Trouble free high efficiency pool heater?

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robotrobinson

robotrobinson

Bronze Supporter
Apr 22, 2022
12
Pinole, CA
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
I wish to add an uncovered, outdoor natural gas heater to daily warm my 20,000-gallon pool with pool cover during the winter in San Francisco East Bay.
My roof top water solar keeps the pool warm enough April 15 - Oct 15.
Winter outdoor temperatures are typically 45F low to 60F high. I can swim daily down to 65F pool temperature.

My impression is that high-efficiency heaters often require significant attention and significant annual maintenance to keep them running properly.
Does anyone have a trouble-free high efficiency (93%+) natural gas heater that they have been using daily for over 5 years and love it?

Thanks,
Chris
 
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robotrobinson said:
I wish to add an uncovered, outdoor natural gas heater to daily warm my 20,000-gallon pool with pool cover during the winter in San Francisco East Bay.
My roof top water solar keeps the pool warm enough April 15 - Oct 15.
Winter outdoor temperatures are typically 45F low to 60F high. I can swim daily down to 65F pool temperature.

My impression is that high-efficiency heaters often require significant attention and significant annual maintenance to keep them running properly.
Does anyone have a trouble-free high efficiency (93%+) natural gas heater that they have been using daily for over 5 years and love it?

Thanks,
Chris
Click to expand...
I don't know about HE heaters, so I may be talking out my backside. I have been using my Pentair MasterTemp 400 weekly for the last 5 years (unless freeze protection is enabled and it doesn't run the schedule). The only issue I have had, that wasn't due to a lightning strike, is the thermal regulator went out. Simple fix.

My opinion, coming from an industrial combustion equipment background is that most pool heaters fail because they sit. They need to be fired up regularly so that they can be exercised. Which is one reason I have mine scheduled to fire every week for at least 2 hours for my spa. It allows the water temp to get above the 68F threshold mentioned in the instructions, and it allows me to see that everything is working as it should so that I can address any maintenance that might be needed, before I am up against a weekend swim party or something like that.

I'm sure others will be around soon to weigh in as well.

Good luck!

--Jeff
 
What 93+% efficiency pool heaters are you considering?
 
robotrobinson said:
I would consider any - I'm thinking 400K BTU, but open to any that someone has had a good experience with.
Click to expand...
What if I tell you there are none with a 5 year history of daily use?

Where did you get that criteria?
 
They are expensive to buy and to repair.

The complexity means a lot of maintenance.

Why are NatGas pool heaters low efficiency?

I just replaced by pool heater with a new Raypak unit. This heater had a sticker saying it had an efficiency rating of 82%. This seems typical for pool heaters. My furnace is high efficiency and has a rating of 97. Does this mean that per unit of heat my pool heater uses way more NatGas per...
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ETi® 400 High-Efficiency Pool & Spa Heater

Pentair ETi 400 High Efficiency Spa and Pool heater has 96% thermal efficiency and is the first gas pool heater with direct-fire titanium heat exchanger.
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Professional Series X94 – Raypak

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If you use 400,000 btu/hr of gas, you get 336,000 btu/hr of heat added to the pool at 84% efficiency.

At $20.00 per 1,000 cubic feet, that is $8.00 per hour or $23.81 per 1 Million BTU added to the pool.

If you use 400,000 btu/hr of gas, you get 376,000 btu/hr of heat added to the pool at 94% efficiency.

At $20.00 per 1,000 cubic feet, that is $8.00 per hour or $21.28 per 1 Million BTU added to the pool.

For every 1 million btu of heat added to the pool, you save $2.53.

So, you really need to know how much heat you will use to see the savings.

If a heater runs for 5 hours per day at 336,000 btu/hr of heat added to the pool at 84% efficiency, then that is $40.00 per day at 1.68 million BTU per day or an extra cost of $4.25 per day (Compared to a 94% efficient model).

If a heater runs for 4.47 hours per day at 376,000 btu/hr of heat added to the pool at 94% efficiency, then that is $35.75 per day at 1.68 million BTU per day or a savings of $4.25 per day (Compared to an 84% efficient Model).

If the water in the pool weighs 250,000 lbs (30,000 gallons), then that is 6.72 degrees added per day.

