A question for those who know more about UFH control than me…! Our ASHP system (Vaillant Arotherm+ 7kW) is rads everywhere except our large living/kitchen/dining area which will have UFH. Rads are not zoned and TRVs will be set to cap excessive temp so the system is as ‘open’ as possible all the ti…

Ordinarily UFH systems have a pump on the manifold, or it can be remote from the manifold, and a thermal actuator on each UFH loop. Each room then has a thermostat that controls the thermal actuator for the loops in that room. The control box for the thermal actuators also controls the pump / boil…

Thanks for the reply Bob, that’s really useful general info. Note that the UFH manifold has no pump or mixer on the manifold itself as it’s a low temp system (45C max). It’s a https://www.jk-gb.com ‘JK-LT’ manifold. It will rely on the main system pump. So I agree I do need some kind of control ele…

45°C for UFH is pretty hot (mine runs at 30°C and I’m hoping to use a Shelly TRV to bring that down). It is running in a thicker than usual concrete slab for greater thermal mass though. My manifold has a TRV that mixes the incoming flow and the water in the pipes to maintain that flow temperature.…

Hi Brian thanks for the reply. The way the system works is grooves are cut into the existing screed then levelling compound and tiles on top. So the pipes are fairly close to the surface and therefore fast reacting. I will give JK a call and discuss but as you say perhaps 45C is a bit high (the sy…

Hi James, I am a professional heating engineer holding national qualifications in UFH, ASHP’s, GSHP’s and solar as well as being Gas Safe Registered. So, I do know more than a little about heating systems. The system Brian describes is much more typical of most common UFH systems. As you mention…

[image] James314: I will give JK a call and discuss but as you say perhaps 45C is a bit high (the system is designed for 40C max but it would be foolish not to provision for slightly higher in case our heat loss calcs are a bit off). My concern is that it will actually be uncomfortable. Your …

Thanks for all the replies. I’ve also managed to do a bit more research myself now. Note that the system will be using weather compensation - so flow temp is adjusted depending on outside temp. It’s designed for 40C max flow temp at -3C outside temp (but worth making sure we have a bit of margin to…

[image] James314: I’ve also managed to do a bit more research myself now. Always the best way :wink: [image] James314: It’ll be a few months before this is all fitted and up and running but the system will be heavily instrumented One other thought, fit lots of ‘pockets’ in your pipewo…

“fit lots of ‘pockets’ in your pipework for temperature sensors” Good thought, though having played about with our old system using temp probes with a bit of thermal compound on copper pipe and insulating over the top works well too. “wish I’d fitted a flow meter on my DHW so I know when HW is be…

[image] James314: Good thought, though having played about with our old system using temp probes with a bit of thermal compound on copper pipe and insulating over the top works well too. That is what I have, but I still wish I’d fitted pockets. [image] James314: If you don’t need to know…

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UFH control for heatpump system

Hardware Heatpump

Robert.Wall (Robert Wall) 19 June 2026 18:02 21

See UFH design.