vokera combi boiler - heating turns on itself on

[jcoulthard]

Hi can anyone help me please. We have a vokera combi boiler which seems to be spooked.

It is starting to turn itself on at odd times of the day and night. I have turned everything off, but it is still coming on. It starts up with the green light on, then after 5 minutes the red light flashes once, then goes back to green. This happens a few times, then it settles down to a continuos green light. Until it decides it's had enough, and turns itself off.

HELP

The boiler is only 7 years old.

 

[DP]

Vokera have made many boilers, a fair number of which are combi boilers

To say you have a vokera combi boiler makes no sense.

 

[ianmcd]

can you tell us which model of Vokera you have ? and whether the radiators heat up on the ghost firing or if the boiler goes into overheat lockout and needs re set ?

 

[jcoulthard]

It's a vokera 28 combi boiler, and yes the radiators are heating up.

 

[McCombi]

We still need the model. 28 Indicates the kilowatt rating. If there's a flap to pull down look there or look for a label under the boiler. It should say something like compact, linea , unica etc. If u can't find it can u post a picture?

 

[jcoulthard]

compact

 

[ianmcd]

OK as your radiators are heating up you need to have the system thermistor changed, this thermistor incorporates a frost protection thermostat and is out of calibration so the boiler thinks it is below 5 degrees C and is bringing the boiler on to protect itself, if the boiler was locking out on overheat it would be the domestic hot water flow switch sticking, I would recommend changing the DHW and the CH thermistors at the same time as they are prone to failing they arent expensive I am Vokera engineer and this is a common fault with the Compact

 

[jcoulthard]

Thank you for your help, it is very much appreciated.

I have noticed in the last few weeks the hot water temperature has been fluctuating. Would this tie in with the other problems.

Once again, thank you.

 

[gbgasman]

Hi ,I am experiencing the same problem with a compact 29he, primary thermister , pcb and ign pcb all replaced to no avail. external controls are tickety boo, only does it when selector switch is in hw&ch mode never on hw only mode. . Any ideas would be greatly appreciated.

 

[DP]

If you have replaced the two pcbs, why not carry on and replace th pump, fan, heat exchanger etc. You will eventually fix he fault

 

[gbgasman]

Haha , I hear ye , Im looking for any constructive ideas, no any wido comments , . And FYI I have inherited this debacle after these parts have been replaced MATE ,

 

[jcoulthard]

Sorry but I really need some help. I am trying to help the engineer to fix my boiler. Thank you ianmcd for your help.

 

[gbgasman]

Start off by replacing both thermisters, this could repair your hw issues. They are not too expensive and should only take 30mins or so to replace, also I would remove the fan assembly to check the small flue Venturi is clear off all debris.

 

[ianmcd]

Jcoulthart you dont need to take the fan out on a compact to check the venturi it can be removed with the fan in situ simply take one screw out of the venturi mounting plate if this is partially blocked you will get fluctuating hot water which as I gather wasnt your origional problem but if that is happening an easy test is to get your engineer to remove the combustion cover and then run the HW if it runs fine with this cover removed then it will most probably be a restriction in the venturi, a very easy fix

 

[ianmcd]

gbgasman sorry for the rude comments in reply to your request some people on here dont really get the request to share our experiences what is the problem you are having with the compact He ?