Vaillant Eco Boiler not working query

[bobbybobson]

Hi all

I have a Vaillant eco boiler at a new house I moved into last week.

It’s a combo boiler and the last boiler I had was old (and much easier to use!)

This one keeps turning itself off. The hot water seems to work and is always warm. The heating also works but for random amounts of time - and increasingly short periods of time. If I set the temp on the boiler to 70, it seems to very quickly increase (often from as low as in the 30s), get to about 52 and then the heating cuts out. The boiler is still on and I understand these have a ‘back up’ which keeps hot water ready at all times and that seems to be working also.

I have found that if I reduce the hot water target temp on the boiler, the heating seems to stay on longer.

Originally I thought it was a thermostat issue as it seemed to work in the evening but have the above problem during the day. However, now it seems to do the above at all times.

Any idea what’s causing it and how I might go about fixing it?

 

[SimonG]

Going to need your gas safe person to have a look.

 

[Lou]

Did you get someone to have a look at it? What was the problem in the end?

 

[Speriment]

It could be numerous things, including a flow problem around the system (clogged up with silt/sludge/scale) or a flow problem in the boiler (badly scaled up). You haven't even given a proper model name nor whether there is any fault code displaying, beginning with an F. If no boiler fault code then a clogged up system would fit your description. The previous owner has run away from the problem 🙂 It's definitely something that can't be fixed online!