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UFH downstairs and radiators upstairs balancing question

 
Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by JamesPa 5 hours ago
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 Walnut-tree-cottage
(@walnut-tree-cottage)
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Joined: 5 days ago
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Topic starter 31/10/2025 12:34 pm  

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?


This topic was modified 7 hours ago by Mars

   
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 JamesPa
(@jamespa)
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Joined: 3 years ago
Posts: 3263
31/10/2025 3:36 pm  

Posted by: @walnut-tree-cottage
↑

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?

Have you tried turning up the stat and turning down the flow rate to the UFH.  If the stat is acting as a call for heat (which it sounds like it it) this will ensure that the heat pump is running continuously rather than being turned on/off, thus delivering heat to the rads rather than starving the rads of heat.  By turning the UFH flow down you restrict the amount of heat to the UFH, without simultaneously restricting the heat to the rads.  Its essentially balancing.  You may need to adjust the WC curve down.

Ideally you should get to a point where all stats and TRVs (or at least most of them) are set well above (at least 2C, but start off with setting them to max) the desired temperature, the flows are adjusted so that the relative room temperatures are correct, and the WC adjusted to the minimum level possible consistent with just heating the house.  This is basically how an ASHP should be operated for max comfort and efficiency.  It would be worth your while reading this guide.

 

Have you got a buffer/LLH between heat pump and emitters?  How many water pumps are there?

 


This post was modified 5 hours ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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