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Thread: Hotspot FPH AC heat reclamation pool heater - a review!

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    Hotspot FPH AC heat reclamation pool heater - a review!

    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.
    16 x 32 18,000 gal IG vinyl pool. 1.5HP SuperFlo VS pump. Hayward C4030 425 sq ft cartridge filter. Hotspot FPH heat reclamation pool heater.

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    Mod Squad JVTrain's Avatar
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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Very interesting concept that I had not heard of before. Seems to be a very good idea for stabilizing pool temperature at a slightly higher level. My pool is consistently 76-78 degrees in the summer. No solar cover (yet). I have an old Teledyne Laars natural gas pool heater but I don't run it except very occasionally when we're having a large gathering. It would be great to stabilize it at a higher temperature without adding a solar heater. I would imagine that with a solar cover and this device, the average temperature would be appreciably higher.

    Thanks for sharing a keep us updated with the device function and longevity.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Thanks for the comprehensive post. I would like even more information should you decide to post it.

    I've been thinking about this concept since I first read about the similarities between a pool heat pump and an air-conditioner. Only today discovered that there was actually a company making a product to make this work. The price seem astronomical. I must be missing something, but doesn't the FPH simply run the coils through water. Why does it cost $1,800? I have solar water panels on my roof that cost me under $800 and they must also cool my house, right? They run cool pool water up to the top of my house which then absorbs the heat from the sun and prevents the heat from the sun from heating up the roof and then heating up my house, right? (I have no way of measuring this, but it simply must be true. When operating on a hot day, these solar panels have a temperature differential of about 2 degrees. (i.e. the difference between the temperature of the water leaving the pool and the water coming back in.) While they might be slightly less efficient than the FPH, it seems to me that it must do much of the same thing (heat pool and cool house). Biggest problem with both these solutions (for me) is that I have time of day pricing for electricity and my cost of electricity in the middle of the day is 45 cents/kwh. Just running my pool pump with enough power to push water to the roof costs more than 50 cents/hour even though the solar heat is free.

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    The refrigerant coils in the blue heat exchanger canister are made of titanium to withstand the corrosive nature of chlorinated pool water. That's pretty expensive. Also, the controller unit does some fancy stuff, monitoring the temperature of the pool water, turning on/off the pool pump automatically, and switching the AC unit from fan cooled to water cooled mode depending on pool water set temperature.

    Plus, they probably want to make some money, which I don't begrudge them. Total cost for this system is pretty typical of pool heaters.

    Also, as an aside, I wanted to update this review. During the few warm days we've had around here, the heater has been able to get the pool temp up to 85 degrees! I'm thrilled we were able to hit the 84+ mark this season. Didn't think it would happen.
    16 x 32 18,000 gal IG vinyl pool. 1.5HP SuperFlo VS pump. Hayward C4030 425 sq ft cartridge filter. Hotspot FPH heat reclamation pool heater.

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Reading this topic. Very interesting. Just wonder how your pool season ended w this product. Were you able to continue using the pool through September. My AC is on the opposite side of the house, so this may be a problem but I'm looking into it!


    13000 gallon pool, SWG, DE Filter, 2 sheer descent waterfalls, built Jan 2014

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Joshii, I know you installed close to the end of the season, bu also very interested in performance. I also live in the NE (MD) and just looking to keep the pool 84 in the summer without spending a fortune on propane to heat my 45 x 20 (750 sq ft) pool.

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    I plan to open the pool in a couple weeks. I will keep you posted on how it performs, though in reality it will probably be a month or more until the heater is actually used.
    16 x 32 18,000 gal IG vinyl pool. 1.5HP SuperFlo VS pump. Hayward C4030 425 sq ft cartridge filter. Hotspot FPH heat reclamation pool heater.

