Old Hot Water System Explanation

anotheruser

I have an older hot water system with a tank.

In the loft there's a large black tank full of water that feeds the hot water tank. I guess water from this comes in from the main via a ballcock valve.
There's a pipe leading from the bottom, which I guess feeds the hot water tank.
There is a large pipe that bends round and comes in at the top. This seems to come from the tank but I can't see where.

In the loft there is a smaller tank. Again, there is a feed in of cold water but I can't quite see where the pipe out would go to or what this tank is needed for.

There's also a small thing connected to a pipe in the loft that deals with the heating. It has a PSI rating on it and a small screw. What is this? What is it for?and should it be tightly closed or a little bit open?

Thanks

Alex1983

The big tank is you cold water tank, your correct it feeds the hot water cyclinder and the pipe that is hooks over the top is called the open vent and will be connected to the hot water outlet pipe on top of the cyclinder. Its purpose is for water to escape if there is a problem with you tank, its a safety pipe.

The smaller tank will be the cold feed tank for your central heating system, the cold feed will be joined into the heating system and normally there will be another pipe hooked over the top like your bigger tank, this is the safety pipe for your heating system, again it allows water to escape if there are issues with your heating system.

Dont know what you PSI thing is, can you post a picture, it is possibly a auto bypass???

Go on google images and search for standard open vented central heating system and plenty should come up.

nickcc

Would imagine the PSI thing is a pressure relief valve.

Ruski

nickcc wrote: »

Would imagine the PSI thing is a pressure relief valve.

Not on an open vented system, there's no pressure - or at least not any that would need a PRV!

I'm with Alex - Bypass valve is most likely (and I bet it's seized )


OP: post piccie of 'psi' item

HTH

Russ

nickcc

If it's a bypass valve that lifts when necessary then I would imagine it's a pressure relief valve.

southcoastrgi

nickcc wrote: »

If it's a bypass valve that lifts when necessary then I would imagine it's a pressure relief valve.

Two totally different things