Another small tank discovered next to header tank???

[specialbeat]

Hi there, whilst snooping around my loft tuther day I realised that there was another tank sat behind the header tank. It has a float valve in it also.
I asked the wife to run some hot and cold water...flush toilet etc but there was no activity there. What could this tank be used for? Oh and the water didn't look too clean either.
Any ideas anyone?
Thanks

 

[Burnerman]

Its the flow and expansion cistern, used in the central heating system.
The tank should have around 4" of water in it.
John

 

[easyflow]

Follow the outlet on the tank and see where it goes.

 

[Onetap]

Typically a 4 gallon feed and expansion tank for the central heating, next to a 50+ gallon tank for cold water storage (H&C taps, baths, etc.).

The F&E tank sometimes becomes redundant if a sealed system boiler is fitted, but the tank isn't always removed.

 

[specialbeat]

Hi John 'Burnerman', so this tank is for the central heating... what is a flow and expansion cistern? Would this be where the water comes from for the rads? Thanks

 

[Burnerman]

This header tank basically keeps the radiators full of water.....as they heat up, the water expands, and the level in the tank rises a bit......as the rads cool again, the level goes down.
The water valve only really comes into operation when (if) you should bleed air out of the radiators or when any work is done......it opens just to keep the water level constant.
Don't be surprised by the amount of grot thats in there - its normal as the water simply isn't replenished regularly.
However, if work should be done on your heating system, its not a good idea for that grot to be drawn down into the pipe work - which is when we get in there with the wet vacuum cleaner to desludge it all!
Its only when I see the old galvanised steel tanks that I get the shivers and strive to replace it....these old things can spring leaks without warning.
John

 

[Armo74]

The feed and expansion cistern is there to top the heating system up and to allow for system expansion on an open vented system.

 

[OwainDIYer]

yes.

The level of the water will go up and down a bit as the system heats and cools and the water in the rads expands and contracts.