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Thanks! My biggest issue right now is the fact that the ac units are about 125 feet away from my pool equipment. I have a 2 hp pump, and the guys at hotspot said it should work. I have 2 heat pumps right next to each other (5 and 4 ton). They suggested just hooking up my 5 ton should be able to keep my pool at 84 degrees if it runs for 7.5 hours a day. If I also hooked up my 4 ton that figure would go down to 4.5 hours. However, to have enough water flow for both units at that distance I would need 70 gpm and would probably need a bigger pump than 2hp. My only concern is doing all this and then not getting enough gain out of it. If I could be sure this would keep my pool 84 degrees in the summer I would buy it this second. Like you, I can't find any reviews online (other than your's of course)...

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Sounds like a very interesting setup I'm not taking away value of it but I live in the Northeast my heatpump easily maintained 86 88 degrees and it's simply not hot enough to run my air conditioning 7 hours a day.... Just making sure you understand heat pumps also work in the Northeast.
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Quote Originally Posted by steinre1 View Post
    Thanks! My biggest issue right now is the fact that the ac units are about 125 feet away from my pool equipment. I have a 2 hp pump, and the guys at hotspot said it should work. I have 2 heat pumps right next to each other (5 and 4 ton). They suggested just hooking up my 5 ton should be able to keep my pool at 84 degrees if it runs for 7.5 hours a day. If I also hooked up my 4 ton that figure would go down to 4.5 hours. However, to have enough water flow for both units at that distance I would need 70 gpm and would probably need a bigger pump than 2hp. My only concern is doing all this and then not getting enough gain out of it. If I could be sure this would keep my pool 84 degrees in the summer I would buy it this second. Like you, I can't find any reviews online (other than your's of course)...
    If I had two units I would definitely hook up both. You'll get lots of heat out of it, and it will also make both run more efficiently.

    However, 250 feet is a LOT of extra distance for the water to go. Could you instead run the refrigerant lines to the water, instead of vice-versa? You could even install the equipment in the middle as well.
    16 x 32 18,000 gal IG vinyl pool. 1.5HP SuperFlo VS pump. Hayward C4030 425 sq ft cartridge filter. Hotspot FPH heat reclamation pool heater.

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    elwood58's Avatar
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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Running the refrigerant lines a long distance will impact how much heat is available to transfer to the pool water. That refrigerant will be cooling down over that run length.
    19204 Gallon L Shape with a 10X10 2nd Step Baja Ledge. Intellichlor IC-40, IntellipH, Cartridge Filter, Pentair Heater/Chiller (Heat Pump). Tons of Deck with Deck Jets. Construction Complete 6/5/17.

    "If you don't measure it, you can't manage it!"

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Quote Originally Posted by elwood58 View Post
    Running the refrigerant lines a long distance will impact how much heat is available to transfer to the pool water. That refrigerant will be cooling down over that run length.
    According to the guys at Hotspot, the water must be run to the AC and not vice versa. I'm not sure if it has do with the refrigerant cooling down or another factor. In regards to running both units, there are 2 issues:

    1) Price - For the 1 x 5 ton Heat Pump unit, the hardware will cost me about $2200. If I run my 2nd heat pump, it is actually a separate unit (but using a single modified controller) and it will run about $3500.

    2) Considering the length of my run 125 ft one way (250 total), and needing 70 gpm pressure for both, I think I would definitely need to upgrade my 2 HP pump.

    If I move forward, my current plan is to start with installing a system for the 5 ton unit, but paying an extra $125 for the control unit that could control the 2nd unit if needed. If I end up liking the unit, but decide I need to tap into the second heat pump all I need to do is purchase the second unit and plumb it into my existing set up (and address any associated pump issues). Feel free to poke holes in my thinking...

    Joshii, you wouldn't happen to live in MD, would you? I know Hotspot says that any licensed HVAC tech should be able to handle it, but I would still feel more comfortable dealing with someone who has done this before.
    45 x 20 (31k gallon) free form, 2 HP Pentair WhiperFlo, 3/4 HP waterfall pump, Black Pearl Pebble Tec, Aqualcal SQ175 Heap Pump, Raypack RP405 Propane Heater

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    I think that's a fine plan. For the long runs, you may want to consider using much larger diameter pipe -- 3". That will cut down on the head loss due to the long runs.

