Help - no heating or hot water

[prettyinpink7890]

Hi

Hope you can help please.

I have a Glow Worm Energysaver 40, which is approximately 10 years old, on a vented system.

The electrical side of the system is normal but the boiler lights then cuts out after a short time. There are gurgling and water knocking sounds from the boiler just before it cuts out. The thermal cut out has to be reset before the boiler will relight.

Merry Christmas.

PiP

 

[ollski]

Check there is water in the header tank and that the pump is working.

 

[prettyinpink7890]

Hi.

There is water in the header tank. Looked at the pump. There appears to be two. How do I test if one of them is working?

Thanks.

 

[prettyinpink7890]

Unfortunately still no hot water or heating. There are two pumps in the airing cupboard, one of which is red hot even though it doesn't appear to be pumping. What do you suggest?

 

[ollski]

Unfortunately still no hot water or heating. There are two pumps in the airing cupboard, one of which is red hot even though it doesn't appear to be pumping. What do you suggest?

You need to get hold of an electrical multimeter and check to see if the pump is receiving 230 volts. If it is and the impellor is not turning when you take the big screw out of the middle you have proven it to be dead and requiring replacement. What are the make and models of the pumps and is it possible that the one which does work is a shower pump?

 

[prettyinpink7890]

I believe one pump is for the central heating and the other is for the boiler circulation. The shower comes direct from the bath taps.

The suspect pump is a Grundfos 15/50 Selectric. I think it circulates hot water from the boiler to the storage tank.

 

[ollski]

I believe one pump is for the central heating and the other is for the boiler circulation. The shower comes direct from the bath taps.

The suspect pump is a Grundfos 15/50 Selectric. I think it circulates hot water from the boiler to the storage tank.

It's perfectly plausible to have a seperate pumped heating and pumped hot water system though that wouldn't explain why one faulty pump would cause you to have no heating or hot water. Give us the details of everything on your system with a power cable to it. Though if you don't have a multimeter to wield there's not much advice to give.

 

[prettyinpink7890]

The boiler fires up OK but the water doesn't appear to be circulating from the boiler up to the hot water storage tank in the airing cupboard, the boiler stays lit for a minute or so, then it begins to gurgle and "Knock" and the thermal overload trips and has to be reset.
When I had a problem with the central heating a while ago I flushed the other pump and it began to work. This led me to believe that one pump is for the heating circulation and the other is to circulate the water from the boiler to the hot water storage tank.
Both pumps are fed from a relay which looks as though it takes a signal from a small box on the side of the hot water tank.
When I checked earlier, the boiler was heating the water, the boiler outlet pipe was warm but the hot water did not appear to be going up to the hot water tank, both the pipes either side of the pump in question were cold yet the end of the pump where the chrome screwed cap is was blazing hot and the pump did not appear to be working.

 

[Paul Barker]

Well done discovering the relays. Make sure electrical connections are working right (sticky relay?)

Anyhow my guess is that you have a water problem, either caused by an empty feed expansion tank or a blocked cold feed pipe. The pumps will get very hot if they are not imersed in water, and get very damaged.

I would be opening both pump bleed screws the big silver one, and manually turning the shaft you'll see a sort of screwdriver slot in it. If both are free, then look into water situation.

If f/e tank is empty/near empty find out why and fix it.

If tank is half full then attach hose to drain off and drain some water out. Does level in tank go down (and float valve refill?)

Yes? Problem is elsewhere.

No? drain system, tie off ball valve bung the cold feed at tank end (because with a blockage in the pipework the water won't drain out) and cut into the pipe at the bottom where it t's into the heating pipe, poke around to get the rock hard black stuff out, maybe need to replace a section, reconnect remove bung, allow system to refill, takes some effort.

 

[prettyinpink7890]

I tried draining the system from the drain cock above the boiler and the feed/expansion tank empties and fills as normal.
I was wondering how the boiler gets it's water and how the water gets from the boiler to the tank once it has been heated.
I have tried removing the silver cover on the pump and although there is a slot, I cannot turn the pump with a screwdriver.
Is it possible that because this pump, if it is for the circulation of water from the boiler to the storage tank, has seized. The system is ten years old and this pump is in use quite a lot.
Also the system seemed to be full of quite dirty water when I drained it.