Baxi 80e & 105e

6 Dec 2010
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United Kingdom
I have a Baxi 80e/105e not sure which cannot determine from casing,the problem is when I run the hot water it fluctuates between hot and cold which can be a bit disconcerting when your standing under the shower.
Whole system was thoroughly cleaned in Oct 09.

Any suggestions what it could be before I shell out for someone to come in.
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Sounds like a blocked secondary heat exchanger.

I have a 105e and had a similar problem. In my case the hot water took a long time to come through...turned out to be the domestic diaphragm.
I ordered a kit replacement off the internet...took a couple of days...

The instruction booklet is very informative on how to replace the diaphram.

The kit comes with replacement (nuts) valves which the controlling needles fit through.. I think it was more likely that the needle was sticking on mine but replaced all anyway. The needle can get a bit of gunge around where it passes through the valve which makes it stick.

Took about 1.5 hours to replace mine. You only have to turn off the cold water supply to the need to drain the heating system. But be careful as the PCB sits just under where you remove the domestic diaphram..which you do not want to get water on...covered mine with two layers of cling film topped with a towel.
Thanks alwest 197.
will try this and hope it works. Will let you know if it cures the problem
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Wasting your money my friend.

The symptoms you describle are not ususally explained by a sticking pin or holed diaphram.

Thermistor or plate heat ex is much more likely
I'm not an engineer so its probably better to take the other gentlemens advice rather than mine...I got the answer to my problem on this site but of course yours may not be the same...mind you at £9.99 post paid for the kit it could be worth a try...

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