Glow Worm Space Saver 38 Water Heating

tecas · 11 Mar 2010

Hello all,

We have moved into a house which has one of these ancient Glow Worm Space Saver 38 boilers. The boiler itself works perfectly fine with no leakages that I can see, hence I'd rather keep it right now. It operates off an old Randall 102 controller. On the side of that controller is a switch labelled WATER ONLY and OFF and WATER AND HEATING.

The problem lies when I click on WATER ONLY as the central heating stays on as well as the water heating. The only way to turn the water heating off is to pull the plug on the controller or switch it to the OFF position.

There are two big pipes leading away from the top of the boiler and one small one leading downwards. I guess the two big top ones are supply pipes and the bottom one is some sort of drain. Does this mean that I would have no individual control over the water heating with the number of pipes I have coming away from the unit? It would be great if I had some control over the heat going to the big water tank as we don't need it most of the time, but we obviously do need the central heating at this time of year.

Thank you.

compheat · 11 Mar 2010

have you got a room thermostat fitted ?? this will turn off the circulation pump so you only get hot water.

tecas · 11 Mar 2010

compheat said:
have you got a room thermostat fitted ??

Hi, yes I have.

compheat said:
this will turn off the circulation pump so you only get hot water.

I think it is totally redundant and from an older system perhaps, as it has no effect on the central heating at all.

Any other ideas?

Thanks for your reply.

Andygasman2010 · 11 Mar 2010

well it sounds like it's fully pumped going by the pipes you've described coming off the boiler. sounds like a flow and return (the big ones) and the small one is probably the gas pipe, or maybe downstairs return from the rads? the system is set up so that you can't have heating on without hot water too. have you got a mid-pos, diverter or zone valve somehwere? this may be stuck.

tecas · 11 Mar 2010

Andygasman2010 said:
well it sounds like it's fully pumped going by the pipes you've described coming off the boiler. sounds like a flow and return (the big ones) and the small one is probably the gas pipe, or maybe downstairs return from the rads?

That all makes sense, the two top ones would be supply and return and the small one will be the gas.

Andygasman2010 said:
have you got a mid-pos, diverter or zone valve somehwere? this may be stuck.

Good question. Could they be located anywhere? I have taken the bottom cover off the boiler and there are no apparent valves there.

Thank you.

Andygasman2010 · 11 Mar 2010

these are usually in the airing cupboard with the cylinder but may not be, do u know where the pump is?

tecas · 11 Mar 2010

Andygasman2010 said:
these are usually in the airing cupboard with the cylinder but may not be, do u know where the pump is?

I assumed the pump was in the boiler as I do hear a little noise from the boiler when it's on. I have seen a stop tap on a pipe next to the cylinder and a gauge on top of the cylinder. There is a water tank in the loft that seems to fill the cylinder when I use the hot taps. I will totally empty the airing cupboard soon and thoroughly check for a valve, then I will revert back with my findings.

Thanks for your help.

Andygasman2010 · 11 Mar 2010

have a good look round for a pump and diverter valve, they're not in the boiler

tecas · 11 Mar 2010

Andygasman2010 said:
have a good look round for a pump and diverter valve, they're not in the boiler

Thanks for the information. I have learnt something new already. I will let you know when I find them

tecas · 19 Mar 2010

Hi again,

I have had a good look around and can't find the diverter valve. Maybe I don't have one? I have inspected around the water tank in the airing cupboard and have drawn up a simple illustration of what I have seen. Because of limited access I am unable to take any decent pictures of the whole setup.

On the side of the old Randall rotary controller is a switch labelled WATER ONLY and OFF and WATER AND HEATING. I can't set WATER ONLY.

There is also a thermostat that does nothing in the downstairs lounge also which is strange, maybe it's not wired up to anything... Does the thermostat wire up to the controller alone or the boiler directly? I am trying to figure out where the wires go but they are hidden away in the walls!

To summarise, I have no control over the in lounge thermostat or diverting of the heating to hot water only and I have no idea why

Andygasman2010 · 19 Mar 2010

The two thin copper pipes you describe, to the right on your picture, somewhere between them and your boiler is the pump/diverter set up. If you can't find it you might have to get a plumber or heating engineer in

tecas · 19 Mar 2010

Andygasman2010 said:
The two thin copper pipes you describe, to the right on your picture, somewhere between them and your boiler is the pump/diverter set up. If you can't find it you might have to get a plumber or heating engineer in

I just tried to follow those pipes as much as I could. The pair come out of the airing cupboard and down into the floor (the ground floor ceiling). The only significant noise when the system is turned on is coming from the boiler itself. Thanks for the replies!

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Glow Worm Space Saver 38 Water Heating

compheat

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