Vaillant 242/282 EH - Shower going hot and cold

[willi1972]

How do,

i have a problem with my combi boiler, which is a vaillant 242/282 EH. Problem i have is with a mixer shower that has been fitted, in that water will run hot then cold. The shower was ok when it was first fitted aprox 6 -7 months ago. but over the last 2 - 3 months the problem has started.

I thought it may be shower at first, but having left he shower running while i sit listening / watching the boiler i have come to the conclusion it is the boiler that is at fault. Reason i have come to this is that when shower is turned on boiler kicks in, after a couple of mins the boiler swithes off and the water runs cold, short time after boiler kicks in again and water runs hot.

Any body any ideas. I am not a plumber and i don't intend carrying out any repairs my self, i just don't want to be told a cock and bull story when the plumber comes out.

Cheers in advance.

Russell

 

[gas4you]

what about other hot taps. do they all work ok and constant?

 

[willi1972]

what about other hot taps. do they all work ok and constant?

Yep other taps working fine. Also after reading a couple of other post i have tried running the shower with another hot tap turned on slightly, and the shower works fine. as soon as i turn the other tap off the shower will run hot and cold again.

Cheers

Russell

 

[gas4you]

Sounds like a lack of flow through the shower.

Do you live in a hard water area?

Try descaling the shower head first, then look for any isolating valves for the shower pipes and make sure they are open fully.

 

[clf-gas]

Would you say the shower is running at the same pressure as first insalled?.
What make/model shower is it?.

Just thinking partial blockage to the shower, though it sound more like a split diaphragm. Not a major job.

 

[Agile]

Slowly turn a tap on and then measure the flow rate at which the boiler just switches on.

It should be at about 2.5 li/min.

If its significantly more than that then the diverter is starting to fail.

If the boiler comes on at 2.5 li/min then it can be because the boiler's gas valve minimum setting is too high! has it ever been PROPERLY serviced?

Tony

 

[willi1972]

Problem has been solved.

There is a filter in the connector from the shower to the shower head pipe. This filter has a rubber o'ring around it. This o'ring had come loose and was blocking the filter, therefore restricting the water flow to the shower head. I have changed the o'ring and shower is working better than ever. More powerful and does not run hot or cold.

The reason i found the problem was because of the comment from 'gas4you'. This is because i was taking the shower head and pipe off to see if it needed de-scaling when i noticed the filter. So cheers for that 'gas4you'

And a big thanks to the others who offered advice.

Regards

Russell