Controlling radiators and UFH

[Drew1000]

I’m am installing ufh and rads in new build. UFH is straightforward as each room has its own programmable thermostats. Upstairs will be radiators but was wondering what the standard is for switching off the boiler once all Trvs  had reached temperature. Do I need to keep one rad or towel rail free from trv ie bypass and should I fit a thermostat which switches boiler off perhaps in up stairs hall   Any advice much appreciated

[joth]

The standard is as you say: one radiator somewhere central without trv and has a room stat.

The alternative is using smart TRVs on each rad that includes the connection back to "call for heat" when they are open.  Honeywell evohome, tado, hive,, etc. These have benefits of being able to centrally (and remotely) setup which rooms are warm when, but of course at a cost of complexity. 

What system are you using for the ufh room stats?

Edited July 23, 2020 by joth

[Nickfromwales]

On 22/07/2020 at 22:50, Drew1000 said:

I’m am installing ufh and rads in new build. UFH is straightforward as each room has its own programmable thermostats. Upstairs will be radiators but was wondering what the standard is for switching off the boiler once all Trvs  had reached temperature. Do I need to keep one rad or towel rail free from trv ie bypass and should I fit a thermostat which switches boiler off perhaps in up stairs hall   Any advice much appreciated

The issue will be short-cycling the boiler, which is likely to happen when the UFH is the only thing calling for heat and it's up to temp, or close to it.

Each zone of heating ( upstairs - rads / downstairs - UFH (?)) needs its own time-clock at least, for basic heating on or off, and then thermostatic control is applied as required. Upstairs heating would be best off on a time-clock IMO as a 1st floor thermostat would e very poor reference for what is going on in individual rooms, especially if the doors to them are closed.

If you install TRV's, it is in the boilers MI's that you provision a bypass, but if the two heating zones are isolated by 2-port zone valves then you need an automatic bypass before them also.

If possible I would configure the system to have the UFH and towel rad(s) on the same flow and return loops ( all the UFH can still shut off heat to spaces via the dedicated room stats ) so the towel rads can help alleviate the short-cycling issue. Those towel rads would need to have lockshield valves so they cannot be turned off inadvertently.

I would have a time-clock for upstairs but no thermostat, and stay as you already intend to for the UFH.  

[Drew1000]

Thanks for advice guys, sounds like a time clock is a good idea.  I am installing a NU Heat system downstairs with programmable digital thermostats for each room.

[PeterW]

7 minutes ago, Drew1000 said:

 

Thanks for advice guys, sounds like a time clock is a good idea.  I am installing a NU Heat system downstairs with programmable digital thermostats for each room.

 

why...???!!

 

Price the same stuff up from Wunda and I’ll split the savings with you..! 
 

There is no point on using stats per room - heat will transfer between each room even when the doors are open and the heating is off in the other rooms you will get zero benefit from £500 of digital stats. 

[Drew1000]

Peter,  Each room partition is well insulated (internal partitions) so would not expect too much heat transfer between rooms.