Weather Compensation on Both Rads and UFH?

[Dam4n]

I've got Vaillant weather comp on an oversized 637 boiler. The low flow on rads works really well using the vaillant controls, but the UFH is still on on/off controls via the heatmiser. I think the UFH would benefit from vaillant controls an constant flow temp rather than on/off as it currently is. Do you have any thoughts about this? Thanks

 

[rhinoman]

I had Heatmiser on my UFH and ditched it when I fitted Vaillant WC, much better and more efficient just using slight setback.

 

[ScottishGasMan]

Id say the same. You don't need individual room controls anywhere near as much when using weather comp vs high temp heating.

Only downside, is that if the rads need to run at higher temperature than the UFH then the boiler will have to supply the higher of the two flow temperatures, youll still have an underfloor mixing valve to blend the temperature down, but if its of a manual type then it will mean it over heats the floor most of the year as they will be set to blend to the temperature required at design day (coldest day)

That can be circumvented by using an electronic mixing valve which some vaillant controls (VR70/VR71) can control, so they can fully alter the flow tempearture to the UFH circuit based on the weather comp, even if the rads need a higher temp

 

[Sucker69]

Id say the same. You don't need individual room controls anywhere near as much when using weather comp vs high temp heating.

Only downside, is that if the rads need to run at higher temperature than the UFH then the boiler will have to supply the higher of the two flow temperatures, youll still have an underfloor mixing valve to blend the temperature down, but if its of a manual type then it will mean it over heats the floor most of the year as they will be set to blend to the temperature required at design day (coldest day)

That can be circumvented by using an electronic mixing valve which some vaillant controls (VR70/VR71) can control, so they can fully alter the flow tempearture to the UFH circuit based on the weather comp, even if the rads need a higher temp

I am trying to understand your message. Would it be possible to remove motorised valves, vr71 wiring centre and room thermostats?
The Vaillant Ecotec plus with vrc 720 and weather compensator would be sufficient to run all radiators and ufh in one continuous loop.

 

[ScottishGasMan]

Yes, generally this would be the best way to run it. Don't bin the motorised valves and room stats straight away, but could certainly disconnect them and see how it all runs, if it needs a little tweaking with the heat curve and balancing system then that would be done, if your happy enough then remove them, if not you can always plug the additional stats back in.

 

[Sucker69]

Yes, generally this would be the best way to run it. Don't bin the motorised valves and room stats straight away, but could certainly disconnect them and see how it all runs, if it needs a little tweaking with the heat curve and balancing system then that would be done, if your happy enough then remove them, if not you can always plug the additional stats back in.

If we remove motorised valves, room thermostats, and vr71 wiring centre….How can we link/wire Vaillant Ecotec plus boiler to unvented cylinder and ufh?

 

[Sucker69]

Yes, generally this would be the best way to run it. Don't bin the motorised valves and room stats straight away, but could certainly disconnect them and see how it all runs, if it needs a little tweaking with the heat curve and balancing system then that would be done, if your happy enough then remove them, if not you can always plug the additional stats back in.

I have bought the VRC720 and VR71.
I just wanted to clarify when wiring in R1 and R2, normally I would connect the motorised valves for downstairs and upstairs. If I don’t make connection, how will the Vaillant boiler know when to fire up?
I believe that I need to configure the vrc720 to create a heating circuit and base it on a weather curve…
Do you have clear instructions as to how I can configure a continuous loop?