"YAPH" wrote in message
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On Tue, 29 Mar 2011 01:47:32 +0100, Gazz wrote:

they do a washer that looks like it's a fiber type, would one of those
be better? assuming toolstations washers are fibre??

I've no idea how motorhome immersion heater fittings compare with those
on domestic hot water cylinder immersion heaters, but on the latter I use
a *lot* of PTFE tape wound round the thread and built up heavily onto the
shoulder so that, as the heater is tightened, the PTFE adds to the fibre
washer in sealing the face of the heater flange to the flange on the
cylinder boss.

same as a home one, it's really a boat item, very few motorhomes use the
type of heating system i have fitted to mine, more usefull if you move the
van every day, as you heat the water for free using the waste engine heat,

it's basicaly a mini hot water cylinder, but an unvented one, however it
seems the copper it a lot thicker than a domestic cylinder, to take the
stresses of being full of water and in a moving vehicle/boat at the same
time as being heated to 85 to 90 degrees C.

But alas the sealing surface wasnt the cause of the leak, a wrap of ptfe
tape around the threads, a new fibre washer and some tru blu sealant (which
seems very much like blue hylomar used on engines) and i had the heater to
flange sealed nicely,

then i was able to find the true source of the leak, cylinder had been left
full of water over winter, frozen, bulged, and cracked the apparantly silver
soldered joins,

as it's a pressure vessle i cant get it repaired and re-certified, so need a
new un, nice start to the season,