Add A Propane Heater?

[GregJ52]

I have a very small pool/spa. It is roughly 7x17 and 54" deep.... approximately 3,500 gallons. We live in the Pacific Northwest. We have a Hayward heat pump that heats our pool very nicely until November and then starts working again in March. We keep the pool/spa very warm.... like 92 to 96 degrees..... We get into our pool to warm up We are starting to look at a propane heater to cover the colder months. I have a couple of questions. First, would it be safe to plumb the propane heater in line with the heat pump? If so, in what sequence? I would assume heat pump first and then propane heater because of the higher heat of the propane. The next question would be... Can anyone recommend a good, small heater for a small pool/spa like this? How reliable are they and what is the average life span? I am just starting this research and you know what they say.... "The more you know, the more you know what you don't know...."

Thanks for any help on this,
Greg

 

[ps0303]

Yes it is safe and done often. Have the heat pump first and then feed it to the propane unit. Raypak makes probably the best heater to date. I would look at getting their 266K BTU unit unless you really want a very fast heat up and in that case get the 400K BTU unit.

 

[danpik]

Paul pretty much covered the brand.

At 3500 gallons, the pool has about 30,000 lbs of water in it. since most heaters run in the 80% efficiency range, anything over 100,000 BTU will work fine. At 100,000 BTU, you will see just under 3 deg/hr of temp rise and at 250,000 BTU you will see about 6-7 Deg of temp rise/hr. This of course is under ideal conditions. Colder air temps, solar covers, etc will also affect the temp rise as well.

As far as the life span of heaters, it depends on how well you take care of them, the environment they are exposed to, water chemistry, etc. my little Hayward H100 has lasted me almost 12 years now with two minor (to me) repairs. One was a self inflicted problem due to water chemistry (until I found this site) and the other was a problem Hayward created and will not acknowledge as a problem. I was able to repair both, ironically, with the same roll of solder.

Dan