Why does Vokera boiler keep going off and on?

blackcloud

Good morning all,

I have a Vokera boiler and sometimes it keeps going off and on when the hot tap is running, like it will fire up run for a few seconds then turn off for a couple of seconds then back on again, over and over and over. So the water gets hot and then cools and then hot again and so on obviously.

Sometimes its ok, and if I turn off the hot tap and back on again but not at full pressure it works fine again. Any ideas what the issue could be? It just had a brand new part, I dont know what it was called now but it completely stopped working and needed a new board or whatever its called in January

I noticed the water pressure it at 0.5 when the boiler is in use and not in use. SHould it be higher? if so, how do I change it?

Thank you all in advance

Alex1983

I would guess your plate heat exchanger is blocked, you could try, as a temp fix try setting the pressure to 1.5 and turn the hot water temperature to the lowest and see if it cuts out, if it does then there is nothing you can do but get it repaired, if it doesn't cut out keep increasing the temperature until it cuts out and keep it set just below the point that it cuts out. That should give you a constant hot water temperature until you repair it.

If im right and it's your plate blocked then it's possible to have it cleaned which may be cheaper then replacing but the reason it will have blocked is black sludge, I would say it will be definitely in your interest to have a power flush and magnetic system filter or a minimum of the filter put on the central heating return pipe to try and stop this happening again.

blackcloud

Thanks for the reply. I have also noticed that since doing this not only does the water go hot and cold but when it goes hot it goes VERY VERY hot, much hotter than what I had programed it to be before it started to stop working properly.

How do I fix try setting the pressure to 1.5?

Its a vokera compact 28 se

It was only 5 months ago that there was NO POWER GOING TO GAS VALVE and the plumber REPLACED PCB WATER IN GAS VALVE FITTED NEW GAS VALVE TESTED OK

southcoastrgi

get the thermistors checked,

to top up the pressure you should have a filling loop (like a silver braided hose between two pipes connected to two valves) one or both with have either levers or a center screw, open one valve then the other slowly (if it has two) you should hear the water going in & watch the pressure gauge it really won't take much water which is why you must open it/them slowly, once upto 1.0/1.5 turn the valve(s) back off

blackcloud

Thanks, There is only a green light which does not go red, well it has in the past but not now. All it does is when the hot water is running the green light goes a steady green and after 5 seconds goes off starts flashing green then fires up again and goes steady green again and then the cycle starts all over again and again.

Alex1983

What model boiler is it

blackcloud

Its a vokera compact 28 se

Alex1983

If it doesn't goto a fault code I would think it has to be temperature related. Still think plate heat exchangers personally, sensors are possible that they are giving false reading but if they were that far out then I think you'd get a fault code, gas valve min and max not set correctly maybe but again think you'd get a fault code.

Don't think there's much anyone can do with out seeing the boiler at this point.

southcoastrgi

Alex1983 wrote: »

If it doesn't goto a fault code I would think it has to be temperature related. Still think plate heat exchangers personally, sensors are possible that they are giving false reading but if they were that far out then I think you'd get a fault code

It doesn't have a plate hex, which is why I said check thermistors 1st before going down the de-scaling route

Alex1983

Southcoast is correct your model has no plate heat exchanger, it has a dual pass heat exchanger, which could be blocked but not as likely.

When it fires for the short time, what does it sound like.

blackcloud

When it fires up and goes off, it just sounds like it always does when it fires up, the goes quiet then after a couple of seconds it fires up again.
UPDATE:
lanlord sent out someone to have a look at it. He said it was the sat and will get the part and come back today, he checked with Vokera who said its not possible for it to be that, so landlord sent out another guy who said that it needs a new gas valve as water is getting in from the outside wall into the gAS valve from the rain as he looked on the outside wall and said the slants were pointing downwards, which is the wrong way around which allows the rain/condensation etc to get into the boiler and into the gas valve.
So I dont know whats going to happen now.