    As for the HVAC contractor, no, I live in MA. Honestly, the piping is really straightforward. They're right -- any HVAC technician should be able to do it. The biggest obstacles you'll likely face is getting an HVAC contractor who wants to use his head and read some instructions. Most of these guys have so much work in the summer they have no reason to look for anything other than their usual bread and butter work. Getting a technician on board before the high season, when they're low on work, will be your best bet.
    16 x 32 18,000 gal IG vinyl pool. 1.5HP SuperFlo VS pump. Hayward C4030 425 sq ft cartridge filter. Hotspot FPH heat reclamation pool heater.

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    A system like this is marginal in MA, and not nearly as good a fit in MD. In MA you have some overlap in the pool heating and home AC seasons. In MD you have practically none. In MA most pools need some additional heat even in mid-summer, the time when home AC peaks. But in MD you might need a tiny amount of heat mid-summer or you might need nothing at all, depending on the year. In MD you need heat in May and September, times of year when home AC is minimal.

    The relative sizes of the load/supply sides is also very asymmetrical. Swimming pools need gigantic amounts of heat, far more than is available from a home AC system. At some level, every little bit helps, and it does, but to get that little bit you are installing a complex and expensive system of unknown reliability. For most people it is not going to be a good tradeoff.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Quote Originally Posted by JasonLion View Post
    A system like this is marginal in MA, and not nearly as good a fit in MD. In MA you have some overlap in the pool heating and home AC seasons. In MD you have practically none. In MA most pools need some additional heat even in mid-summer, the time when home AC peaks. But in MD you might need a tiny amount of heat mid-summer or you might need nothing at all, depending on the year. In MD you need heat in May and September, times of year when home AC is minimal.

    The relative sizes of the load/supply sides is also very asymmetrical. Swimming pools need gigantic amounts of heat, far more than is available from a home AC system. At some level, every little bit helps, and it does, but to get that little bit you are installing a complex and expensive system of unknown reliability. For most people it is not going to be a good tradeoff.
    JasonLion, I see you live right around the corner from me. I grew up in Silver Spring and live in Howard County now. Your argument is valid, but my goals are different than what you are addressing. I have a 31K gal pool (750 sq ft) that gets partial sun (11am-4pm). I am not concerned about extending the season in May or September. I have a propane heater that I can use if there is a weekend we want to use it then. What I want is a warm pool every day in June, July and August. By itself, I am lucky if I can get my pool to 80 degrees on its own. My family is not going near it unless it is at least 83-84 and preferably slightly warmer. Before you ask, no I do not have a solar cover. My pool has a rock wall on one side with multiple water falls (no place for a reel) and the wife acceptance factor on bubble wrap pretty much nixes that idea. I have not tried the liquid solar covers, which I know aren't great, but if it can get me a couple of degrees cheaply I should probably give it a shot. If I really wanted to keep my pool at 84 all summer, it would probably cost me at least 1k of propane a month.

    I am by no means completely sold on the hotspot system. My main concerns are the length of run, screwing with (and possibly voiding warranty) of my heat pump, and not knowing how much gain I will really see from it. But considering my goals, it sounds like an interesting solution. If I can spend 4kish up front to keep my pool in the mid 80s all Summer without any additional costs going forward, that is very compelling. The other option would be a solar heating system, but my roof is VERY high and the wife acceptance factor is working against that as well

    Again, I am open to any and all ideas and I appreciate the insight.
    45 x 20 (31k gallon) free form, 2 HP Pentair WhiperFlo, 3/4 HP waterfall pump, Black Pearl Pebble Tec, Aqualcal SQ175 Heap Pump, Raypack RP405 Propane Heater

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    Steinre1, I think you're right. JasonLion's concerns are pretty typical of what I've heard before installing, which is why I posted the review. I believe a pool and AC unit are actually well matched for maintaining a set temperature during the warm summer months. Definitely not as much at either end of the season for sure. That's the case for solar as well. But most people, even those living in Florida, could use a little bit of heat added to their pool during the summer. I actually think this unit is more ideally suited for warm locations than cold.

