In article ,
Christian McArdle wrote:
This is only safe if the boiler has a manual reset overheat lockout
(i.e. is suited to sealed pressurised operation). The safety
"mechanism", if you can call it that, for a boiler without an overheat
lockout is to have an uninterrupted vent to get rid of the steam, and an
uninterrupted independent path for quenching water, so it can boil away
merrily until someone bothers to turn it off. With a stopcock on the
feed, it will run out of water and possibly burn the house down.

It was common practice years ago to have no feed at all to the header
tank. Servowarm, for one. And of course the first sign of the level being
low is the upper floor rads not working.

Boilers in those days didn't have overheat lockouts - but I can't remember
it being common for them to start fires. ;-)

--
*Growing old is inevitable, growing up is optional *

Dave Plowman London SW
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