Fisherman Mike Posted February 8, 2015 Report Share Posted February 8, 2015 Just replaced the immersion in my cylinder... used a bit of heat and a decent immersion spanner to get it out, cleaned off the boss, threads and all and rubbed down the mating surface with emery cloth so it was nice and clean, took the new one out of the box and alas no fibre washer... So being quite resourceful I cut a 21/2 ins polythene one from the top of an old Tupperware box and sealed it both sides with high temperature copper based gasket silicone. I didn't use any boss white but wrapped the threads of the new immersion in 4 or 5 wraps of PFTE tape before tightening it up by hand and 1/2 turn with the spanner My question is will a polythene washer last ? its seems to have done the trick and everything is as dry as the Gobi. second question, why use boss white and fibre washer anyway...it just goes off like concrete and increases the risk of ripping the tank when changing the immersion. Surely there must be something better. ? Quote Link to comment Share on other sites More sharing options...
biketestace Posted February 8, 2015 Report Share Posted February 8, 2015 Is boss white suitable for potable water ? Quote Link to comment Share on other sites More sharing options...
hmr Posted February 8, 2015 Report Share Posted February 8, 2015 would think the polythene washer will move with heat,personaly never used boss white on imersion heaters fot the reason you stated. just use smear of ptfe paste or tape. Quote Link to comment Share on other sites More sharing options...
vampire Posted February 8, 2015 Report Share Posted February 8, 2015 Just use ptfe tape and plenty of it smeared with lsx and leave cylinder full then its got more chance of not deforming. Quote Link to comment Share on other sites More sharing options...
scotslad Posted February 8, 2015 Report Share Posted February 8, 2015 Slightly off topic, why do plumbers use the PTFE tape and not hemp? Few years ago i was out in NZ and my mate who picked me up from airport is a plumber, gave him a hand with a job on way home. He still uses hemp and says its far better as u can ease it off a tiny bit if needed to get fittings plumb. He's a decent tradesman and worked in UK for years while travelling. Just always wondered why? Quote Link to comment Share on other sites More sharing options...
flynny Posted February 8, 2015 Report Share Posted February 8, 2015 PTFE, Plumbers tape for everything, Atb Flynny Quote Link to comment Share on other sites More sharing options...
Yellow Bear Posted February 8, 2015 Report Share Posted February 8, 2015 Boss white has not been acceptable for potable systems for many years (IIRC in excess of 15 but I can't remember exactly) , if you must use a paste use Boss green or equivalent. On potable systems (and yes DHWS in a house is classified as potable by WRAS) it is advisable not to use any "fibrous" jointing system as it promotes bacterial growth where it is exposed to the water which acts as the medium for legionella. PTFE tape or a "liquid ptfe" are preferable. Quote Link to comment Share on other sites More sharing options...
reggiegun Posted February 8, 2015 Report Share Posted February 8, 2015 (edited) Can't beat the old boss white and hemp. Edited February 8, 2015 by reggiegun Quote Link to comment Share on other sites More sharing options...
Yellow Bear Posted February 8, 2015 Report Share Posted February 8, 2015 Can't beat the old boss white and hemp. True - but if the water board pixies catch you using it on domestic it can get very expensive - trust me I've seen the result Quote Link to comment Share on other sites More sharing options...
seph234 Posted February 8, 2015 Report Share Posted February 8, 2015 Yep i use PTFE and a smear of paste. