Get buckets of water from your pool (or lake or well) and put them in the fridge till they cool down. Then dump the water outside and get a new bucketful). To save effort you could run 2 hoses with a small pump. You are now heating your house with a ground source heat pump.

I really enjoyed reading The Homemade Heatpump Manifesto on Ecorenovator. https://ecorenovator.org/forum/showthread.php?t=484