Weather Compensator - Vaillant VRC 430 setup

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I've had a VRC 430 for a number of years but only really just getting round to configuring it correctly now that the missus is nagging me about the cold upstairs and the kids waking up in the night

Currently its mounted into the wall in the living room and set to Thermostat mode with a curve of 2.5 - the scheduler is set for 20oC from 06:30 - 7:30 (morning) and 22oC between 16:30 and 23:30, i then have the set back configured for 18oC which sets back outside of the scheduled times i.e 23:30 - 6:30 and 7:30 - 16:30

The outside sensor is fitted to a N / NE facade about 2/3rd up as recommended
All of the Rads have TRVS set to fully open and i rarely adjust these.

I understand this is a Weather compensator and that the external sensor essentially controls the flow rate temps possibly saving me a few quid - im also using it in room thermostat mode
Am i correct in my understanding here?

Its a single zone system, downstairs is generally warm - i normally tweak the temp up another 0.5 if the rads are cooling, Upstairs however is my issue its generally a lot cooler than downstairs

My thinking is it could be related to the rad in the kids bedroom its single panel
im contemplating upgrading to a dual panel as its normally hot, it just doesnt appear to heat the room as well as others

Im also thinking perhaps it would make sense to install the VRC 430 into the boiler and set to modulating mode and then fit a VR81 room thermostat into the hallway where its generally cooler - i could then adjust the living room TRVs down

Perhaps i could then lower the curve to 1.7-2.1

hopefully this makes sense, any help would be greatfull.

thank you
 
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Hi Andrew,

I have a VRC 430 and it did take a bit of trial and error to set up to suit my house and needs. I found thermostat mode and setting Max. pump blocking to off (0) works best for me.

Getting to your problem, it could be that the rad is too small. Theres lots of tools online to help calculate the correct rad size. Give one a try and if it comes up with a larger rad that currently fitted, this may help.

Hall ways are typically better locations for the thermostat than a living room. Why not relocate the VRC 430 to the hall rather than the boiler and save the expense of the VR81?
 
They are good controls but like everything else, they require a suitable system. If the rads are all heating to approx the same temp but some rooms are not as warm as others then essentially your right, the rad for the cooler room doesnt have a high enough output.

Using modulating controls and lower flow temperature generaly requires slightly larger output rads to work well.

Alternitavley change the curve to increase the radiator temps and turn some of the thermostats in the rooms that are too warm down a bit.

Fitted a few systems with weather comp controls, and they have been very comfotable houses, but I go overboard with larger double pannel radiators and they work well. where it would ever save the money involved in paying for larger radiators is debatable, but the comfort levels were certainly worth the extra.
 
Hi Andrew,

I have a VRC 430 and it did take a bit of trial and error to set up to suit my house and needs. I found thermostat mode and setting Max. pump blocking to off (0) works best for me.

Getting to your problem, it could be that the rad is too small. Theres lots of tools online to help calculate the correct rad size. Give one a try and if it comes up with a larger rad that currently fitted, this may help.

Hall ways are typically better locations for the thermostat than a living room. Why not relocate the VRC 430 to the hall rather than the boiler and save the expense of the VR81?

Thank you ChewChew,

Yes i comtemplated moving the VRC to the hallway but i dont want to start chasing out the backbox into the wall again ideally
Plus the missus finds the VRC a bit tricky to operate whereas the VR81 looks a lot simplier and more like a traditional thermostat

I think i will go ahead as yourself and Scottish Gas man have suggested and upgrade the single panel rad to a double, thanks to you both!
 
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The outside sensor is fitted to a N / NE facade about 2/3rd up as recommended
All of the Rads have TRVS set to fully open and i rarely adjust these.
The Vaillant Installation manual says the sensor should be on a N / NW wall.

Why set your TRVs to fully open? The rooms will not heat up any quicker; and it won't help if the rads are too small.

Have the rads been balanced?

Adjust the curve until the coldest room (TRV on Max) reaches the required temperature; then set the other TRVs to give the required room temperature.
 
I wonder what mental process makes anyone set a TRV to fully open?
 
The outside sensor is fitted to a N / NE facade about 2/3rd up as recommended
All of the Rads have TRVS set to fully open and i rarely adjust these.
The Vaillant Installation manual says the sensor should be on a N / NW wall.

Why set your TRVs to fully open? The rooms will not heat up any quicker; and it won't help if the rads are too small.

Have the rads been balanced?

Adjust the curve until the coldest room (TRV on Max) reaches the required temperature; then set the other TRVs to give the required room temperature.




The outside sensor is fitted to a N / NE facade about 2/3rd up as recommended
All of the Rads have TRVS set to fully open and i rarely adjust these.
The Vaillant Installation manual says the sensor should be on a N / NW wall.

Why set your TRVs to fully open? The rooms will not heat up any quicker; and it won't help if the rads are too small.

Have the rads been balanced?

Adjust the curve until the coldest room (TRV on Max) reaches the required temperature; then set the other TRVs to give the required room temperature.

Hi D_Hailsham,

Thanks for the Balancing info - i'll give that a go.

Andrew
 
Thanks for the Balancing info - i'll give that a go.
I haven't given you any balancing info.

My comments about setting the curve to suit the coldest room etc. has nothing to do with balancing.

Balancing is concerned with ensuring each rad gets the required flow through it. If not done some rads will be much hotter than they should be and some much cooler.
 

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