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  • 2-zone HW heat

    Next door neighbor has a 2-zone HW heating system. (baseboard) It has two pumps each controlled by a thermostat. (one for each pump) The burner is controlled by an aquastat. A second neighbor contends that the pumps could run continuously and the stats would still control the heat. (the stat wires go to a relay that closes when the stat calls for heat and activates the pump) I contend there is no way to control the heat if you bypass the relay and make a direct connection to the pump. (for continuous operation) Am I missing something here?

  • #2
    Re: 2-zone HW heat

    You cant bypass the relay because if you have a low voltage thermostat, you need to bridge the low voltage with high voltage, the high voltage will kick in the pump. Bypassing the relay , meaning taking out the relay, you wont be able to activate the pump when needed. Realistically, if the system has been working for years and years, dont touch it until its broken. Chances are making a mod to think the system can be improved might make a mess and you ll end up going back to the first scheme. However, if the pump keeps running, the baseboards will always remain hot. In some cases i would have a continuous pump to keep the bypass water going round and around to keep flow in the boiler but that one would kick in only if calling for heat.

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    • #3
      Re: 2-zone HW heat

      Originally posted by robertochekwong View Post
      You cant bypass the relay because if you have a low voltage thermostat, you need to bridge the low voltage with high voltage, the high voltage will kick in the pump. Bypassing the relay , meaning taking out the relay, you wont be able to activate the pump when needed. Realistically, if the system has been working for years and years, dont touch it until its broken. Chances are making a mod to think the system can be improved might make a mess and you ll end up going back to the first scheme. However, if the pump keeps running, the baseboards will always remain hot. In some cases i would have a continuous pump to keep the bypass water going round and around to keep flow in the boiler but that one would kick in only if calling for heat.
      yea, what he said

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      • #4
        Re: 2-zone HW heat

        Thanks for the replies, guys. I don't want to mess with the system. The second neighbor does. If I read your response correctly, you are agreeing with my contention that if the relay is bypassed, the baseboard would continue to heat and the thermostat would control nothing. (All it controls now is the relay)

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        • #5
          Re: 2-zone HW heat

          I think the second neighbor has seen systems with zone valves on a secondary loop.
          No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

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          • #6
            Re: 2-zone HW heat

            i say let the other neighbor change it and when the house gets to 100* maybe he will say he did it wrong
            Charlie

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