combi boiler water pressure

[tootsy]

I have a Vaillant Combi Boiler.

Recently the boiler does not start up if hot taps are run upstairs. It does start if the hot taps are run downstairs.

Is this a water pressure fault locally?

Cheers Nig

 

[Softus]

Is there a marked difference in flow rate between upstairs and downstairs hot taps?

If so, then the flow switch may be faulty and the flow upstairs just not enough to cause it to actuate.

Can you hear a click from the switch when a tap is opened? (You'll need an assistant for this test).

 

[cross thread]

DEPENDING ON THE EXACT VAILLANT BOILER YOU HAVE,IT IS MOST LIKELY TO BE THE DIAPHAGRAM NORMALLY SHOWS BY NOT WORKING ON UPSTAIRS FIRST.