Vaillant Hot water Problem

[Apeman]

We have a Vaillant combi boiler ecoMAX probably about 8-9 years old. The problem started about 3 weeks ago and is gradually getting worse. If the heating is on when you turn on the hot tap you only get luke warm water.turning of the heating and pressing the ignition button seems to raise the temp 2-3 degrees each time until it is just warm enough to shower.
I think its a problem with the diverter valve but not sureif there is anything I can do before calling an engineer. Can anyone help? cheers

 

[MrV]

When was it last serviced and has the diverter valve ever been replaced?

pressing the ignition button seems to raise the temp

Are you referring to the reset button?

 

[Apeman]

Probably due a sevice now, I think it would be the reset it has a flame on it!

 

[MrV]

Sounds like it may need a part, and possibly a diverter valve and It's well worth getting your service done. They need an annual inspection, and if it hasn't been checked for a while then I'd strongly suggest it.
What I would say is, get someone that knows their stuff on vaillant boilers, There are a few on this site. Otherwise get vaillant out to it.

 

[Apeman]

Thanks i'll get i done straight after christmas