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radiant overheat

Joe_10 Member Posts: 22
with radiant and hbb on same loop.Originally designed to have seperate temp loops for each hbb at 180 and radiant @ 140. When the system was built they used only one loop for both set at 140. Have had rooms at the very end never warmed up even though outdoor temps have been mild for last 8 yrs. the age of the home. The current problem is overheating in some radiant rooms. Three of the farthest zones from boilers have a combined radiant and hbb on same loop. I have got the temps up in those rooms by boosting water temp to 150 but now have radiant floor rooms with t-stats set at 55 getting to 75+ degrees. Most valve are wirsbo telestats none original all have been replaced two "new" telestats failed and were replaced and corrected overheat in one room but other is still hot. To complicate matters is that the system is solar assisted.Which when it kicks in it cuts out the boilers but has been set at less than 120 degrees.Boilers are weilmclain gold piped in parrallel one boiler set at 140 the other at 130. I have tried switching zones and determined that I make things worse that way.So I am relatively sure that t-stats are connected to correct loops. I can access the supply and return manifolds if needed I just want to make sure that I am working in the right direction and that there is not some other problem that I am over looking.I have been thinking that there needs to be injection heat to the floors with radiant however that leaves the combination floors and hbb.
Thank You for your time in advance.


  • Art Pittaway
    Art Pittaway Member Posts: 230
    First things first.

    You can't compromise the water temp and make it work. It needs to be separate temps and controls for the radiant rooms and the baseboard. These two systems work totally different and will just fight each other. From your post it sounds like you were called to fix this, and now the customer wants you to wave your wand and make it better. Somebody did a half-donkey job and split with the cash. Up front, you should figure the systems need to be separated, and proper controls installed. Boilers need to be set up on primary/secondary loop with some type of mixing down for the radiant. This will take your time because you need to redesign it so it works together. If the customer is not willing or financially able to undertake this, think long and carefully about how much YOU want to spend.
    Best wishes, Art
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