Swimming pool solar heating system

When we bought our current house quite some years ago, it had a reasonable size “in ground” swimming pool that was suffering a bit from lack of maintenance.  The re-made ground around the pool had settled over the years and many of the paving slabs laid on it had cracked, one of the skimmers had twisted and cracked for the same reason and leaked water from the pool, the pump bearings were shot and the heating system (which involved pumping the pool water through thirty-odd lengths of black hose mounted on a barn roof) didn’t work at all well.  The pool liner was also in need of replacement.

Some would question the sanity of an outdoor pool in the UK and I’d not necessarily disagree with them, but since it’s there we used it for a while until the pump had really had enough and then I decided to set about returning the pool to a decent state.  The first job was to replace the liner and put in a new skimmer to replace the cracked one.  It wasn’t until the liner was removed that I discovered the rendered inner face of the pool structure had also broken up in places and without the weight of the water was actually leaking groundwater into the pool.  Fixing that took some time as I ended up having to chop out lots of the collapsed rubble, build up the structure with concrete and then render over the top again, all whilst water was still trying to get in.  I put in some field drains around the outside of the pool which helped to control the water a little, but it didn’t entirely stop it. Here’s how it looked when I started:


And after I’d made good the broken area:


And with the new liner:


That done I replaced the pump and then set about re-laying all of the slabs, making up the ground underneath properly and replacing the broken ones.  Having done a few other bits of maintenance the pool has actually seen a fair bit of use unheated this summer, but only because it’s been warm enough to heat the water in the pool directly.

The next stage is to build some more effective heating system for the pool water. Originally the pool water could be pumped through about thirty black pipes on the roof of a barn to heat the water, but the system leaked and never worked to my satisfaction. One of the major problems in replacing it however is that chlorinated water isn’t good to mix with copper pipework, so I’d have to do everything in ABS or stainless steel (the latter being far too expensive and too hard to work with).

Finally I decided to build a heat-exchange system, allowing me to keep the pool water in plastic pipe and use copper for the rest. The idea is to have an in-ground (for insulation) reservoir of water that is heated using flat-plate solar panels that I shall build myself. Water from the pool will then be run through that reservoir in small diameter pipes, being heated as it goes. The reservoir itself will be made of a concrete base with concrete block walls, waterproofed and insulated on all sides.

I’ve now completed the first stage — building the reservoir and space for the pumps:



The larger section, about 1.2m by 0.9m by 4m will be waterproofed and insulated before being filled with water. The smaller section will hold the pumps. Fitting the waterproofing and insulation will be the next step.

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