Baxi Combi 105e - hot water goes hot, cold, hot again!

[Adam75]

Hi

My shower starts ok, the water stays warm but then it goes cold for a while and back to warm.

I cleaned the primary heat exchanger about 2 months ago and it seemed to fix the issue until recently so I decided to do it again over the weekend. I gave it another rinse but there was no crud what so ever. This morning I had the same shower problem!

The 3-way assembly valve is singing but I need to replace a few o-rings as per this post:

//www.diynot.com/forums/plumbing/baxi-105e-high-pitch-noise.346414/#2593442

Does anyone have any ideas why I’m still getting the hot cold water issue? Is this related to the o-rings I need to replace in the assembly valve?

The boiler was only serviced last month!

Thanks
Adam

 

[joe-90]

Do you have the same problem when running the hot taps in the bathroom? It could be your shower thermostatic valve playing up.

 

[Adam75]

I think we do have the same issue with the taps but I'll double check tonight, cheers

 

[Adam75]

Unfortunately I get the same hot, cold, hot etc water issue with the taps!

Any ideas please...

 

[rizanx01]

Hi - I have the same issue - read somewhere that it could be the plate heat exchanger needs flushing/cleaning? Wondered if you have solved your problem or if anyone knows how to diagnose if it is the plate heat exchanger?

 

[oaktyke]

Hi. it sounds like the diaphram washer could be split in the water section to me ! a baxi service kit from plumb centre/ hrp should sort it out about £14

 

[Alfie25]

Do you have any fault lights flashing on the boiler?

 

[Adam75]

Cleaning the heat exchanger did work for about 2 months but the issue came back again. I cleaned it again early December while replacing the o-rings on the 3 way valve (separate issue) but so far no repeat of the hot & cold issue.

If it does come back, I’ll give it another clean & replace the DHW sensor while I’m at it.

 

[Agile]

Could be more dirt got in. Did you have the system power flushed?

Or perhaps you did not clean it properly?

What method/chemicals did you use?

Tony