We have a Heatrae Sadia Megaflo hot water cylinder. I need to replace the cartridge in the "hot tap" of one of the shower mixers, but there's no stopcock on the output side of the Megaflo to turn off the hot water.
Is it safe to drain the cylinder by shutting off the cold input, and just leaving the hot taps open until they run dry ?
Thanks.
Yes.
It makes sense to turn off the heat source so that the expanding water doesn't tend to run and drip out while you are working.
Yes, that will work fine.
It will take a surprisingly long time for the pressure in the cylinder to bleed off. This is due to the expansion air volume inside the cylinder. On my 250l megaflo, opening the hot bath tap with the cold supply to the megaflo off pretty much runs a decent bath before spluttering to a stop.
Agreed.
(By the way you won't and don't need to actually drain the cylinder; if there's no mains pressure (ie stopcock off) then no HW will flow.)
And if you open all the other hot taps, especially downstairs, that will empty the pipework and further dissuade water from coming out where you're working.
David
Yes and no...
I would recommend only turning on such taps as are needful..or all off them.
I was doing similar, and accidentally a loo was flushed downstairs..the ballcock opened and let air in..and how water came out of the pipe i was working on ;-) A LOT of it.
Don't count on it if you have a tank in the loft like me..
and someone uses a loo downstairs..
The trick is to empty teh tank as well, if its above the level you are working at.
This is done by e.g. accidentally flushing a loo..air rushes INTO the cold feed to the tank ad allows all the hot water to drain out..
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