In an earlier contribution to this discussion,
wounded horse wrote:

Vot is re-establish air bubble pliz. There are no isolators under
the sink. so I need to know this before I decide to pass on this job.
Thanks

I am by no means an expert on these things. But, AIUI, an unvented hot
cylinder has to have some trapped air above the water, to allow for
expansion when the water is heated - otherwise it would burst. These things
are sufficiently dangerous, anyway, that you need appropriate qualifications
to install them - it's not a DIY job. But I believe that there *is* a user
procedure for re-establishing the air pocket when necessary - typically when
the pressure release safety valve has operated. A friend of mine has got
one, and there are some instructions attached to the cylinder, detailing how
to do this.
--
Cheers,
Set Square
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