UFH downstairs and radiators upstairs balancing question

Walnut-tree-cottage · 2025-10-31T12:34:55Z

I am running pure WC on .4 curve in our new build with UFH downstairs and Radiators upstairs. This is a single zone with radiators sized as per the design. Whether that design was competent or not is to be determined. Downstairs temperature is measured in the hallway at 23 degrees C ,while the 'desired' is 21.5. i have tried to back off the Hallway circuit. Stat is wired and in the hallway. Does anyone have a proven strategy for getting more heat out of the radiators upstairs while not overheating the downstairs UFH? When i try to look at the flow valves on the manifold to see where the red disc indicators are sitting i find that there is no flow because there is no call for heat for such long periods of time. Perhaps this is an indication that the UFH combining with the level of insulation and airtightness means very little heat is actually needed. Did i explain that well enough?

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davidnolan22

(@davidnolan22)

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Joined: 10 months ago

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04/11/2025 7:43 am

@ashp-bobba

Can I pick you brain about mine

260m2 house.

2 x UFH manifold, one 150m2 manifold in new extension, one 50m2 in old ground floor. 110m2 rad run for bedrooms above.

Ive a LLH, 2 primary circuit pumps, one pump off the header for rads, one shunt pump to the manifolds and one pump on each manifold.

Its now running all open with only one stat, no UFH stat control. The design has not been great and its been a struggle, this is my second winter. The UFH can heat those areas at very low flow temps, rarely above 30 degrees unless its close to zero or below outside.

The temp gap to rooms above can get quite wide, sometimes a bit too wide.

Say my flow/return is 30/25, the DT of the rads is only 1, and the UFH slightly over 5. I’ve spoken to my installer about getting more DT off the rads. The advice has been in increase the speed of water through the UFH, turn all pumps to max. My UFH is a mix mainly 12mm low profile pipes and some 16mm traditional. Putting the pumps to max does nothing unless I also open the flows the UFH loops, but if I do that, parts of the house that only need 20% of the heat loss can consume much of the flow of the primary and get even warmer. Am I best to start to restrict flows into the house that get too much heat. My installer warmed me not to do this the water would be flowing to slowly in that part and the return would be too cold

Any before you ask, no they have not balanced it for me, they have offered to come back at some point.

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