Baxi 80e hot water

23 Nov 2006
Reaction score
United Kingdom
I have a Baxi 80e combi boiler and the hot water will not fire unless the tap is turned on full. Central heating works fine. Any suggestions??
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Anyone care to expand on this a little?

I have exactly this problem. Is there something I can adjust?

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The diaphragm is a rubber seal that fits inside the pressure differential assembly.
It pushes a pin onto the microswitch when you turn on the hot water.
If it has a hole in it it may be sruggling to push the pin all the way until you turn the water on full and provide more pressure.
You can get a diphragm for a tenner, I bought one off ebay the other week.

For a diagram of where it fits go to and browse to baxi/boiler/combi/combi 80E/parts list/combi 80e/HYDRAULICS.
The hot water diaphragm is located in part 103, pressure differential assembly.

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