    I will know more come this swimming season and will be happy to share what I find out about its performance and reliability.

    Steinre1, as for the flow needs / 70gpm: I too was excessively worried about flow rate from my pump. I have an old 3/4hp pump. My FPH unit needs 35gpm minimum and I was worried whether it would provide that or not. But as it turns out it was a nonissue. I don't know what my flow rate is. But the AC refrigerant lines get plenty cool after running through the pool water, much cooler in fact than when the coils are air cooled. So I imagine even with my low water flow rate it is still above the minimum.
    16 x 32 18,000 gal IG vinyl pool. 1.5HP SuperFlo VS pump. Hayward C4030 425 sq ft cartridge filter. Hotspot FPH heat reclamation pool heater.

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    I'm in Derwood, MD, so right in that same neck of the woods as Jason and steinre1. I've been thinking about this as well. My pool is pretty heavily shaded, tall trees right all around the southern half of the yard, so it only gets a few hours of full sun per day. Last summer we ran our natural gas heater through most of the summer; the only time we didn't is when the temp outside was in the mid 90s, and you don't mind swimming in 80 degree water. Else we're heating it to 86 or so. We don't run the heater 24/7, just when we plan to swim on the weekends, so we end up not using the pool as much as we could during the week. And that's all with the added hassle of keeping a solar cover on all the time. Last year my natural gas bill through the summer is about the same as it was during the winter, so I think I'd get plenty of usage out of the FPH during peak A/C months. And if it cut down on the A/C bill as well, that'd be awesome.
    Maryland
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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    I just came across the Hotspot FPH yesterday, and on first look, it appears that this system might be perfectly matched to my needs. I run both my house A/C and my natural gas pool heater a LOT during the summer. From June through September or early October, I keep the pool at 88 degrees. This costs approximately $1,000 in natural gas. I also keep my house at 71 degrees, which uses a lot of A/C. I have separate A/C units for downstairs and upstairs. I'm not sure how big they are, but I would guess around 3 tons each. Where I live (suburb of Los Angeles), the daytime temperatures during most of the summer run around 100 (sometimes reaching as high as 110).

    One question I have is whether the FPH could maintain 88 degrees in the pool, especially if only connected to one A/C unit. I have been paying close attention yesterday and today to the heater operation (I have a thermometer in the pool that wirelessly transmits the pool temp to 0.1 degree to a receiving unit in the house). In the morning before the pool equipment turns on, the pool temp has been about 84, meaning it dropped 4 degrees overnight from when the pool equipment shut off the night before (the pool equipment currently runs about 7 hours a day). It takes close to 4 hours to reach 88 degrees. I believe the heater is about 250K BTU, so that's a million BTUs to recover temp. Isn't that more than the FPH supplies?

    Another concern is how much more my pool equipment will run with the FPH. My A/C probably runs a good chunk of the day, especially when it is hot out. So that means that my pool pump might run say 18 hours a day, instead of my usual 7. How much extra electricity cost will that add, compared to the energy savings inherent in the system (and will that wear and tear on the pump cause it to need replacing much sooner)?

    Although that extra energy cost for the pump might be offset by the better efficiency of the A/C from the water cooling -- but is that the case? Right now, on the very hot days, my upstairs A/C can't keep up -- despite being set for 71, the temp usually reaches 74 by mid-day, or even 75. Would that be remedied by the better efficiency? I guess that depends on whether the bottleneck is at the outside condenser end of the system, or is with the inside air handler capacity. I have no idea which is the case.

