Help Sizing and Selecting Natural Gas Heater for AGP

I hate to watch my family go use the friend's pool because ours is too cold! :(

I could use some help picking the right heater. My pool surface area is about 500 sq. ft. with a volume of about 1900 cu. ft. (on-ground 24' round) and I live in RI so I'll want to raise the temp 20-25 deg. F. I have Natural Gas at the house and do not want to deal with Propane tanks.

I'm looking for something reliable (fewer fancy features a plus), efficient, and fairly quiet (in that order).

I'd be thankful for your suggestions and experience!

You might consider a heat pump. They're more expensive to buy but cheaper to operate and require only electrical and pool water connection - no gas plumbing. Solar is also cheaper to operate but only heats when the sun shines.

Thanks BigDave. I had considered a heat pump, but I do not believe I will be able to recover from 58 degree June nights for pool use during the day. m I wrong about this?

Hi bottomcat I would suggest a 150,000 BTU heater for your application as this size unit would give you a 30 degree temperature rise. The unit I like is the Raypak 014784 heater, this is a 150,000 BTU unit and in my experience has been very reliable. I would also highly recommend using a solar blanket when your pool is not in use as evaporation accounts for nearly 70% of the heat loss in your pool.

Thanks patrick3229. Do you know the efficiency and dB level of this unit?

I've seen heat pump claims to operate down to 50F.
I agree about the thermal blanket, It makes a huge difference in my pool with solar panels.

BigDave, I have also seen that they will operate at fairly low temperatures, but that they simply are not capable of bringing the water up substantially over a reasonable time frame. What are you using there in New Jersey besides the solar panels? How long is your swim season?

Anyone else have any heaters that they have been happy with or ones that have been poor?

The efficiency rating on that Raypak heater is 82% unfortunately I do not have dB rating.

In regards to the heat pumps.... Heat pumps draw in the outside air to heat the water so as the outside temperature drops the efficiency and effectiveness of the heat pump drops, typically all of the performance data on the heat pumps is set at an outside temperature of 82 degrees. So even if the unit can work at the lower temperature they will be far less efficient then when operating at warmer temperatures.

patrick3229, I agree. I love the idea of a heat pump (and hate the idea of paying a big gas bill) but with the money already invested in the pool and deck, I want it to be comfy!

What factors contribute towards reliability in your opinion?

@bottomcat: how do you expect to use the pool / heater when the weather turns chilly? Are you thinking you'll heat it when you want to swim or keep it warm so it'll be ready when you are?

Me, I don't open until until memorial day because of the pollen and pods. The swim season is pretty much over when the kids return to school school after Labor Day. Maybe, if the weather is with us we can sneak a dip for a week or two after school starts.

@BigDave: I'm not really sure. I guess a combination of both. When the kids are home from school, I'll probably set it to stay at 75 or so and leave it on 24/7 for a few weeks at least. If we get busy doing other things, then maybe I'd just turn it on the night before a swim day. It will depend on how much it ends up costing to heat.

The consensus we've sort of reached here is that the Hayward Universal series is preferable, for several reasons:
+ It seems to be pretty reliable
+ It's salt-compatible at no extra expense
+ It's powered draft, which means it's not affected by wind and is a bit more efficient.
+ It's very compact

The positive consensus was not very strong; the strong agreement was that you should NOT get a StaRite heater. ;)

If you go through the Amazon reviews on heaters, a number of the negative reviews result from people not getting the sizing right, or not understanding the venting and gas supply requirements. That's not a buyer error, that has nothing to do with Hayward (or any other maker), other than suggesting that they might want to do more to educate consumers.

I've installed a number of these, and they have performed well. I will caution that salt-compatible is not salt-proof on the Hayward or any other heater. It's hard to get a metal with good conductivity (for heat exchange) and good corrosion resistance. High levels of salt WILL accelerate corrosion on these heaters, too. I had to replace a 4 year old continuous duty (365 days/year) heater just this spring. Because it is on a heavily used outdoor kiddie pool that leaks, salt levels are erratic and often high.

There is complaint that I've seen several times: sometimes when these heaters are installed outdoors, water leaks through the panel and into the controls, resulting in pricey repairs. The heaters I've installed are indoors, but if I installed one outdoors, I'd cut a piece of stainless or galvanized sheet to lay over the front edge of the heater and protect the panel.

The Hayward Universal models are all marketed for in-ground pools, but the 150 or 250 will work just as well on most AG pools.

Natural gas models:

• Hayward H300FDN Universal H-Series Low Nox 300,000-BTU Natural Gas Pool Heater
• Hayward H250FDN Universal H-Series Low Nox 250,000-BTU Natural Gas Pool Heater
• Hayward H200FDN Universal H-Series Low Nox 200,000-BTU Natural Gas Pool Heater
• Hayward H150FDN Universal H-Series Low Nox 150,000-BTU Natural Gas Pool Heater

In regards to this question "What factors contribute towards reliability in your opinion?" I would say the manufacture actually making the heater we have dealt with all of the major heater manufactures and we have had very little warranty issues with Raypak and Hayward. I tend to like Raypak a little more as that is all they do is pool heaters and nothing else so they are very focused on this product line.

As far as specific features for reliability you may consider a Cupro Nickel heat exchanger. The main component of a gas heater and by far the most expensive part if it needs to be replaced is the heat exchanger. Most heaters come standard with a copper heat exchanger however you can typically upgrade for a few hundred dollars more to a Cupro Nickel heat exchanger which is a heavy duty heat exchanger which holds up better against your pools chemically treated water, this is a good option if you have a salt pool as well.

The cupro-nickel exchanger refers to is standard on the Hayward Universal models; on other makes of heater, it's an upgrade or a different model.

Doc & Pat: Very helpful information. I am leaning towards the Hayward 250k based on price, availability, reviews, and CuNi. I am a little concerned about the water infiltration issues, but I guess I can fabricate something.

Do you recommend draining the heater when not in use?

Yes, it's best to be drained.

I'd check the manual carefully, to make sure you have FULLY winterized it, and that there's not some pocket of water left somewhere that can cause problems.

I was thinking the other day about the infiltration of the panel. One possible good solution would be to get section of SS piano hinge and a small piece of SS sheet metal, and make a lift up panel that would simply lay across the top of the heater and extend out far enough to protect the panel. You couldn't use plastic lest it metal at some point when the top of the heater got to warm.