Quote Originally Posted by kevinsmart View Post
It took a while (largely due to lack of support for this in the UK) but I now have the HM80 controlled solution for my single-zone UFH in place. And it works great, I no longer see the 1 degree overshoot, the set temperature is reached and maintained within around 0.1 degrees over several hours.

It's entertaining watching the controller make quiet regular small adjustments to the rotary valve to maintain temperature.

One interesting observation was this freezing morning with a 15C setback temperature and 15.5C measured temperature, the controller decided to run the pump, with Evohome indicating a 0% heating demand (but other zones heating). This appeared to stop further heat loss in the zone.
@kevinsmart I realise this is an old thread. But I am wondering if you can shed some light. I too have a mixed system of rads and one large UFH zone. The UFH zone is currently feed using a separate normally closed motorised zone valve. So I have a fairly simple system I.e. BDR91 opens the zone valve, the micro switch in the zone valve operates the UFH pump. My UFH manifold has a manual TRV set to 35C. All the manifold outlets are always open i.e. I am not using electric actuators on each circuit.
So what needs to change, if I move from this to a HM80?