  19. Back To Top    #19

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    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    I've had an FPH running here in Southwest Florida (Naples) since late 2012, for 2.5 years now, loving it. I'll post a full review in a new thread soon, I'm just catching up to some TFP topics since I've not been a member for very long. Just a couple thoughts for now, and questions welcome...

    I use it here for all purposes mentioned, mostly to extend the comfortable swimming season and also to raise the pool temp even in the summer. Although we have some of the warmest "average" temps in the nation, my pool faces NE, and without heat (I have no other heater, no solar) the 11K gallon gunite pool never rose to more than 83 max on its own, even on the hottest days. When rainy or cloudy, lower of course - on its own. So, with the FPH, we set the PID to 85 and it tends to stay there no matter what, for 8 months or so. Last summer my wife was on a kick to have it warmer so we ran it between 88 and 90, just for fun, knowing also that doing so probably saves a few more bucks on A/C. A temporary, if large, spa.

    I can try to dig up some other examples of readings I've taken, but I know we had a December warm spell just after I installed the FPH and I put a compressor runtime monitor on it. Across a 6 day period, the 3 ton AC ran for about 4-5 hours per day and the pool temp rose from 67 to 82 across that period, 15 degrees or 2-3 degrees per day. The tough part is knowing how much I was losing to the air each day. If you know the loss (which goes up with pool temp increase), there is solid math to calculate expected performance - the FPH guys help with that, trust yes but verify better.

    For efficiency, I measured a 17% reduction in current draw - the condenser unit formerly drew 12 amps total (each leg of 220) – 11 for the compressor and 1 for the cooling fan (2.8 ton AC unit). Now current down to 10 amps for the compressor alone when in water cooled mode. I cannot speak to how or if that translates to better home cooling. The AC guy did say he noticed the reduced head pressure in water cooled mode - we agreed in theory to perhaps a corresponding extended compressor life. I tried to run some air inlet/outlet temperature differential tests before and after, but found the endeavor inconclusive. Indeed the condenser unit is very quiet without the fan running, and I added a compressor blanket just for kicks, quieter still.

    We now get an extra month or so on each end of the season, now able to swim from early March through part of November, but without any other heating source most of November through February remain un-swimmable. Still, the end result is I get a sure thing of 85 degree pool temp in summer (higher if we want) and a longer season (plus efficiency improvement) so it feels well worth the cost to me. The ultimate measure is that my wife is happy.

    I also agree the cost seemed high, all-in I think I spent about $5K, despite having done all plumbing and electric myself, and I did a lot to educate the AC guys as well. They were great, just unfamiliar with it, and FPH folks answered my many pesky and continuous questions. In any case the FPH seems rather unique, and until there is competition it seems one has to either accept it or reject it. Or if you're inventive, have your own exchanger fabricated - the rest is off the shelf stuff.

    We do run the AC a lot here, even in winter (I had home heat on for a total of 20 minutes last winter), so I solved the issue of the pool pump running a lot by dropping an additional $1K on a variable speed pump. With a 1 speed 220 volt pump you use the FPH control's 2-pole relay to send 220 to the pump (in parallel to pool timer, careful to not cross the poles or have electrician do it), and now with the variable speed pump it only uses one pole of the FPH relay - closing the remote contacts feed from the pump controller to tell the pump to come on. That's nice to ensure the pump comes on, but now I just run the pump 7x24 anyway, in 1200 RPM / 72 Watt mode, a savings there as well (although break even on the $1K pump is probably 4 years, assuming it lasts that long). As others alluded, there is a minimum flow rate to ensure the exchanger is cooling properly, I checked that but don't have the numbers handy. The pump is 50 feet from the AC & FPH exchanger, I ran 2" from my 1.5HP max pump.

