Intermittent hot water

[galthop]

1) Boiler make / model (gas or oil)
BAXI 105E gas combi boiler (not condensing)

2) What is / is not happening
No hot water when thermostatic mixer shower is started. Hot water works in the kitchen sink and in the bath.

3) Has ANYTHING else been done / changed recently
No.

4) When did it (problem) start
Two days ago.

5) When does it happen? eg, heating coming on or going off
Every time the shower is switched on.

6) Anything else you feel may be of relevance
The shower was fitted 8 months ago and was working fine until this week. I've checked the DHW microswitch in the boiler and that works. The pushrod that pushes the switch moves about 8mm when the bath hot water tap is turned on. When the shower is turned on (even at the highest temperature setting) the pushrod hardly moves.

I can get the shower to work by following these steps:

1. Turn on the bath hot water tap. The boiler starts and we get hot water in the bath.
2. Turn on the shower. Water comes through slowly as most of it is going to the bath.
3. Turn off the bath tap. Flow rate in the shower increases and water is still hot.

The hot water then works fine until the shower is turned off.

The bath and the shower are separate (it's not a shower in the bath).

New information: The basin in the bathroom and the hot tap in the kitchen are also doing the same as the shower - this started today.

Thanks for reading.

 

[nickso]

change the cartridge in the shower

 

[galthop]

change the cartridge in the shower

Thanks for the suggestion, but I don't think it is the shower. Please see the new information that I've added to the bottom of the first post.

 

[Gasguru]

Probably a weak or perforated DHW diaphragm in the boiler. Get the sealing gland changed as well. Cheap parts.

 

[nickso]

change the cartridge in the shower

Thanks for the suggestion, but I don't think it is the shower. Please see the new information that I've added to the bottom of the first post.

was that in the original post?

 

[galthop]

nickso: This is what I added to the original post:

New information: The basin in the bathroom and the hot tap in the kitchen are also doing the same as the shower - this started today.

 

[nickso]

ah so i was right the first time.


probably the diaphragm if the rest are doing it now

 

[galthop]

Thanks for your help.

I've found a few websites selling diaphragms but am a bit confused about which one I need and can't call them as the offices have closed for the weekend.

I'd appreciate it if someone could provide links or part numbers for the bits I need to buy.

Thanks.

 

[Vic Spanner]

5111137 Should get you on your way dear boy.

 

[galthop]

Thank you all for your help, I've ordered the part.

 

[galthop]

5111137 Should get you on your way dear boy.

poxi: I got the part you recommmended and the diaphragm in it is twice the size as the one in the boiler. I took the diaphragm from the boiler and it has split.

Here is a picture of the kit I bought and the diaphragm that came from the boiler.


[/img]

Any ideas about what has gone wrong?

 

[galthop]

I know what I did wrong. My boiler is a baxi instant 105e.

I got the correct part and fitted it and the boiler is working again.


Anyone want to buy a diaphragm repair kit for a baxi 105e?