Central heating pump and boiler

[Brambles]

A glowworm 50BF is a fairly basic boiler. It does not have a permanent live. As long as the mechanical pilot light is lit, when a live is applied to the boiler, it will fire and run until it reaches operating temperature. Thereafter it will shut off, turning on once the temperature falls below the set point level.

If the boiler is “randomly” firing that can only be because the boiler is receiving a live (+240v) feed and is below the set temperature.

If the boiler has been wired with a permanent 240v supply it will operate 24/7 switching off when it reaches set temperature and on again as the temperature falls below the set point.

In that configuration any external controls may operate the pump and open / close valves, but will not call the boiler for heat - the boiler is operating independently feeding the heating system when the pump runs.

You should not be replacing parts on a whim.

Any credible heating engineer should be able to diagnose and resolve the issue. A heating engineer that has not checked out the control wiring is not credible.

It is also important to know what the system is. Is it gravity hot water and pumped heating or pumped hot water and heating. If it is the latter has it recently been converted from gravity hot water? - That can cause a host of issues if not done properly.

At the end of the day, the boiler will only fire when it is in receipt of a live feed -so your Engineer needs to find out where it is coming from.

 

[John.g]

I was told that it doesn't have a PCB. It is with pilot light. Pump only gets on, when switched by programmer..
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Pump can be switched on by programmer, even when the boiler power is switched off from plug on the wall

"Pump can be switched on by programmer, even when the boiler power is switched off from plug on the wall"
Are you saying that the boiler is just "plugged" into a wall socket?.

 

[nut&bolts]

Thanks, this does clarify a lot about how the boiler and system works

We always had to run the programmer either mannualy or on timer, for hot water and CH. The pump use to come in both scenarios. No modifictions has been made to connections
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"Pump can be switched on by programmer, even when the boiler power is switched off from plug on the wall"
Are you saying that the boiler is just "plugged" into a wall socket?.

Yes , it is. Here is the picture

"Pump can be switched on by programmer, even when the boiler power is switched off from plug on the wall"
Are you saying that the boiler is just "plugged" into a wall socket?.

Yes it is. Here is the pic of boiler

 

[SJB060685]

If the above is correct the system is dangerous and needs to be rectified ASAP. I strongly suggest employing a decent electrician and heating engineer.

 

[nut&bolts]

Oh okay. I switched it off. Let me see if I can get hold of someone today. Thanks

 

[nut&bolts]

Hello all, the problem is sorted. There was an extra live red wire in the wiring box in the airing cupboard that was keeping the boiler on. The electrician checked and disconnected the wire. Wrong wiring was the case for around last 20 years. The boiler appear to have survvied this for so many years!!
Thank you for all the discussions here that enabled to point in the right direction....

 

[SJB060685]

Hello all, the problem is sorted. There was an extra live red wire in the wiring box in the airing cupboard that was keeping the boiler on. The electrician checked and disconnected the wire. Wrong wiring was the case for around last 20 years. The boiler appear to have survvied this for so many years!!
Thank you for all the discussions here that enabled to point in the right direction..

As myself and others pointed out right through this that boilers don't energise on their own, somewhere you had to of been getting this additional feed. Im glad its sorted.

 

[John.g]

It doesn't really matter now and can understand the boiler just firing on/off re that red permanently live wire but once removed would think that a switched wire from the wiring centre would have to be installed or re instated since the circ pump wasn't continuously running with the boiler.

 

[JonnyBagman]

Hi mate not sure if you corrected this, we had a similar problem with Glowworm boiler, after installation, new plumer came out and said the pipes too small, after spending much it still did the same. Turned out in the end to be the mesh filters on the input side to the boiler, output as well had dirt on them and stopped the flow, simple thing that any good plumber should check first. So take the input and output pipes off and clean the mesh fllters, maybe flush the system>