Water Heating using old boiler

[tecas]

Hi all,

I have an issue with my central heating which I hope someone can help me understand please. It is an old conventional heating setup with a glow worm boiler (circa 1985). The switch for central heating+water heating or water heating only wasn't working, it always stayed on central heating+water heating irrespective of switch position since we moved in. With all the hot weather recently I sourced the issue to the 1 way valve next to the boiler which directs hot water accordingly. The new valve works well but a strange anomaly occurs now. When the switch is set to hot water only, the hot water tank warms accordingly but I get some water coming into the radiators through the "water out" pipe on those radiators. If switch is set to both the hot water comes through the "water in" pipe on the radiators first but at a faster rate and I guess how it should... It's like hot water going in reverse through the radiator when hot water only is selected if that makes sense.

Anyone any ideas why this happens and whether I need extra valves to stop this, or is this some sort of strange feature of the old systems with gravity water systems with 1 valve? To perhaps assist, I have a hot water tank upstairs and a cold water tank in the loft. Thanks.

 

[Dan Robinson]

It is either a blockage in the system.

Or, more likely there is a return pipe for a radiator being tee'd into the return to the boiler after the hot water cylinder connection.


A search for "reverse circulation" should bring the answer up, or maybe by now a suggestion will be offered below in the appropriate box.

 

[tecas]

Hi Dan,

Thanks for the reply. Bringing up the search for reverse circulation gave me a whole host of links. This sounds like the exact problem, I just didn't know the term until now. Will do some more digging around with that term now and see the feasibility of taking this further. Thanks again!