Wood Fired Heater - Please Kick the Tires

[KJohn]

First, thanks to everyone who takes the time to de-mystify everything that goes into pool building and ownership. It's unbelievably helpful.

I'm scheming to build a 35K gallon pool in Maine, and given the cost and effort, it makes sense to extend the season. Spring and fall shoulders will need some "heavy lifting" heat-wise. There's propane which is convenient but prohibitively expensive, $5-7K per year life-cycle back-of-napkin estimate. From what I've read here, solar and heat pumps work great for maintaining temps but depend on good weather and don't seem well suited for shoulder months.

So I'm looking at a 300K btu wood fired heater. I heat my house with wood, can get firewood at little or no cost, and don't mind the hassle of feeding the stove. The life-cycle cost would be low.

Here's a pic of the heat exchanger:




The headers are 1.5" fabricated Type 316 stainless steel, 1/8" wall. The small pipes are 3/8" Schedule 40 Type 304 stainless, 0.095" wall.

The stove includes a lug for bonding.

I do plan to have a SWG, and have seen titanium heat exchangers supposedly designed for salt pools. Is there likely to be a problem with corrosion (or anything else) with this heater?

Thanks, John

 

[ajw22]

You want 316 or even better 316L stainless steel for pool water. I don't know how well the areas using type 304 stainless will hold up.

@acKsw commented about stainless steel in this thread...

Salt and steel

Hi there, so I am in the process of finalizing our spa design, and have been talking spillovers with our builder. We are going to have a fairly wide, 5-6 ft spillover, which sort of reduces our options to a stone slab, or a copper/steel spillover. Talking with the copper/steel company, I...

www.troublefreepool.com

 

[setsailsoon]

First, thanks to everyone who takes the time to de-mystify everything that goes into pool building and ownership. It's unbelievably helpful.

I'm scheming to build a 35K gallon pool in Maine, and given the cost and effort, it makes sense to extend the season. Spring and fall shoulders will need some "heavy lifting" heat-wise. There's propane which is convenient but prohibitively expensive, $5-7K per year life-cycle back-of-napkin estimate. From what I've read here, solar and heat pumps work great for maintaining temps but depend on good weather and don't seem well suited for shoulder months.

So I'm looking at a 300K btu wood fired heater. I heat my house with wood, can get firewood at little or no cost, and don't mind the hassle of feeding the stove. The life-cycle cost would be low.

Here's a pic of the heat exchanger:


View attachment 177170

The headers are 1.5" fabricated Type 316 stainless steel, 1/8" wall. The small pipes are 3/8" Schedule 40 Type 304 stainless, 0.095" wall.

The stove includes a lug for bonding.

I do plan to have a SWG, and have seen titanium heat exchangers supposedly designed for salt pools. Is there likely to be a problem with corrosion (or anything else) with this heater?

Thanks, John

Titanium isn't needed for salt pool at all. If you balance the pool chemistry salt will not be a problem. Just follow TFP recommendations and you'll be fine.
Chris

 

[KJohn]

Thanks for the replies and link.

I did some more snooping and apparently 304 stainless can get pitting/corrosion with chloride/salt at 100 ppm. 316 stainless has molybdenum, which helps it resist salt up to 2000 ppm. But I couldn't find anything about how each alloy behaved in real life.

Also, pitting apparently happens when the water is still, not when it's moving. So scheduling the vs pump to run a lot, flushing the heat exchanger pipes thoroughly at the end of the season, and keeping the chemistry balanced might do the trick.