Tankless Electric Pool Heater for In Ground Pool

Scrutinizer

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Oct 3, 2015
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Middletown, Ohio
This is my first post. I have a 19,300 gallon in ground freshwater swimming pool in southwest Ohio. The only problem I have with it is I don't get to use it as much as I'd like because the water doesn't get warm enough. This swimming season (Memorial Day to Labor Day) I got maybe two weeks when the temps got into the 80's.

So, I'm looking into installing a heater. We do not have natural gas and the logistics of install a propane heater are prohibitive. My only power option is electric. From what I understand, a heat pump might be okay when the air temps are warm but not so much when they are colder. That brings me to looking at a tankless water heater. Below is a website showing the unit I am considering tapping into the pools water system. It heats 5.3 gpm. In your opinions, what do you think? What can I expect to happen?

http://www.homedepot.com/p/EcoSmart-27-kW-Self-Modulating-5-3-GPM-Electric-Tankless-Water-Heater-ECO-27/203316218
 

duraleigh

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What can I expect to happen?
nothing very good, I'm afraid.

Without doing the math, your electrical consumption may require a bank loan.

A serious attempt at getting the heat you want would be to look at solar. Hundreds of users here on the forum can help.
 

Leebo

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Hello, and welcome to TFP!!!

What are your main expectations of heating the pool? Do you wish to heat it up to 85ish most of the year, extend your season by keeping the temps in the 80's from Early May-late Sept, or both?? Do you currently use a solar cover???
 

JohnT

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Welcome to TFP!

I'm just a tiny bit further south than you are, so we probably have very similar weather. I have solar, and my pool was 88 a week ago Thursday, and 85 that Friday and Saturday. I have about $1200 in my system, and it has little to no operating cost. I think this was my 8th season with the system, so I'm at about $150 a year heating cost, with no sign that the panels won't be around for several more years. If it went bad now, I'd replace it with the exact same thing.

The tankless heater is really out of its league trying to heat a pool. Just to make the math easy, let's say the tankless heats 5gpm. 70 degrees to 120 degrees is a 50 degree rise for 40 pounds of water. 200BTU/minute. That's 12,000BTU/hr. Residential pool heaters are on the order of 400,000BTU/hr.

If you aren't already using one, a solar blanket is the best first step. It will probably get you 5 degrees warmer.
 

JoyfulNoise

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Unfortunately, tankless electric water heaters are not designed for pool use. They are a low flow rate, large temperature delta design. Pool heaters, by contrast, operate at high flow rates and smaller temperature changes. In order to hook it up to a pool, you'd have to bypass most of the water flow away from the heater or else you'd completely choke off your pool water pump. Installing one would be a total waste of time and money.

I have a 400,000 BTU/hr Nat gas heater and a 16,000 gal pool. If I run that heater full bore on my pool, the best it can achieve is a few degrees per hour and not more than 5-6F total rise without a solar blanket due to evaporative heat loss. Suffice it to say, the Nat gas heater is mainly for spa use (650 gallon).

Solar is your best option. In my local market, a full solar installation runs $3k-$6k depending on equipment needs. It's on my bucket-list of pool upgrades.


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Scrutinizer

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Oct 3, 2015
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Middletown, Ohio
Hello, and welcome to TFP!!!

What are your main expectations of heating the pool? Do you wish to heat it up to 85ish most of the year, extend your season by keeping the temps in the 80's from Early May-late Sept, or both?? Do you currently use a solar cover???


During most of the summer the pool gets to much shade and the water temps stay in the upper 70's. That is to cold for my old bones. I want the heater to raise the water temp 10 degrees.

Not using solar power.
 

Scrutinizer

New member
Oct 3, 2015
3
Middletown, Ohio
Unfortunately, tankless electric water heaters are not designed for pool use. They are a low flow rate, large temperature delta design. Pool heaters, by contrast, operate at high flow rates and smaller temperature changes. In order to hook it up to a pool, you'd have to bypass most of the water flow away from the heater or else you'd completely choke off your pool water pump. Installing one would be a total waste of time and money.

I have a 400,000 BTU/hr Nat gas heater and a 16,000 gal pool. If I run that heater full bore on my pool, the best it can achieve is a few degrees per hour and not more than 5-6F total rise without a solar blanket due to evaporative heat loss. Suffice it to say, the Nat gas heater is mainly for spa use (650 gallon).

Solar is your best option. In my local market, a full solar installation runs $3k-$6k depending on equipment needs. It's on my bucket-list of pool upgrades.


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Thanks for the advice. This particular tankless heater has its own flow regulator but the more I think about it I might as well run a hose from my house water heater to the pool and open the valve. I'd get the same unsatisfactory results. I'm going to look at the solar option.
 

duraleigh

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I'd get the same unsatisfactory results.
Correct. Most of the solar stuff is not very effective (in terms of payback) but solar heat for a pool is an exception.
 

Leebo

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I'd too vote to look at solar, but if your still concerned I'd take another look at a heat pump. In our case just east of you we had too much shade to make solar an option (pools in the middle of heavy woods). We went a heat pump and was able to maintain a temp of about 86° all of August and Sept and the power went up about $100 for both months. Regardless of your choice, a solar cover is a MUST!
 

JoyfulNoise

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Regardless of your choice, a solar cover is a MUST!

+1 ^^^^^^

Even here in the sunny & hot southwest, I was told by at least two solar companies that pool water solar heating only works well on a pool with a bubble blanket. No solar cover and the best you'd get is a couple of degrees. With a solar blanket and you can easily raise your pool water 10-15F. It's all controlled by evaporative heat loss.


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4knights

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Aug 19, 2012
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I saw a heating unit on YouTube that attached to you home A/C system. It used the heat generated from the condesor to heat the pool. Possibly the alternative you need? Same electrical source providing two functions
 

JoyfulNoise

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I saw a heating unit on YouTube that attached to you home A/C system. It used the heat generated from the condesor to heat the pool. Possibly the alternative you need? Same electrical source providing two functions

I believe this has been discussed in other threads and if memory serves me, @leebo already brought up a good point - these units operate at the wrong time of the year relative to the pool's heating needs. You typically run A/C units in the summer when your pool water doesn't typically need a lot of heat and you don't run your A/C in the cooler months because your house does not need cooling. Also, the amount of heat energy stored in your hot home air is much smaller than the energy needed to heat pool water. So you have to run your A/C when you don't need to and the heating power is very undersized. Not a good idea in my opinion.


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