For 1,000 days of operation, that's 1.68 Billion BTUs added to the pool, which is a savings of $4,250.00 in gas.

For 1,000 days of operation at 1.68 Million BTU added to the pool per day, you save a total of 530 hours of heater runtime, which is $4,240.00 at $8.00 per hour ($20.00 per 1,000 cubic feet of gas).

So, you have to look at the cost difference for purchase, maintenance, repair etc. and how much the heater is used.

If the savings are higher than the cost difference before the heater needs to be replaced, then it might be worthwhile.

For a commercial operation where the pool is always heated, it might be worthwhile.

For a low use residential pool, the extra cost is probably not worthwhile.
 
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ajw22 said:
What if I tell you there are none with a 5 year history of daily use?

Where did you get that criteria?
Click to expand...
I made it up. I would love to swim daily during the winter. April 15 - Oct 15 I would use the roof top solar to heat my pool, not a natural gas heater. My impression is that high-efficiency heaters often require significant attention and significant annual maintenance to keep them running properly. I was hoping to find a trouble-free high efficiency natural gas heater someone has long-term experience with and would highly recommend.
 
robotrobinson said:
I was hoping to find a trouble-free high efficiency natural gas heater someone has long-term experience with and would highly recommend.
Click to expand...
Unlikely to pay off for a residential customer.

If you need service, it is unlikely that you would find a qualified service person.

Pool Service People can barely work on normal residential units.

A High Efficiency Unit would be outside their competence.

Most HVAC People also have little experience and often won't work on "Pool" Equipment.
 
JamesW said:
They are expensive to buy and to repair.

The complexity means a lot of maintenance.
Click to expand...
That was my impression. I may instead go for a heat pump - perhaps AquaCal SQ166R or SQ225.
I may also get the Raypak R406A 009219 natural gas heater to get me through when it gets too cold for the heat pump.

My impression is that folks have had good experience with these heat pumps and heater with minimal maintenance.

My 20,000 gallon pool was my daily go-to exercise until temps crossed below my 65 degree morning swim threshold on Oct 28.
I estimate it would cost me $4.24/therm-hour for a 7.2 kw 140K BTU heat pump that can deliver 85K BTU at 50F at a current winter electric rate of ~ $0.50/kwhr (rates are rising, and higher in the summer).
I estimate it would cost me $3.24/therm-hour for an 85% efficient gas heater at a variable winter natural gas rate of ~$2.75/gas therm.
I use rooftop solar water to keep the pool swimmable mid-April to mid-Oct.
I have electric and gas already available at the pump/filter.
It's all uncovered.

I have roof top PV, but not much leftover when I use space heaters to avoid running the furnace.

Thanks,

Chris
 
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JamesW said:
How many total btu would you add to the pool per year?

What is your natural gas cost per 1,000 cubic feet?
Click to expand...
I don't know how many btus I would add to the pool each year - so many variables and too many unknowns.
I have a 20,000 gallon pool and want to go swimming daily but no colder than 65F.
Wild guess: 7 therms a day * 180 days / winter = 1260 therms a year * 100,000 BTU/therm = 126,000,000 BTU / year?
My natural gas rates, (currently $2.62 / therm), over last year varied $1.86 to $2.90 / therm = $2.90 / 100 cubic ft. = $29 / 1000 cubic ft?
 
JamesW said:
What is your Solar Power Rate per 1 Million BTU?
Click to expand...
I don't know what "Solar Power Rate" is.
I am under California NEM 2.0 for solar.
As a rough estimate, on an annual basis, I pay $0 for anything I generate and use.
On an annual basis, I receive close to $0 for anything I generate more than I use.
Since installing the panels, I have a small surplus, on an annual basis.
I put this surplus to use by running space heaters to reduce my natural gas furnace bill.

I'm essentially consuming, on an annual basis, what I use. The utility does a true-up each year. If I use more than I use, it costs me roughly $0.50 / kwhr, and rates are going up. That is essentially what it will cost me to run the heat pump. The Aquacal heat pumps are on the order of 7 kw, and generate 85K - 140K BTU, depending upon temp/humidity. I would run it only in the winter, so closer to 85K BTU.

I cannot add much more solar without triggering putting me under NEM 3.0.
Under 3.0 I would no longer receive full credit for the energy my solar produces.
 

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