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I have an older house with single line hydronic heat & baseboard radiators, no A/C except for a mobile unit we put in the upstairs bedroom.
I'm thinking of plumbing a heat exchanger into the main circuit in the basement using the main water supply for the cooling side, so any fresh water you use in he house anyways will contribute to cooling for just the one time installation cost & the electricity to keep the pump running through the off season.
Has anyone here attempted such a thing, would there be a noticeable or only a barely measurable result?