Vaillant advice needed

15 Mar 2013
Reaction score
United Kingdom
Hello folks,

Got a few installers coming round over next few days and I want to make sure I know what I'm talking about!

Looking to get a vaillant ecotec plus 637 system boiler with a vaillant unistor 310 cylinder installed. I want to use the vrc470f thermostat/programmer as the system control.

My question is this: Will I also need to buy any additional kit (vr65 control centre) to get them all connected or can it all be done with just the vrc470f

Thoughts/advice would be greatly appreciated

Sponsored Links
The 470 is a weather compensated controller so you need to use the VR66 or VR61 Wiring Center. If you Actually need the 637 (Thats a big boiler) Then the 61 would be best as you can have 2 heating zones as well as hot water control.

Also buy the VR10 Cylinder sensor, gives better control and accurate reading of the cyclinder temperature.
Thanks ScottishGasMan

Looks like I need to add a VR10 and a VR61 to the shopping list :)

Was looking at the 637 as we have a large 4 bed 1930s semi with 2 bathrooms and 12 rads over three floors

Happy to be advised otherwise though :).

Boiler size will be on the list of questions to ask the installers when they come to quote
Sponsored Links
The 310litre cylinder has a coil rating of approx 20kw.

Runnig weather compensation requires that the cylinder and heating are heated seperatly. So The boiler only has to be sized for one load. Not 20 for cylinder and say 10 for house. one or the other whichever is largest.

For your requirements a 24kw (624 boiler) will probably be more than enough.

It will heat the hot water on its own, then switch to compensated heating, and revert to topping up the cylinder occasionally.
we have a large 4 bed 1930s semi with 2 bathrooms and 12 rads over three floors

Boiler size will be on the list of questions to ask the installers
Run through the Baxi Whole House Boiler Size Calculator and you will know your heating requirement. The size of the rads is irrelevant - provided they add up to the heating requirement or more.

As others have said, with weather compensation CH and HW are mutually exclusive, so you need a boiler for whichever is larger.

Ask the installers if there is anything special required to set up the weather compensation, or will it work straight out of the box. If they say: "nothing special", be wary of them as they won't have the necessary experience. But if they mention setting the "heating curve", they know what they are talking about.

Don't suggest a boiler size to them. Let them come up with their own recommendation. You will know what it should be. ;)

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local