Radiators heating when only hot water programmed.

[Pabster]

We had a Viessmann oil-fired central heating boiler, with some new radiators and piping etc, installed in January and have generally been pleased with it.
However, we are irritated that the radiators heat up, even when only hot water is on.
It is not just radiators which are at the start of the system, but all the radiators on the ground floor, which are affected; they don't just get warm, either - but very hot (there is really no difference between the heat when just HW is on and when the CH pump is on.)
The installer has been back twice. The first time, they said (over the phone, when arranging the visit) that the problem would be bound to be a valve which was stuck open, which seemed plausible, and they left saying that they had 'adjusted' it and we would have no more problems.
On the second visit, their technical guy said that what happens is entirely normal and we would have either to live with it or install thermostatic valves on each radiator.
I'm far from convinced that it's either normal or acceptable, but I'm completely clueless.
I'd really appreciate any advice, which I'll draw on to try to understand what might be going on.
I am thinking of going directly to Viessmann, who have a technical centre near where we live (in France.)
Any experience/advice would be really gratefully received.
Many thanks to all who take the trouble to read this.

Pabster

 

[Best]

Sounds like it has been piped wrong. Reason why I am saying that is because of their "technical guy" on second visit making excuses.
It is not something you have to live with. If you have seperate hot water and rads, that should work.
Depends on what type of system you have - if it has 2 or more 2port motorised valves, they might have done the tee off to rads in wrong place or perhaps more than one tee off to rads. This creates a loop circuit. The tee off should be last tee nearest the boiler, or where pipes divide at motorised valves
Needs another heating engineer to look at it

 

[SimonG]

Is this one of the blue flame ones? And is it a combi or do you have a hot water cylinder? What did you have in before January?

1. It's not something you should have to live with.

2. Something's not working properly or the installer has boo boo'd.

Any pics of boiler and controls?

 

[SimonG]

Forgot. It's in France. Good luck.