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Forums > Green Building Technologies > Radiant Heating > Subject: Radiant heating help (garage)

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76harleyUser is Offline
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Posts:1
02/01/2006 6:16 PM  
I have radiant heat throughout my entire home- We just fired everything up, and all is working fine except the lines running out to garage. Our boiler and all pumps are setup in the basement, including the pump for the garage. Here's the situation- we have a grundfos 26-64 pump running the garage. There is about 90 feet of 1" PEX for both the supply and return lines from the basement. The supply line runs vertically for about 11'-12' runs through ceiling of garage, then drops back down approx. 11'-12'to the garage floor manifold and the return line runs vertically for 11'-12' up to and through the garage ceiling, then back down again 11-12' to the mech. room in the basement.

We are not getting much flow to the garage if any- the heatloss calls for 3.2gpm feeding the garage, and I was told the Grundfos pump was a high head pump. I have a mixing valve before the pump, and a temp gauge right after the pump. I also have a temp gauge in the manifold in the garage. The temp at the pump is 105, and it seems to slowly drop from 105 until I open the valve to release pressure on the return manifold. Then the temp. climbs back up. The system is set at 12# of pressure. Would increasing the pressure overcome the rise in the piping, or do I need another pump in the garage to push the water back to the boiler? or any other suggestions?
UnregisteredUser is Offline
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Posts:2321
02/02/2006 11:54 AM  
Suspect you need an air removal vent at the highest point. The orientation of the pump may also contribute to air concentrating at the suction Should be vertical discharge up - so air moves to the vent positioned on a vertical branch above the highest point or as high as you can get it. I had similar problems with a one loop pump even without the mixing valve complications . I also installed a full size dump valve on the return to "rush" the air out - assisted by the supply pressure - do this with the pump running & see if the pump runs slightly quiter after . This proves air not collected at suction. Higher pressure will shrink the air to assist in pushing it through but new air is likely to build a bubble again. Definitely no need for second pump!
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Forums > Green Building Technologies > Radiant Heating > Radiant heating help (garage)


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