I am trying to research the common methods on an underfloor heating system that are available in the market. I know there are usually,

  • On/Off control to control the flow of water into the pipe
  • Outdoor reset control to control the supply water temperature.

I think the most common is ON/OFF control (simple PI controller), but not sure about it.

  • $\begingroup$ Temperature sensor to control pump and / or valves per circuit $\endgroup$
    – Solar Mike
    Sep 20, 2018 at 10:38
  • $\begingroup$ Yes, the temperature sensor is the feedback. It is not the controlled variable in the system. What I am looking for is do they control the water flow or the supply temperature? $\endgroup$ Sep 20, 2018 at 14:15
  • 2
    $\begingroup$ Your question in your comment is different to what you asked originally. I have designed and installed U/F heating so I had two T sensors: one to cut the pump in case of overtemp, the other to control each room area. $\endgroup$
    – Solar Mike
    Sep 20, 2018 at 15:13
  • $\begingroup$ @SolarMike I've never seen a system where the pump is controled to regulate heat, it would be cool if you could elaborate in an answer. $\endgroup$
    – mart
    Sep 21, 2018 at 8:04
  • 1
    $\begingroup$ @mart if the fluid going into the pipes gets too hot they can get damaged, so a T sensor can stop the pump directly if the fluid gets above a set temperature (I set it to 35 deg C as we built a super insulated home and had the floor running about 24 deg C). The more simple and direct a safety system is, the more effective it is.... $\endgroup$
    – Solar Mike
    Sep 21, 2018 at 16:52

1 Answer 1


The typical appraoch I see in heating systems is to have a three way valve on the suction side of the heating pump. This mixes cool return into the flow into the heater. The controling varialbe is the flow temeprature, the controlled varaiable the setting of the valve.

enter image description here

You then adjust the target flow temperature based on the room temperature you want. Check if such a system works with your heating in terms of hydraulics, I assume a normal heating manifold with hydraulic compensator.

However this is from large heating systems and may be overblown for a domestic purpose.

  • 1
    $\begingroup$ Three-way value is not the way in the usual underfloor heating systems. Usually, the underfloor heating solutions are a multizone system. Yo want to heat multiple rooms separately. So have to use a manifold. Check out this example (underfloorheatingsystems.co.uk/wp-content/uploads/2017/02/…). Now we will need a separate 3-way valve for each zone, so a lot of extra equipment and a lot of extra control. $\endgroup$ Sep 21, 2018 at 8:13
  • $\begingroup$ No way around a separate control for each room unless you accept the same flow temperature in each room. However you can have one manifold supplied by the pump (pump is set to provide constant head), each floor gets one valve controlled for room temperature. At this point I'm pretty unsure what your question. $\endgroup$
    – mart
    Sep 21, 2018 at 9:29
  • $\begingroup$ My question is just to have an idea what are the control methods available in the market for controlling underfloor heating system. Literature study usually tells me the above two control methods I mention, but all these paper are published in the 1990's - early 2000's. $\endgroup$ Sep 21, 2018 at 12:10

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