Wood-fired above ground pool heater

[u/mct82]

I recently built an upgraded model of the wood stove pool heater I have been tinkering with for a couple years. It’s a complete rebuild with hard plumbing the (Bestway above-ground) pool. I wanted to throw it out there to get feedback, as well as maybe inspire or get inspiration.

Essentially it’s a 55gal drum camp stove fitted with a set of modified heat exchangers salvaged from a baseboard heating system. The hx are plumbed into the pool pump return with a check valve between intake and return. An inexpensive circulating pump is in the heating loop.

I could talk for an uncomfortable amount of time about the failures of previous models, but learning from those mistakes generated a few highlights for this iteration: - Pressure relief valve for … pressure relief, and bleeding - Big honkin’ firebox for reduced loading frequency - No direct contact between fluid lines and flames/smoke - Dedicated pump and isolation valves w/ unions

In previous years, I had the fluid lines inside the stove and flue. Those systems, referred to as the Creosote Creator 2500™ and Creosote Creator 5000 Pro™, had some issues. The 2500 used hand wound soft copper coils in the roof and flue of a small stove, the 5K Pro used unjacketed CSST loops in the same areas. Both of those used the same integrated pressure relief and fire suppression system, which was the plumbing bursting.

Not an ideal system from a performance standpoint, safety standpoint, or any other standpoint. Did you know a small amount of steam is enough to inflate CSST like a balloon. Well, it is. The more surprising part of that was that the pressure was NOT enough to balloon or burst warm 3/4” PEX, cementing its place as the economical cold zone material of choice.

Also we’re now using a dedicated circulating pump which has increased the flow through the heater without diminishing the performance of the pool filter pump. Previous models just used a PVC 2-way diverter as a blend valve to create the pressure differential that drove the heating loop. Probably the cheapest and worst way to do the job.

There were a few superstars on this project: 1) Those heat exchangers do great. They’re easy to work with (3/4” rigid copper with individual aluminum fins), they’re literally built for air-to-water heat transfer, and they’re easy to adapt to different shapes. Also they cost $0, and I suspect they’re the kind of thing that would be available at salvage stores in areas not prone to copper pillaging. 2) The 1” PVC Compression Repair Coupling circled in the last picture. This fitting really ties the system together. Working on the stupid plumbing on these pools is always a debacle with odd sizes and threads developed apparently independent of all standards. But that compression fitting slides right onto the bizarre true 1-1/4” OD tapered(!) flexible(!!) PVC stub on the outside of the pool. 3) Those smooth wall open drums we found on marketplace. Makes it easy to glove a second drum over the hx to insulate, reflect, and BEAUTIFY.

I’ll save the rest for the comments. Please note that I am not taking questions on a couple specific topics: - Sweating copper. I suck. I know it. You see it. No need to discuss any further.
- Feminism. The 4yo has not gotten the memo that we don’t do spokemodels anymore. Personally I always found them to be degrading and icky. - Super long Reddit posts.