I am about to change my bath taps for mixer taps. My hot water come
from a combie boiler. I need to know if i con just run the hot wate until the tank is empty, or will that damage the boiler. can someon please advise me A.S.A.
-- davemo
Are you asking this because there aren't any isolation valves so that the supply of hot and cold to the bath taps can be turned off?
With a hot water cylinder you can turn off the supply to the cylinder and then work on a tap without any flow. This is because the water cannot flow from the cylinder unless air can get in to replace it. It works on the same principal as a pipette where the water remains in the tube all the time that your finger is sealing the top end. Would this not also work for a combi?
In article , Keith Willcocks writes
The main reason you can't empty a hot water cylinder by simply turning on a tap is because the outlet is at the top ;-)
OK, this is a bit confusing... If you really do have a combi boiler (i.e. one that produces hot water on demand) then there probably is no tank.
To stop the flow of water from a combi, all you need to do is turn off the boiler, and then turn off the water at your main stopcock. That will isolate both hot and cold. You can drain the pipe to the bath taps by turning on both taps and then turning on another set of taps lower down (e.g. kitchen).
If you have a heating system with a hot water cylinder, then you need to isolate the cold feed into the base of the cylinder. There may be a valve for this, or you can insert a rubber bung into the outlet of the main cold tank, or you can tie up the ballcock on the tank and drain down.
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