Baxi combi 105e, hot water turns on heating too.

[noncreative]

Hello,

My baxi combi 105e boiler turning on heating when we use only hot water, even if switch is in Hot Water only position.

Changed pcb couple of month ago, hope it will sort out an issue, but it still here.

Do you know what can be an issue?

Thank you very much, this forum is awesome!

 

[Wongfeifox]

Behind the plate heat exchanger (below it) is the bypass pipe if this gets exceedingly hot when DHW is drawn then you probably have a plate blockage.
More than likely it is the diverter passing. Buy the service kit, remove the water section and using a pair of grips unscrew the head from the diverter body, remove the plunger and fit new.
Don't worry about the bottom section (which comes in the service kit) I've never had to replace this as it entails removing the entire left hand manifold.
You don't mention if it is the preheat model as I've another fault on these bad boys.
And I would order the main heat exchanger and bypass orings as a precaution, as the 105's leak from every seal once drained.
If in doubt get an expert in.

 

[noncreative]

Behind the plate heat exchanger (below it) is the bypass pipe if this gets exceedingly hot when DHW is drawn then you probably have a plate blockage.
More than likely it is the diverter passing. Buy the service kit, remove the water section and using a pair of grips unscrew the head from the diverter body, remove the plunger and fit new.
Don't worry about the bottom section (which comes in the service kit) I've never had to replace this as it entails removing the entire left hand manifold.
You don't mention if it is the preheat model as I've another fault on these bad boys.
And I would order the main heat exchanger and bypass orings as a precaution, as the 105's leak from every seal once drained.
If in doubt get an expert in.

Thanks a lot Wongefeifox. I'll need a couple of evenings to digest this concentrated expertise but I have a very good feeling that you are pointing to a right direction

I'll keep an update on my progress.

Ta-da!

 

[noncreative]

Thanks a lot wongfeifox, issue sorted. It was exactly that. I found a nice video on YouTube with some tips and tricks. Ordered service kit and fixed it myself.

Happy now.