You don't say what type of heating system you have for hot water! I'll give two types. Combination and Standard boiler.
Combi boiler.
The Combi feeds both central heating [sealed system] and hot water via mains feed direct to the boiler. When you turn on a hot tap the boiler ignites. You have to turn off the boiler then the mains water feed to the boiler. check no water comes from the tap/s then you know it's off.
Standard boiler in a house
Gravity fed hot water with airing cupboard storage tank on the first floor. Your hot water storage tank has a cold feed from the large storage tank in the attic [not the boiler header tank]. It is the feed pipe from this tank to the hotwater storage tank you need to turn off. It's usually controlled by a gate valve with a red or blue round turn handle. Some have standard capstan stop cocks. You will also have to check whether it's a gravity fed or a pump fed hotwater system
Pump assisted hotwater systems in bungalows.
Mostly used in Bungalows to circulate hotwater quicker to the farthest fed point.[my kitchen in the bungalow is about 7mt from the storage tank in the bathroom and if it wasn't a pumped system I'd wait ages for hot water to arrive in the kitchen].
The pump acts as a circulatory pump and does not pressuries the sytem. BUT if you are to be disconnecting a tap or pipe in this type of system then you will have to find the pump and close the valve each end of the pump because it's possible to have water pour out of the tap feed pipe when a tap is removed, the pump would recognise it as open tap as it would removing a section of pipe on a low horizontal run.
BOB, February 2005
