Baxi 105 e central heating comes on randomly on its own

[Greavsie]

Hoping someone can help
I have a baxi 105e and it keeps firing up on its own even when the selecter is turned to just the hot water setting. Its been doing this for a few weeks now coming on at random times during the day and night. The temp on the red neons doesnt get to above 30 degrees though. After a bit of research on the web it has got me thinking that it could be a faulty temp sensor or safety thermostat that relates to the frost protection. If it not this have you lot got any other suggestions? if it is what is the part number that i will need to order?
Cheers kris

 

[powell30]

Is it an 105e or a 105 instant?? Can you post the GC number off the data badge please

 

[Greavsie]

its a Baxi combi instant 105e
the serial number is MBH030656979AB
is this the same as the GC number if not where will i find this
cheers kris

 

[powell30]

I think you will find that the boiler is operating correctly. The instant comes on to heat up an internal store of water held in the expansion tank so as to heat up incoming cold water when a tap is opened. Try turning the water dial to the 12 o clock position (anti clockwise). This switches this function off but doesn't prevent the bolier firing for hot water on demand.

This will save you gas, money and tears too as the expansion vessels will last longer!

 

[hammerswinger]

If you haven't got them these might help....

Baxi 105e instant user instructions

Baxi 105e instant Installation and Servicing Instructions



Cheers.

 

[Greavsie]

I have no pre hot water heat turned on, the central heating is not on, the switch is on hot water only but still the central heating comes on.

 

[baxpoti]

your diverter valve is letting by on pre-heat

 

[Greavsie]

What do you reakon fit a new diverter valve?