Strange issue with boiler - (Baxi Bermuda 401 - Vintage) - no central heating!

Ramagamma

Hello folks, just fired up the boiler for the winter and booked in a service and i'm having an odd issue, the hot water heats up fine, scalding hot but the boiler refuses to fire up the central heating. I have one of these old back boilers behind a fireplace which has a separate control panel in the kitchen which lets you choose between CH/HW. When I select only Central Heating the boiler in the living room does not fire up, when I select both it fires up but only heats one radiator (in kitchen) and even then only very slightly at the top. 

I have considered switching to a combi boiler every winter for the 10 years I've been here but I've been putting it off until the boiler is out of commission due to the disruption this would cause with vinyl flooring needing lifted etc. Any suggestions or experiences for anyone else in the past or with these boilers in general? I'm not a fan of gas central heating since I grew up with electric (and didn't have to pay the bills!) but the gas fire on it is lovely on a cold winter, can't help but feel its slightly unsafe even with regular servicing and a Co2 alarm.

Any thoughts much appreciated, thank you! 

FreeBear

Yay. Vintage Baxi Bermuda - I've got one of those. Although not the most efficient, nothing to go wrong inside and pretty bomb proof.

If the HW is OK but the CH doesn't work, then it is either the pump or the control/timer at fault - Could be a zone valve if there are any fitted, but a Baxi Burmuda predates that kind of thing..

tacpot12

I concur with FreeBear. The kitchen radiator is probably getting warm just due to some gravity induced circulation on the CH system. If you put your ear to a screwdriver handle and touch the blade of the screwdriver to a radiator you will hear the  pump running if it is running, and silence if it is not. The HW works just on gravity which is why it is working. 

If fact that the boiler doesn't fire up when the controller is set to CH only suggests that it is the controller and not the pump that has failed. If only the pump had failed, the boiler would fire.  

Section62

Ramagamma said:

Hello folks, just fired up the boiler for the winter and booked in a service and i'm having an odd issue, the hot water heats up fine, scalding hot but the boiler refuses to fire up the central heating.

Is there a room thermostat anywhere in the system? If so, is that set to a sufficiently high temperature?

If the pump was to blame (not sure it is) one of the causes could just be it seizing after non-use through the Summer.  That is often something that can be repaired without needing a replacement pump - so if the service engineer tries to tell you a new pump is needed then check to make sure it really does need replacement.

Ramagamma said:

I'm not a fan of gas central heating...

Neither is the government now.

Personally I'd put off getting a combi as long as possible - and before doing that consider the other options the government is going to encourage us all to switch to between now and 203x.

Ballymoney

I don’t know anything about your particular model of boiler but in my old house our CH stopped working every time the pressure fell below 1 bar. Once topped up the CH would kick in again.

FreeBear

Ballymoney said: I don’t know anything about your particular model of boiler but in my old house our CH stopped working every time the pressure fell below 1 bar. Once topped up the CH would kick in again.

Baxi Bermuda is a vented system, so nothing to pressurise. They are really simple things.

Ramagamma

FreeBear said:

Ballymoney said: I don’t know anything about your particular model of boiler but in my old house our CH stopped working every time the pressure fell below 1 bar. Once topped up the CH would kick in again.

Baxi Bermuda is a vented system, so nothing to pressurise. They are really simple things.

Thank you FreeBear, I have always been suspicious of my boiler, having never been used to gas heating as a child it's always struck me as an odd old clunky piece of machinery that might be prone to exploding at any second! We always have a carbon monoxide alarm in the room when it's fired on for the winter and the worst horror stories you hear always involve one that's been disconnected but left in the fireplace. 

I'm determined to keep it going as long as it can, the efficiency doesn't bother me and as long as I can sort out this problem with it not sending hot water to the radiators I'll be smitten! In the 10 years we've been in the flat we've only ever ran it for the winter month's and used kettle for hot water etc so hopefully that's added to its longevity somewhat. 

FreeBear

As Section62 said, it could be the thermostat (in the hall ?) playing up - Check to see what it is set at.

Section62

FreeBear said:

As Section62 said, it could be the thermostat (in the hall ?) playing up - Check to see what it is set at.

Yes, I think the room thermostat or pump are the most likely culprits.

I'd also suggest the OP does try some self diagnosis of the problem before the service person arrives - in case they are of the lazy type who just suck air and say the whole thing needs replacing with a combi.

If the boiler is working sufficiently well to produce scalding hot water then that isn't likely to be the problem.

FreeBear

Section62 said:  Yes, I think the room thermostat or pump are the most likely culprits.

If it were the pump, the boiler would still fire up when the timer kicks in - At least, that's what happens with mine.

Section62

FreeBear said:

Section62 said:  Yes, I think the room thermostat or pump are the most likely culprits.

If it were the pump, the boiler would still fire up when the timer kicks in - At least, that's what happens with mine.

I'm thinking if the system water is so hot it is producing 'scalding hot water' it might be the case that the system thermostat (on the boiler) isn't sensing a need to fire the boiler.  Which might - long shot - be due to a lack of circulation in the CH system due to the pump not running.

Obviously that depends on the state of the system when the OP has tried turning the CH on.  If it was fully cold then (excepting faulty room stat or motorised valves) you'd definitely expect the boiler to at least fire initially.

...that all being a variation of the problem another poster had recently with the system thermostat being set very low leading to short cycling.  In this case the system thermostat must be up high enough, but maybe the circulation water is too hot to call for more heat when the OP is trying the CH.


It needs someone to do a proper diagnosis.... starting with checking the controller to make sure the CH indicator comes on, and (if applicable) there's a click of a relay to energise the CH circuit.

...then move on to the room stat.