Worcs Greenstar problem

[mulls76]

Hi, i've got a problem with a Grenstar 30HE combi that i would like some opinions on. Basically what happens is when a hot tap is turned on the boiler fires normally and works perfectly well untill a cold tap is turned on while the hot tap is still running. As soon as a cold tap is turned on the flow switch lowers itself back onto the microswitch and the burner shuts off. The water pressure seems fine throughout the house and the pressure still seems ok even with more than one tap is running. I suspect it's probably just a duff flow switch which seems to be a large spring on this model but I wondered what the superior minds thought on here?

 

[ChrisR]

You'll have to wait for the superior minds.
In the meantime measure the actual flow through the combi/hot tap while that other tap is on. I don't know the figure offhand but I would expect the flow switch to operate with as low as 2 - 3 litres/ minute.

 

[mulls76]

Thanks Chris, the flow rate is definitely still good enough in my opinion to operate the flow switch so I think it may well be a stiff spring on the flow switch which is the culprit. I can't really think of anything else it could be as the pressure seems adequate with both taps running.

 

[ChrisR]

Not a stiff spring, other faults are much more likely! Maybe a holed diaphragm 87005030500. Bit young perhaps for that, but...
Suggest you have a look in there, may need volumetric flow regulator kit
87174020020