Glowworm Fuelsaver MK2 40B Central Heating problem


28 Jul 2012
Reaction score
West Midlands
United Kingdom

Firstly I have always had helpful answers from this forum so I am hoping someone can advice/help with this issue I have.

I have the above boiler...i know its very old but as I will be moving homes in the near future and with other expenses I am trying to see if this can be fixed without me spending larger amount of money on a new boiler.

The Glowworm has been working fantastic for the last 9 years and I had a gas valve changed last year and thats the only thing I needed doing to it. However due to a leak in the kitchen I had to renovate the kitchen which meant removing the boiler and the control box (switchmaster 600) and putting it back together.

The guy who put it back together was not very familiar with this type of setup and had couple of issues with wiring the control box back but he managed to wire it back but since then we had an issue with the boiler coming on and the thermostat control basically not working properly. So if we use the central heating option on the control box the heating stays on and the boiler is not switching on and off as t used to when the desired temp was reached. Also the radiators take a long time to heat up even if I have the temperature control to max (setting 5). Previously when I changed the control to say setting 3 the boiler would switch off as it would sense a change via the control knob and would obviously come on to keep the temperature at that level.

So now on the CH the boiler just stays lit all the time but if I change it to Water only then change the thermostat setting then it sometimes senses the change and on water it will go on and off.

So my question is, is the control box not working? is it the thermostat? do I have any chance getting this fixed? I am looking for the cheapest option at the moment due to other expenses so if anyone has any experience with this I would really appreciate some guidance.

Many thanks for your help.


Sponsored Links
Get someone in that knows what they are doing, it should not cost that much to have your boiler rewired.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links