Radiant Pump pumping main zone too?

Jim_46

I have a sneaky suspicion that my small pump that is supposed to be pumping only for the radiant floor is also dragging water through the main system too and that is why the little pump is over heating. I've had it running for a couple of hrs now and the rest of the house and rads are staying hot even though the main zone radiator circulator isn't kicking in nor is the main thermostat calling for heat. If you look at where I teed into the main hot water to go to the new zone you'll see that I have no check valves there so the hot water from the boiler can go in either direction. The new pump is 17' away from the boiler and does have a check valve after the pump but back at the boiler the main zone is going off to the right with no check valve so it is possible that the new pump is also pulling the main zone through too. What do you think? Should there be checks here at the boiler for both directions?

Al Letellier

ghost flow

Can't tell much from the photos, but in a forced hot water system, you need a check valve (flow check) for each zone. Without them, you get flow everywhere. Each circulator should have it's own flow check.

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Bill Nye_2

If You're

Still using that steel expansion tank, that new air vent isn't going to help matters.

The hot boiler water will flow by gravity through your main zone. If you used a thermostatic mixing valve, the pump needs to be on the radiant loop side of the valve. If you have it on the supply from the boiler the valve will close against the flow because of the temperature of the water. That is what the valve is made to do.

Did you get all of the air purged out the new zone?

hr

Bullheading like

that can offer funky results. Looks like you are pulling flow two different directions from the branch of the tee?

Me thinks you need some repiping on this job, with the correct components in better relationship to one another.

hot rod

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Mellow_2