    It seems to me there must be at least three bad things about running the refrigerant long distance versus the water. FPH folks said the same thing as others mentioned here, better to run the water farther (and use bigger pipe and pump HP as/if needed). First, I think the PVC is a good insulator so not much loss of heat, whereas the expensive copper lines would also dissipate heat on the way to the exchanger. Perhaps more importantly there might be a fair amount more refrigerant needed if running copper, and it seems best to have the amount of required refrigerant near equal when running in each mode. I asked the FPH guys about that - he did some math but I think it was mostly based on AC tonnage to match the exchanger size they sell you. It does tease the brain to think, unless the volume is identical, one mode or the other must suffer at least slightly from too much or too little refrigerant. Perhaps only slightly, so its ignored.

    When I have guests in the winter, I sometimes open windows and doors so I can run the AC to heat the pool without freezing us out. LOL. I have in mind an automated louver system that would direct the cool air out of the house when the pool wants heat and the home doesn't want AC, that way I would not have to buy another heater in order to extend the swimming season to a full 12 months.

    Another agreed point that folks have mentioned, it must be true that this would void any warranty on the original AC unit. I decided to accept that, mine is a bit older anyway and I figure to always just fix it. It does take me out of the market for the latest and greatest efficient AC system unless I want to void warranty on a new system - possible but tougher to swallow. To be fair, my efficiency gain might be offset by keeping an older AC unit, then again I avoid the cost of a new AC unit - while heating the pool.

    A minor thing, setting the temperature on the PID is not the simplest thing - passwords and two to five settings to change just to adjust the temperature. I don't know why that wasn't made to be more similar to most solar heat controllers. So I also bought another, smaller, cheaper PID ($20 I think) with its own temp sensor and display and mounted it inside the house, I'll add a switch to the main control box so I can select inside or outside control.

    Another minor thing, I was never totally pleased with the thermocouple temp sensing method recommended by the folks at FPH. In 2012 they were recommending you feed the thermocouple tubing down through the (assuming low voltage pool light) pool light conduit into the lightwell and have it stick out a bit from the light frame - not sure if that is still their recommendation. I could never get it pulled through there, not with the #10 bonding wire and low voltage cable at the same time. So I connected it to the PVC in a return line. It still varies with ambient air temp and sunlight (despite constant water flow), but that problem has plagued me on many other pools and various solar and other heaters for a long time - a matter perhaps for another post
    IG 11K gal gunite fresh water w/8 popup cleaners - Polaris Caretaker 5 port.
    Jandy JEP1.5 ePump, JEP-R wall mount. 7x24 @1200 rpm & 72 watts
    Hotspot Energy FPH “Free Pool Heat” from water-cooled home A/C condenser.
    Hayward 120 sq ft cartr filter Unicel C-8412. Well fill - Terminox iron filter.
    TF-100 monthly / Taylor K-1000 daily / ColorQ Pro-7 Digital/Optical

  20. Back To Top    #20

    Join Date
    Jul 2015
    Location
    Montreal, Quebec
    Posts
    46

    Re: Hotspot FPH AC heat reclamation pool heater - a review!

    So glad I found this thread! Was about to start one of my own asking if anyone had experience with this.

    Quote Originally Posted by nuttyp View Post
    Or if you're inventive, have your own exchanger fabricated - the rest is off the shelf stuff.
    I'd suggest buying an off-the-shelf exchanger. Either parts from pool heat pumps or through HVAC specialists. I've corresponded with a man in Texas who built his own system. His calculations had him paying off the system on A/C efficiency alone. So much so that he heated the pool in the daytime while cooling the house, and chilled the pool at night using the condenser coils and condenser fan.
    I corresponded with him months ago. Here's his website describing his DIY approach:
    Central Air Pool Heater - Nathan Strattons Homepage

    For those with long runs between the pool and a/c or heatpump, why not install a booster pump to run when the a/c is running?

    If I get my pool running (different thread altogether) I definately want to try doing the same with my house and pool. Can't stand the idea of installing another heat pump on my property for the pool.
    Piped right, the house heat pump could use the pool for house cooling and also use full power to heat the pool if desired.
    I've even started to sketch out how to use all the overheated attic air in the house to efficiently heat the pool using the heat pump.

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