DEWFPO
New Member
First, I want to apologize for the length of this post.
Background :
Our house had a 5 zone hydronic baseboard heating system that uses 5 thermostats with one main Taco circulator pump and one boiler. (a 14 year old Weil-McLain CGa-7-PIDN)
We recently did a remodel and added a 6th zone that is hydronic underfloor heat. The PEX was installed under the subfloor and foil backed insulation was added between the rafters about 3 inches below the PEX.
They installed a separate, smaller Taco circulator pump for the hydronic floor zone(6) only. We added a Taco switching relay to control the circulator pump for Zone 6. The switching relay communicates to the TT wires on the 14 year old Weil-McLain CGa-7-PIDN boiler so that the boiler knows one of the zones is calling for heat and will cycle the gas valve as needed to maintain supply water temp.
The issue I have is :
When zone 6 calls for heat, the circulator pump for Zone 6 comes on and the boiler fires up if needed to maintain temp AND the main circulator pump energizes as well even if none of the 5 other baseboard heat zones calls for heat.
I am concerned that this will wear out the main circulator pump since Zone 6 runs for many hours on end since it is a below floor system.
The boiler only knows that a thermostat is calling for heat and doesn't know that the main pump is not needed for Zone 6. It has no way of knowing.
I can install another switching relay in the circuit that goes to the main circulator pump and wire it such that the main pump only comes on when 1 or more of the baseboard zones comes on, and does not run the main pump if only zone 6 is calling for heat.
My question is : Should the main circulator pump run at the same time as the Zone 6 floor circulator pump when ONLY Zone 6 is calling for heat?
The way Hydronic Floor Zone 6 is plumbed right now is that 1) Hot supply comes directly from the boiler to the mixing valve (which I have set so that the new pump is seeing 120F input supply water), 2) the return leg goes to the cold side of the mixing valve, 3) the blended supply water goes to the new pump, 4) there is a bypass plumbed into the return leg back to the cold (input) side of the boiler BEFORE the mixing valve. (This allows whatever return water that is not reused by the mixing valve to return to the boiler to be reheated.)
Your thoughts are appreciated., DEWFPO
Background :
Our house had a 5 zone hydronic baseboard heating system that uses 5 thermostats with one main Taco circulator pump and one boiler. (a 14 year old Weil-McLain CGa-7-PIDN)
We recently did a remodel and added a 6th zone that is hydronic underfloor heat. The PEX was installed under the subfloor and foil backed insulation was added between the rafters about 3 inches below the PEX.
They installed a separate, smaller Taco circulator pump for the hydronic floor zone(6) only. We added a Taco switching relay to control the circulator pump for Zone 6. The switching relay communicates to the TT wires on the 14 year old Weil-McLain CGa-7-PIDN boiler so that the boiler knows one of the zones is calling for heat and will cycle the gas valve as needed to maintain supply water temp.
The issue I have is :
When zone 6 calls for heat, the circulator pump for Zone 6 comes on and the boiler fires up if needed to maintain temp AND the main circulator pump energizes as well even if none of the 5 other baseboard heat zones calls for heat.
I am concerned that this will wear out the main circulator pump since Zone 6 runs for many hours on end since it is a below floor system.
The boiler only knows that a thermostat is calling for heat and doesn't know that the main pump is not needed for Zone 6. It has no way of knowing.
I can install another switching relay in the circuit that goes to the main circulator pump and wire it such that the main pump only comes on when 1 or more of the baseboard zones comes on, and does not run the main pump if only zone 6 is calling for heat.
My question is : Should the main circulator pump run at the same time as the Zone 6 floor circulator pump when ONLY Zone 6 is calling for heat?
The way Hydronic Floor Zone 6 is plumbed right now is that 1) Hot supply comes directly from the boiler to the mixing valve (which I have set so that the new pump is seeing 120F input supply water), 2) the return leg goes to the cold side of the mixing valve, 3) the blended supply water goes to the new pump, 4) there is a bypass plumbed into the return leg back to the cold (input) side of the boiler BEFORE the mixing valve. (This allows whatever return water that is not reused by the mixing valve to return to the boiler to be reheated.)
Your thoughts are appreciated., DEWFPO