdoor unit. Please poke holes in the circuit plan my if any. Thanks !!

 

[newpoolj]

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.

@Joshii Now that you're a few years in with the Hotspot, how has it held up? And along the same lines, has it caused any trouble for your AC? Anything you'd change?

 

[Joshii]

@Joshii Now that you're a few years in with the Hotspot, how has it held up? And along the same lines, has it caused any trouble for your AC? Anything you'd change?

Still love it! It's working great still with no issues. No problem with the AC at all. The one thing I'd change - and they may have already done it - is to add a flow sensor. If my pump trips for some reason, my FPH will still call for water cooling. This has lead twice in all these years to the AC overheat safety limiter tripping. That's a thing built into all AC units. No issue caused by that either time. But would be better for the FPH to know there's no water flowing and air-cool the refrigerant. Aside from that, I can't think of a thing to change. It just works.

 

[Belikin]

Still love it! It's working great still with no issues. No problem with the AC at all. The one thing I'd change - and they may have already done it - is to add a flow sensor. If my pump trips for some reason, my FPH will still call for water cooling. This has lead twice in all these years to the AC overheat safety limiter tripping. That's a thing built into all AC units. No issue caused by that either time. But would be better for the FPH to know there's no water flowing and air-cool the refrigerant. Aside from that, I can't think of a thing to change. It just works.

Joshii, I just got mine finally fully installed about a week ago and LOVE IT as well so far! I can confirm that the flow sensor port has been added and is even pre-labeled from the factory on my new unit. It doesn't come with the flow sensor itself however so my AC guy is going to install it for me as soon as I can procure it from whereever for him to do so.
Newpoolj, here in northern Florida, I've got mine set at 87 degrees as the called for temp and with about 4 hours of AC runtime per day it's having no problem meeting that demand and keeping my pool a wonderful 87 degrees!

 

[newpoolj]

Still love it! It's working great still with no issues. No problem with the AC at all. The one thing I'd change - and they may have already done it - is to add a flow sensor. If my pump trips for some reason, my FPH will still call for water cooling. This has lead twice in all these years to the AC overheat safety limiter tripping. That's a thing built into all AC units. No issue caused by that either time. But would be better for the FPH to know there's no water flowing and air-cool the refrigerant. Aside from that, I can't think of a thing to change. It just works.

Great to hear! I'm planning a pool build presently. My builder said they'd never heard of the Hotspot, but I'm thinking I'll try it out anyways since I don't have any other good heating options (limited roof, super expensive energy costs). I'm curious, what's causing your pump to trip? Is it unrelated?

Joshii, I just got mine finally fully installed about a week ago and LOVE IT as well so far! I can confirm that the flow sensor port has been added and is even pre-labeled from the factory on my new unit. It doesn't come with the flow sensor itself however so my AC guy is going to install it for me as soon as I can procure it from whereever for him to do so.
Newpoolj, here in northern Florida, I've got mine set at 87 degrees as the called for temp and with about 4 hours of AC runtime per day it's having no problem meeting that demand and keeping my pool a wonderful 87 degrees!

@Belikin Where is the flow sensor port exactly? Do you know what sensor you'd use or how to program it?

 

[Belikin]

@Belikin Where is the flow sensor port exactly? Do you know what sensor you'd use or how to program it?
[/QUOTE]

On the top of the heat exchanger there is a plugged port that is available and labeled "water flow outlet" that was my intention to use. I spoke with the Hotspot folks today however and they say it's better to plant the flow switch in the PVC by adding a joint with a sensor well on it and they recommended the Harwil Q8N series flow switches. As for programinng, it's a simple open close paddle that gets triggered by the flow of water and then either closes or opens the circuit. So, we'll tie that in as a circuit break in the line that fires the solenoid to divert the R410 over to the heat exchanger rather than the aircool coil. So, if there is no water flow the kick over of the solenoid simply won't occur, thereby protecting the compressor.

 

[Joshii]

The tripping pump was unrelated to the FPH. Just a touchy GFCI.

 

[Katodude]

How well would something like this work when the pool is really hot? Say over 90 degrees? Can it get the water that hot, and will it still be efficient with pool water that hot?

 

[Joshii]

How well would something like this work when the pool is really hot? Say over 90 degrees? Can it get the water that hot, and will it still be efficient with pool water that hot?

So - this is another thing I would change on the FPH. It is too hard to reprogram the set points. It *could* be as easy as a thermostat. Up and down changes the set point. But it's not. It's confusing as heck. I'm not touching it. The cutoff temp is 90 and I leave it there. It was there all summer and the AC was still better than on air-cooled mode. It works just fine.

 

[newpoolj]

A few questions for @Joshii or others who have installed a hotspot:

- How many hours a day do you run your pump? Does the pump speed matter?
- How did you go about finding an HVAC technician who would take on this install. What did you ask them?

 

[drglanton]

Hello. We love ours.
1. I run my pump with normal variable settings when the AC is not engaged. My system is set to increase speed when the system activates.
2. I searched high and low for an HVAC person. I finally found someone who understand this was a side job and they we not want expected to provide warranty. Basically it was service and the owners risk. I stood with him and walked him through everything. He had a lot of questions but I got us through it.

You will have a lot of questions. Feel free to reach out.

 

[Joshii]

A few questions for @Joshii or others who have installed a hotspot:

- How many hours a day do you run your pump? Does the pump speed matter?
- How did you go about finding an HVAC technician who would take on this install. What did you ask them?

I have a VS pump that I run 24x7 at very low speed. No issues with the FPH.

Finding the HVAC guy is tough. Others have given good advice. I was able to use the company that was in the "This Old House" segment. Lucky me!

 

[Belikin]

A few questions for @Joshii or others who have installed a hotspot:

- How many hours a day do you run your pump? Does the pump speed matter?
- How did you go about finding an HVAC technician who would take on this install. What did you ask them?

I ended up putting mine on a seperate single speed pump that only runs when the AC is on and the system is calling for heat. My primary pool pump is a VSF and am only running that for a few hours a day right now.
Finding the HVAC technician was difficult . I had a guy who agreed to do it and then looked at in depth and backed out. Finally found a technician who, like DrGlanton said, was willing to learn it and understood that I understood I was taking this additional work as a risk on my AC system. We've been VERY VERY happy and I was swimming 88 degree water all the way up until mid november here in NE Florida.
FWIW, the guys at Hotspot were AMAZING and were super helpful with my AC guy even going so far as to take personal phone calls into the evening while my guy worked through the gaps in his knowledge. I've since referred two more new pool owners who are installing Hotspot and using my AC guy.

 

[newpoolj]

Has anyone tried incorporating their Hotspot control into Jandy or Pentair automation (Aqualink, etc)?

 

[drglanton]

Yes. I have mine with Pentair. Check my thread and let me know if you have any questions. It works perfectly.