overflowing

[Ponder]

when central heating is turned ON it empties the header tank. When it is turned OFF it then back flows and causes the header tank to overflow.

 

[bster]

I've pondered but have no idea , but at least i've bumped this up .
(i wanna know what the prob is )

 

[kevplumb]

check the cold feed /expansion aint blocked

magnet is handy

sure somebody will tell you why

 

[Ponder]

cheers guys for ideas, cold feed expansion is not blocked, spoke to a plumber (?) last night he says it could well be a hole in the hot water coil inside the hot water cylinder, with all your experience somebody out there must have had this problem before.

The problem is I have had to turn the water off to stop it overflowing.

Cheers

 

[IJWS15]

Question

Do you have two header tanks (large and small) or is it a combi?

If not a combi is it the small one which empties when the heating comes on - and does the level in the large on rise at the same time? May be difficult to tell if the large one is very large.

If so there is a link between the DHW and the CH - probably a failed coil in the tank. When heating is on the pump is pushing CH water into the DHW and when not on the water pressure from the alrge tank in the loft is pushing water the other way. The water level in the small tank is normally lower than the water level in the large tank isn't it.

I would guess it is not a combi.

 

[62945835]

cheers guys for ideas, cold feed expansion is not blocked, spoke to a plumber (?) last night he says it could well be a hole in the hot water coil inside the hot water cylinder, with all your experience somebody out there must have had this problem before.

The problem is I have had to turn the water off to stop it overflowing.

Cheers

in my opinion that is not the case, unless

when central heating is turned ON it empties the header tank. When it is turned OFF it then back flows and causes the header tank to overflow.

what you said here is the other way round

 

[Ponder]

Ijws15, think you have hit the nail on the head, Have 1 small header tank, and 1 large cold water tank , it' not a combi, at present I have the gate valve to the header (small) tank shut. which stops the problem of it overflowing.
Suppose the only solution is to change the hot water cylinder will keep you informed of the outcome.

 

[Ponder]

1jws15, spot on changed the HW cylinder system works fine and no overflowing, will have to turn temperature down as the water is to hot now may scald if not careful. Will try and find somewhere that can put a pressure test on the suspect coil(pin holes) just to prove the point, will keep you all informed.

Many thanks(1jws15)