Topic: Anyone know about central heating?

[Simon]

My central heating has developed a problem in that it intermittently won't switch off with the trigger from the room thermostat.

My heating is set to be on all the time, but is controlled by a 7-day programmable wall thermostat.  All was working fine up until Sunday night, when I woke at around 3am to find the room was baking hot.  I checked the temperature on the thermostat which read 22C, when the heating is not supposed to come on overnight unless the temperature falls below 10C.

I bought a replacement programmable thermostat which simply plugs into the backplate of the old one, and all seemed to be working fine again... until this morning, when once again, the boiler didn't shut down when it was supposed to.  So, it seems that there is a communication issue between the thermostat and the boiler, but as I have replaced the thermostat, then this must point to a problem with the boiler.  The problem is, I don't want the heating on all the time, and whilst the boiler is ignoring the thermostat, it is constantly on unless I manually switch the heating on and off.

This is a 5 year old Worcester boiler, which does the hot water and heating together. I think they call these a combi boiler.  Can anyone shed any light on what the problem might be before I call out an engineer?

[daveeb]

So is it a modular system in that you simply swap one thermostat for another ? Also is it wired or wireless communication ? Do you get any error lights or codes ?
I'm certainly no expert, my combi boiler is 15+ years old and is well overdue for replacement as we've had several engineers out over the years.
Worcester are a good make though.

[Simon]

The thermostat control is wired, and somehow connects to the boiler.  The actual controller is removable from the back plate and it just connects by 3 pins, so you can replace the controller without actually removing the backplate and accessing the wires, if you see what I mean.  So, the controller is supposed to communicate with the boiler, and tell it when to turn on and off.  That's what's not happening, and having already replaced the controller, I'm guessing it has to be something to do with the boiler.  Someone else mentioned a valve that may be sticking, but I've got no idea where that might be.  At the moment, I've turned all the radiators down low, so as to hopefully control the room temperature that way, and we'll just have to see how that goes for now, until I can get an engineer out to look at it.

[daveeb]

The thermostat control is wired, and somehow connects to the boiler.  The actual controller is removable from the back plate and it just connects by 3 pins, so you can replace the controller without actually removing the backplate and accessing the wires, if you see what I mean.  So, the controller is supposed to communicate with the boiler, and tell it when to turn on and off.  That's what's not happening, and having already replaced the controller, I'm guessing it has to be something to do with the boiler.  Someone else mentioned a valve that may be sticking, but I've got no idea where that might be.  At the moment, I've turned all the radiators down low, so as to hopefully control the room temperature that way, and we'll just have to see how that goes for now, until I can get an engineer out to look at it.

Far more high tech than i'm used to, it does sound like something inside the boiler is failing to turn on or off although you would expect some kind of error message if that was the case. They're quite sophisticated these days.
i'd bite the bullet and get an engineer. Do you have a breakdown contract ? I'm guessing not or you would have probably called someone by now. Might be a good time to get one while the boiler is relatively young, it gets harder to get one as they age. The average manufacturer stated lifespan for a combi used to be SEVEN years  I don't know if that has improved in recent years.

[Simon]

The boiler is just over 5 years old and has an 8 year warranty from new, so I'm not really worried about the cost of repair.  There's a temperature control on the front of the boiler, so I've turned that down a bit, and set all the radiators to medium, and that seems to give a fairly constant and comfortable heat, so as I've got a service booked on the 18th anyway, I'm going to leave it until they come for that and then ask them to look at the other thing as well.

[daveeb]

The boiler is just over 5 years old and has an 8 year warranty from new, so I'm not really worried about the cost of repair.  There's a temperature control on the front of the boiler, so I've turned that down a bit, and set all the radiators to medium, and that seems to give a fairly constant and comfortable heat, so as I've got a service booked on the 18th anyway, I'm going to leave it until they come for that and then ask them to look at the other thing as well.

I'd turn it up again before they come to hopefully demonstrate the fault. I generally find these problems worsen with time so you're best sorting it now rather than finding a possibly temporary workaround.

I'm after a Worcester-Bosch one myself in the not too distant future  so i'm especially interested in how this goes. Is the servicing done by the manufacturer ?

[Simon]

My servicing is done by the installer, who is a local heating and plumbing firm.  Overall, it's been a very good boiler, and I've had no issues with it other than some sort of filter that they had to fit last time in the service.

[Den]

If you disconnect the timer/stat and then turn the power back on, does the boiler still fire up and radiators heat up.

If it does the fault is in the boiler if not then it's in the timer/stat. What happens when you turn the room stat down or set the clock to off?

[Simon]

If you disconnect the timer/stat and then turn the power back on, does the boiler still fire up and radiators heat up.

If it does the fault is in the boiler if not then it's in the timer/stat. What happens when you turn the room stat down or set the clock to off?

I've not tried disconnecting the room thermostat, but when I turn the temperature down, the boiler doesn't switch off.  I think, having already replaced the thermostat, it's got to be something to do with the boiler.  The problem is, it doesn't do it all the time, so the chances are it will work perfectly when the engineer is here. 

[sam]

Do you have homecare or anything? British Gas have been ace when we have developed a range of problems... all covered for a decent price in the year...

[Simon]

I wouldn't allow BG past the front door, Sam, as they tried to rip me off once before.

The engineer came and did the service on the boiler, and as expected, the thermostat worked perfectly.  He said the only other probable thing it could be is the 'white box' valve in the airing cupboard, but when he tested that, it also worked perfectly.  As it happens, it's been behaving itself since, so I'll leave things as they are for now.

[daveeb]

I wouldn't allow BG past the front door, Sam, as they tried to rip me off once before.

The engineer came and did the service on the boiler, and as expected, the thermostat worked perfectly.  He said the only other probable thing it could be is the 'white box' valve in the airing cupboard, but when he tested that, it also worked perfectly.  As it happens, it's been behaving itself since, so I'll leave things as they are for now.

you've got off lightly with BG then 

Glad it's sorted tho', but i hate intermittent faults for the reasons you've just mentioned.

[Simon]

i was contemplating having a new valve fitted anyway, just for the peace of mind of knowing that the issue would be resolved.