Leaking 1950\\\'s cistern

meddyuk · 24 Aug 2007

Hiya. I have a house that was built in the 50's and it has 2 cisterns situated in a cupboard in the spare bedroom. One is the normal black plastic one that you would find in the loft space. This is leaking from the ball cock valve and is full of water and the one i wish to repair. The other is an Asbestos compound tank that is huge. This tank is used for the supply of hot water throughout the house. This drains and refils normally and also has a working ball cock valve. The problem i have is that i dont know how to drain off the black normal tank that is overflowing, as i dont know where it supplies. Both tanks have pipes going to the cylinder that is situated underneath. Hot water, however, is heated via a boiler downstairs.
Does anyone know about this type of system and why i would need 2 tanks. Id like to repair the leaking ball valve.
Many thanks.
Meddy

TicklyT · 24 Aug 2007

It sounds like the smaller cistern is the feed and expansion tank for the heating circuit. The heating circuit runs through a coil of pipe inside the hot water cylinder to heat it, but the water in the two systems doesn't (or shouldn't) ever mix.

//wiki.diynot.com/plumbing:heating_systems

You may be able to drain some water from a drain cock on the radiator circuit to replace the ballcock.

Set the water level in the F&E tank to just a couple of inches above it's outlet.

meddyuk · 24 Aug 2007

Hi thanks for your post. Id love to drain the tank off via a radiator, but the house doesnt have radiators, its got hot air heating. Any ideas?

Meddy

EliteHeat · 24 Aug 2007

Turn off stop tap, scoop some water into a bucket, replace ball valve, open stop tap.

Agile · 24 Aug 2007

Many warm air heaters had a small 3 kW "circulator" as BG called them which heat up the hot water either via a direct or indirect system. It was a small unit to the right ( usually ) of the warm air unit.

I am guessing that is what you have in which case there might be a drain off cock on it.

However, its not worth talking about as you can scoop up a little water out of the feed tank until the level is below the ball valve mounting hole.

You must bend the ball valve shaft so the valve closes when the level is just above the outlet. Thats a total level of about 100-150 mm in the tank.

Tony

meddyuk · 24 Aug 2007

Thanks for your help guys. The leak was coming from the nut that screws in the ball valve so will replace. Do you know what the black tank is used for? Someone said expansion, what does this mean? Can i keep the stop cock in the off position or is it needed, remembering that i no longer use the hot air system of my central heating.

meddy

EliteHeat · 24 Aug 2007

Its the feed and expansion tank for the hot water side of the system. You need it to work properly.

meddyuk · 24 Aug 2007

I thought that the big asbestos type tank was the feed expansion tank, as this empties and fills when i use the hot water, this also has a ball cock.

meddy

EliteHeat · 24 Aug 2007

OK then, it's for the system side. The big cistern feeds the hot water cylinder which is the domestic side.

diynot

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Leaking 1950\\\'s cistern

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