Central Heating works fine, but hot water goes cold in 3secs

[Ben B]

Just moved into a new house, it has an oil fired heating system.
The heating works fine, but for some reason, the hot water coming from the taps gets hot, then immediately turns to cold again. Very weird.

Any ideas? The house was left unoccupied for a number of months before I moved in, is there a pressure problem or something? There's a little inline tap on a flexi-pipe towards the bottom of the airing cupboard, my brother says it's something to do with topping up pressure, or restoring pressure? Shall I just turn that and see what it does??!?!?

 

[AlanE]

And the boiler is a? And sysyem consists of??

 

[Ben B]

I didn't make a note of that when I was at the house yesterday (don't have internet there atm) will make a note and add that later. I just wondered if there was some sort of typical reason for those symptoms, like pressure, airlocks or anything?

 

[Agile]

The typical reason is that the part of the boiler which detects the DHW flow has failed!

Tony

 

[Joe07]

i've got the similar problem and I suspect there is something wrong within the shower control, some no return valve is not working and cod water flow into hot water circulation.

 

[bobajob100]

I had this problem but it was with a gas Combi. The problem there was the secondary heat exchanger was clogged and after a friendly plumber cleared it there was no more problem