If you turn all the stats down, do the upstairs rads get warm ? Don't forget that the actuator heads may take as long as 20 minutes to close the valves - I'm assuming there are thermal actuators on the UFH zone valves.Ah, right thanks.
I've only got 7-way manifolds on the UFH with five individual room thermostats. So, if the room 'stats don't demand heat from the system and if the TMV is faulty, where's all the excess heat going?
Sounds like a flow rate problem then - either a blockage, or more likely an issue with the pump. Perhaps one of the more experienced people would care to suggest what is most likely - are impeller failures common ?Of the 2 pipes coming out of the top of the boiler, one is too hot to touch and the other is hot.
At the UFH manifold, the pipe between the electric valve and stat is warm (boiler flow one?) and the other pipe is pretty cold (loop?)
I think that confirms that it's a lack of flow problem - with the return pipe cold AND a good flow rate, the boiler shouldn't have been able to get the outlet hot all that quickly. Also, the pipes upstairs should have got hot quite quickly - tracking the rise in flow temp from the boiler.Did a cold start with just the upstairs rads. One of the pipes at the top of the boiler went from luke warm to cold very quickly and the other one got very hot quite quickly. The pipes upstairs around the pump and valve got hot within a minute or so of the boiler firing up.
A couple of the rads got hot reasonably quickly but some of them took a long time to get warm and a couple stayed cold.
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