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No flow to some loops?

I purchased a house with radiant floor throughout. Some in slab, the rest stapled up to subfloor.

I have a couple of rooms that don't appear to get heat, one seems to get essentially none, the other gets some but not enough.

The room that gets no heat is on the first floor (not slab), the other that gets some heat is on the second floor. I have identified manifolds that I believe service these two rooms, both have loops with flow valves that don'
t show much flow, and i cant twist the flow meter to get any more flow.

Pictures from the manifold that I believe provides for the 2nd floor insufficient heat room.

I tried purging the system, i never saw any gurgling in the bucket, and the situation didn't change.

Do I need new flow meters, or a new manifold, or is this potentially a problem elsewhere in the system?

Unfortunately the system was installed 15 years ago and the house went through a couple foreclosures, so I have not contact back to the original installer.

Any help is greatly appreciated, the two affected rooms are my office and my bedroom, so I spend my most time in the coldest rooms. Thanks.


  • Zman
    Zman Member Posts: 7,472
    How is the tubing installed? With transfer plates or just tubing stapled up?

    Your flow rates don't look bad, what are the supply and return temps like? You don't need to be very scientific, just cold, warm, hot, too hot to touch...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • nesnahojk
    nesnahojk Member Posts: 2
    The supply is hot, I can touch it for like 3 seconds before its too hot to hold. The return is warm, but I can hold it and never feel too hot.

    Just noticed that the one loop with the lowest pressure has a small leak coming out of the flow meter.

    The other manifold that I think would affect the first floor room, has three loops with the low pressure.

    All the ceilings are finished so I can't see the tubing, but I did have to replace a small piece of water rotted subfloor awhile go and it didn't look like there were any plates.
  • Gordy
    Gordy Member Posts: 9,537
    Sounds like a heat transfer issue. If the tubing is hot at supply, and warm on the return you are getting flow as indicated by the flow meters.

    If it is a true staple up there is no plates, unless it’s speculation in your part.

    You do have a scenario where the different types of radiant panels require different water temps.

    The lowest would be the slab, and highest staple up.

    What are the floor coverings in the problem areas? High r floor coverings will reduce output.

    My opinion right now is determining what water temp the staple up is getting, and what temp the slab is getting needs to be confirmed. Also if you can confirm if plates, or no plates were used.