Baxi 105HE hot water

[diy mad]

Hi, I have a problem with no hot water from the 105HE boiler. The pin that activates the microswitch on the front of the pressure differential valve isn't moving. The diaphragm was replaced only a month ago.
Is this the sole cause of the pin not moving or could it be another diaphragm within the diverter assembly?
Thanks for your help.

 

[cross thread]

On the cold inlet brass block you will see a 24 mm brass nut on the left hand side, in there is a plastic Venturi that falls apart , replace it

 

[diy mad]

Thanks cross thread but could you explain again in simpleton's language? You don't mean the brass fitting on the front of the diverter with the 2 screws that hold the differential valve on do you? Sorry to be thick.

 

[diy mad]

Ah sorry, I think the pin has dropped. When I said no hot water, what I should have said is the water runs ok but doesn't heat up. Sorry.

 

[diy mad]

Before I remove the nut, I'll obviously have to turn the cold inlet valve off and presumably leave a hot water tap open. Is that correct, I know these boilers have a great dislike of any leaking water that could get anywhere near the pcb.

 

[ianmcd]

Yes that is what you do and cover the PCB housing with a towel, make sure you get all the broken bits of the old venturi out

 

[diy mad]

Thanks ianmcd,
Thinking about it, I seem to remember from a while ago that there's a drain tap that you turn anti-clockwise like a tap on the right hand side of the boiler. Is it necessary to open that too?

 

[ianmcd]

Thanks ianmcd,
Thinking about it, I seem to remember from a while ago that there's a drain tap that you turn anti-clockwise like a tap on the right hand side of the boiler. Is it necessary to open that too?

no that is to drain the primary water (the water that goes to your radiators) you only need to clos the cold water inlet and leave a hot tap open till the water stops running, as you slacken the nut some more water will probably come out of the tap that is normal

 

[diy mad]

Thank you so much ianmcd and cross thread. It's so good to know you guys are there, you must have the patience of a saint. A minor problem to you is a massive one to us still learning. Much appreciated