pressurized indoor boiler

[jdurant]

Hey eric (the man),

I got a question for you is it possiable for me to use a closed system to heat a pool? I know that a closed pressurized system can not see air because it will rust out but can I use a water to water heat exchanger to a side arm pool heat exchanger to heat a swimming pool?

 

[Eric Johnson]

Don't confuse enthusiasm for knowledge.

Since a pool is just a big tank of unpressurized water, I suspect you would need a big flat plate heat exchanger for pool heating. But having never seen one, that's just a guess.

With the right heat exchanger, you can heat anything with a pressurized boiler.

 

[webbie]

Special heat exchangers are needed because you don't want the pool water to cross with the boiler water (BIG problems)......and you also need special metals to stand up to chlorine

You need something like this:
http://www.ejbowman.co.uk/products/SwimmingPoolHeatExchangers.htm
cupro nickel or perhaps stainless.

Just make certain it is rated for pool water!

 

[steam man]

Here's a picture of my "work in progress". I have two shell and spiral tube heat exchangers in series. The first is for my solar panels and the second is from my oil boiler with the eventual capability of using a wood boiler. This is all located in my basement located about 80-90 ft from my pool. The pump is a 1hp Hayward. I sized the system for about a 45gpm flow rate. I use a 0010 Taco pump off the oil boiler. The boiler can really get "sucked down" when getting the cold water up at the start of the season. My boiler is large enough but I had to play around with the nozzle size. I can heat my 26,500 gal pool about 1-2 deg/hr with the boiler. The solar panels will eventually take the initial load. It worked so well the pool installer wanted me to "fix" his similar system. I got the stainless steel heat exchangers through www.solarthermal.com. I used a flow proving switch, a high limit aquastat, a flow meter, and a differential controller. I added in a large Hayward cartridge filter in after the fact for additional filtration. This is all separate from my outside pool system.

 

[Bob Rohr]

Nice! If you are using a convential non condensing boiler, be sure you have return protection. a large load like that can really pull down your boiler into condensing mode for extended periods. A variable speed injection pump works great for pulsing heat into that HX and protecting the boiler. 45 GPM on the pool side? What size boiler do you have that HX connected to? can the boiler keep up with the "A' side of the HX at those rates?

hr

 

[steam man]

I use a Vaillant boiler set up for cold start with a SWG power vent. It doesn't hold much water. I had to experiement with different nozzles. A 1.5-1.6 gpm seemed to work fine for pool heating though I cut it back for off season (1.2) to stop short cycling. The boiler can do about 185K net BTU max. It is oversize for my house. It is a little taxing on the boiler when the pool water is below 65 deg but it does heat up pretty well. I have a stack temperature monitor on the power vent and it is no where near condensing temps. When the pool is near temperature it is no problem. My pool holds heat pretty well. The Taco 0010 pump was an educated guess. I probably could have gone slightly smaller here. I did want to use a 3/4 hp Hayward pump with that flow curve for 40 gpm but the 1 hp was free and my flow calculations came out close. The Hayward filter (ebay) install will slow down the flow rate when it gets dirty. I mainly use the boiler to get the pool up to intial temp (80-84deg) and to extend the season. I don't use it too often. At high oil prices I will be getting my wood boiler installed ASAP. Hopefully when the solar panels go up it will do the majority of the heating. I do think a boiler return temperature protection valve would be a good idea. When I get my solar panels in the pool will be my summer heat load.