"The Natural Philosopher" wrote in message
...
GB wrote:
I need to drain our Megaflo to replace the immersion heater(s). The
system is a mains-fed one, ie no tank in the loft. I just want to check
the procedure for draining and re-filling the cylinder, please.

1. Turn off cold water feed.
2. Open hot tap and let as much water drain out as the air pressure
thingy inside the Megaflo expels.

open cold tap elsewhere if the cylinder is high. That will drain it pretty
completely.

No, it won't.

The hot draw-off is at the top.
The draw-off pipe extends some short distance down into the cylinder, to
allow for the expansinon volume.

Regardless of how low the tap is, it will only drain as far as the end of
the draw-off pipe, or untill the pressure in the expansion volume is
exhausted. This is not low enough to replace the immersion elements, which
are mounted on the side of the megaflo cylinder.

--
Ron