Baxi combo boiler staying on.

[Jimchorley]

Ive got this issue with my baxi boiler since I’ve turned my heating on. My radiators are working fine and are hot but when I turn my heating off the boiler continues to run. There is a flashing radiator symbol on the front and it continues to run constantly. If I turn the heating off at the boiler and put it in hot water only mode then the boiler stops running and it looks like it is working as normal, however the hot water is not being heated up in the tank at the scheduled times. When I turn the heating back on at the boiler everything works as normal again but it just doesn’t turn off and the radiator symbol is flashing. When the boiler is running nothing is being heated (either radiators or hot water) unless I turn the heating on at the thermostat.

I had the problem last year and the plumber changed the switches on the divertor valves and that seemed to fix the issue but it’s come back again.
has anyone seen this issue before?

everything has been fine over the last few months when I was just heating water. It’s only happened since I put the heating back on

 

[CBW]

Just sounds like a sticking microswitch in a motorised valve. Which one(s) do you have? That said, you said you can switch to just hot water, do you have a combi boiler?

 

[Jimchorley]

I have these micro switches but they were all changed back in April. Yes is a megaflow compact baxi

 

[terryplumb]

What are you using to turn heating off ? Wall thermostat ,programmer ,or some other means ?
One of those motorised valves is sending voltage to the boiler to fire it up , apparently when you don't want it to .

 

[Jimchorley]

I’ve got a thermostat on the wall. Which when running heats the radiators with no issues. When it is off (as it is now) I can only get the boiler to stop running by turning heating off at the boiler directly by pressing the tap/radiator button That puts it in the tap only mode which I think should heat my hot water at my scheduled time unfortunately it doesn’t

 

[CBW]

Likely one of the Drayton valves, they’re not the best quality.

 

[Jimchorley]

Thanks. I’m assuming that the hot water one is fine as that’s been working ok all summer with the hot water. My house has two heating zones and I only use one of these zones. The problem has been happening since I turned that zone on. Is it fair to assume that it’s the microswitch associated with that zone?

 

[CBW]

Is it fair to assume that it’s the microswitch associated with that zone?

Yes.

 

[terryplumb]

What exactly programmes the hot water cylinder times ?

 

[Jimchorley]

Hi. I use this to program the hot water times.

 

[terryplumb]

So the boiler isn't firing up for domestic hot water ,at the times set by that programmer ?
And when you turn on central heating by the thermostat in your first pic Boiler fires up ,heating works fine ,but continues to run when turned off by said thermostat?
Is all above correct so far ? If so
What exactly do you then do to stop boiler from running ?

 

[Jimchorley]

Yes that’s correct. I put the boiler into hot water mode by pressing this button to turn off the radiator symbol. Doing this stops the boiler constantly running but the water doesn’t heat up at the scheduled time. When I turn the central heating back on by pressing this button again then I can heat up the Water.

 

[terryplumb]

You are going to need an engineer to visit to investigate what's going on .

 

[Jimchorley]

to give people an update on this it’s currently 80% fixed. The plumber changed the switch which fixed it for a day then blew again and the same problem happened. A second plumber came round and put a new switch on and that seems to be working now as expected. the reason I say it is 80% fixed is randomly all day Sunday the boiler just constantly fires up with the same problem. It only happened Sunday and all the thermostats are off! It’s very weird but hopefully will get me through winter!