Hot /cold/hot/cold etcetc... help !!

[dalebear]

Hi Matthew, its going off and on...
Jim

 

[xr4x4]

Hi Paul...me again!
do you have a Sierra XR4x4 then ?
jim

No mate, used to.

I've always used this username and it's kinda stuck.

 

[MJN]

If you take a look under the boiler, with the metal grate removed, you should be able to see the diverter valve - a large brass affair with a small plunger at one end that makes contact with a microswitch. It is this movement, and closure of the microswitch, that triggers the HW demand from the boiler. Can you see if this plunger is going in and out rather than staying out (and closing the microswitch) permanently when the shower is on?

If the plunger is failing to stay out then I'd still suspect a failing diaphragm, albeit one that is too far gone to be worked around with the tap test I mentioned.

Mathew

 

[dalebear]

Hi chaps..
just had a look at below the boiler to see if the plunger is moving at all towards the microswitch, and theres nothing moving at all. Im kinda assuming that its visibible within a black cover that attached to the large brass pipework. I had a look at the instruction manual thats still here and it looks like thats the thing thats not moving.
The plumber (remember him?) has asked a heating engineer to come and fit a replacement if i buy the part....sounds fair after a mis-diagnosis...
Jim