Underfloor heating cycling question

[trailro]

Hi all,

I have an Evohome set-up for more than a year now and I am starting to notice some odd behavior with the underfloor heating.

The set-up is quite simple: Daikin Gas Boiler with Opentherm. Evohome with UFH and Fan Coils. UFH is all for the ground floor, which also has some Fan Coils to supplement the heating (my assumption is that this is where the issues come from). First floor is all Fan Coils.

Everything 'seems' to be working correctly - especially first floor where the fan coils do their job. On the ground floor, the temperature is fine, but the fan coils fire way too often, and the UFH seems to be all for nothing. I have all the set-up monitored by Home Assistant and what i notice (and also seen it myself) is that UFH would turn on for like 7 minutes, then off for another 6 minutes, then on again for 7 minutes and so on. This results in the floor being literally cold (although I'm sure there is some heat generated). Unfortunately, the same floor being an open space have 1 thermostat for the UFH and another thermostat for the fan coils (both sitting sort of close one to another).

I currently have one zone with all of the UFH manifolds set as "Underfloor heating", and another zone with the Fan coils in the open space set as "Living room".

I tried setting the temperature of the UFH 1 degree higher than the other thermostat for the fan coils to "force it" to run. It does cycle less, prolly 10 minutes on with 6 off, but it's still not good enough. Moreover, when I do this, the water temperature in the boiler goes up, therefore the fan coils give even more heat and they cycle more.

Is it an issue with the way I have configured the system (maybe my error)? or does this seem as normal behavior and somehow because of two heat output solutions (UFH and Fan Coils) sitting in the same open space, the Evohome gets 'confused'? Would it help if I completely remove the UFH controller and I just put a relay that controls the UFH pump and keep the thermostat, that way I remove the need for actuators in this set-up?

Any suggestions greatly appreciated.

Thanks.

[Richard]

So you have 2 heating strategies in the same zone and expect normal behaviour? Its not going to happen.

UFH is slow warm up and fan coils are fast reacting. You cannot have the two heating technologies in one zone, it won't work.