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hydronic radiant floor relay solution for solar assist
<span>I think I finally figured out how to wire my solar pump (P1 on attached diagram) feeding my hydronic radiant floors & hot tub, which is fed by a home-built solar tank (450 gallons), and a mod/con boiler (TriangleTube). If you have experience with such things, please review & let me know if I’m in the right path, or if there is a better way. My three zones are upstairs (five 300 foot loops), downstairs (four 300 foot loops), and the hot tub heat exchanger. The call for heat from the hot tub aquastat or either thermostat goes to a Taco SR503-4 three zone switching relay. This 1) opens the appropriate zone valves, 2) operates the boiler, and 3) powers the Grundfos Alpha (P3) that automatically ramps up or down when zone valves open& close. The Taco Switching Relay comes with good instructions & seems easy to wire. My issue is to properly power P1, which adds BTUs to the returning water if available in the solar tank. Since this solar heat is cheaper, it is introduced into the loop before the boiler’s gas-heated water. The logic to control P1 needs to be that there is a call for heat AND the returning water temp needs to be less than the solar tank water temp. Otherwise, the tank would be cooling the water instead of adding heat to it. I believe the answer is two relays wired in a series & a Delta-T controller. The hot wire to the P1 only makes a circuit when both the ‘call to heat’ relay is powered AND the Delta-T relay is powered. I plan to use two Omron </span><span>LY2N AC110/120 relays (normally open). Is there a better way to do this, such as a delta-T controller out there that contains relay control already in it?</span>