Vaillant boiler not heating radiators. Please help!

[Rystar00]

Sorry Riley!

I have the vsmart which comprises of a VR65 wiring centre and a separate room stat (comes in the same box)

 

[Riley]

I'm reckoning wiring fault did Vaillant guy check wiring

 

[Stoney Ground]

We then tricked the boiler when it was heating hot water to heat the rads instead (at 70 degrees with burner on max) by manually opening the motorised zone valve. All of the radiators (bar a couple that had dodgy valves which we've now fixed) and all the rads were roasting. So the pipe work and rads are fine.

By doing what I said in post 45, 3 weeks ago you would have proved this.

 

[Riley]

I'd get Vaillant back mate you've proven the system works

 

[Rystar00]

Thanks Riley - I will get them back. They said to change the range rating on the boiler downwards but that's had no effect. I understand from searching other forums that I'm not the first to have had this problem.

Stoned Ground - fantastic advice thank you. I showed your post to my installer (he probably hates me now!) and he followed those instructions to identify the issue.

I will keep you posted on what happens next.

 

[Stoney Ground]

Sometimes it's easier to take away external controls to prove they are or aren't the problem. Maybe ask Vaillant to send a senior technician they need to prove to you there is not a fault with their system.

Have they tried a full factory reset of boiler and controls?

 

[Rystar00]

I thought it might help if I took the boiler from 'auto' under the heating load to the actual load.

I have calculated my rad heat output as 18,137kw so how much should I allow for my unvented cylinder please? 2kw? Would it then be a good idea to set the heating load at 22kw?

Thanks again guys!

 

[Riley]

Right you've proven that your radiators get hot yes ?
You did this by essentially taking the zone valve out of the equation?
I think you are looking at a control or a wiring issue
I'm not sure that there is a kilowatt loadage issue

 

[Rystar00]

Hi Riley,

Thanks again for your support. Your advice has been incredibly helpful and generous.

Yes we have established that the rads get hot (by manually opening the zone valve when the boiler 'thought' it was heating hot water) so the installer agrees and thinks it's a wiring/control issue.

I thought adjusting the load might help as I wonder if the boiler is going into anti-cycling mode too quickly if its oversized? It's probably something as simple as the wiring or controls but I've read other forums that have posts with similar problems to mine and that's what they suggested.

 

[Riley]

Have you got Vaillant coming back I think you are just clutching at straws a bit at the moment mate you need to go at this with a plan rather than just randomly changing stuff in the hope that it will fix it. My suspicion would be that there is an issue with the wiring centre