water migration

Al_11

I got a problem,
last fall I installed a Burnham Spirit boiler with a primary/ secondary set up. All was fine with the world until last week when I got the call that the boiler won't stop heating the house. I told the homeowner to shut the boiler off and I would be by this afternoon to check it out.
I start the system up cold and it hums right along, I have the t-stats off in both zones. Primary loop gets to temp (180) and cycles off. I feel the pipes at pumps and they remain cold. I shoot the bull for 20 min. and check again and I can feel the heat migrating through the pump just ever so slightly but it is happening.
I have got check valves on both returns, on the horizontal run to the primary. I have had a problem on other jobs where the water starts to backfeed through the return and the check's prevent this problem.
This is migrating through the pump, first time I have seen this. How can I stop it. HELP!

Steamhead

Are the pumps

located above the primary loop or below it? If they are higher, it might just be gravity flow up and down the same pipe.

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kevin coppinger_4

you could try a couple of IFC ....

circulators..what is you spacing of your tees? kpc

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lchmb

another suggestion

If you find no problem's with the setup, I would consider looking into an underslung thermal trap..This should trap any flow you may have through the loop. I would first verify that the flow check is working and that there are no leak's in the loop itself. Also, out of interest, are your tee's as close together as possible as this will make a difference? good luck...:)