Vokera Maxin 28e Boiler

[david3599]

Hi
I have a problem with my Vokera 28e boiler I can get it to run and it fire up and circulates the hot water around all my rads it also delivers hot domestic water to my taps.
The problem is when the boiler shuts off on temperature it will not kick back up again and all the rads go cold until I turn it off and on again.
The pump and fan runs ok no problem the rubber tube to the differential pressure switch near the fan are all ok no holes.
I do not have a room stat I have thermal valve on all but one rad
I have also looped the time clock out to see if that was causing the problem but with no luck
Can anyone give me some guidance to my problem?
Thanks
David

 

[methaneman75]

sounds like its overheating, what is the system pressure at

 

[david3599]

2.5 bar when operating
if it is the pressure high
what could be the cause
thanks
david

 

[methaneman75]

what is the pressure when cold, does it drop low

 

[david3599]

yes when cold 1 bar

 

[methaneman75]

sounds like expansion vessel requires to be recharged slightly but it is not what is making your system faulty. Is the boiler actually locking out, (led illuminating) or is it just idle. Is it when it reaches primary temp (on gauge) or does this happen at any given time and is it more likely to happen when calling for ch

 

[david3599]

hi
its just idle
no red reset lighting up
just runs up to temp then sits there and goes cold

 

[methaneman75]

Sounds to me like the venturis (where air tubes are connected to flue) could be blocked. Power off at spur then take off covers (shouldnt be doing this if you re not RGI but as you have already done this) and remove clamp at fan /flue connection. Take off both air pipes, remember where they go, then theres the 3 screws at flue hood <either side and middle , take off fan elec connections and slide fan hood out. Use spanner to take off two nuts and pipes and give them a clean with a small elec screwdriver internally and externally, then reassemble as above. I would advise getting a local RGI in any case for safety and it is hard to say what it could be for definate without being there

 

[david3599]

thanks
i will give it a go tuesday when I am home from work
will keep you posted
thanks for all your help
david

 

[nickso]

i wouldnt bother stripping the whole thing to bits just yet.

if it is the venturi its usually the upper one and its usually at the t junction between the venturi and the tube that feeds the aps. a 4 mm flat blade screwdriver fits down both venturi nicely, this usually removes any blockages/restrictions.

 

[david3599]

Ok m8

thanks I will give it a go
david

 

[DP]

I would suspect the fault to be elsewhere (remember the boiler fires up every time it runs from cold). Once boiler reaches temperature (anti cycling timer starts running), boiler does not restart when primary temperature dips.

It might be prudent to get the manual out and check for interruption in operate sequence.

 

[david3599]

hi all

and thanks for all your support
the problem was the pcb board transformer burtout
replace with new board running like a new one
thanks again
David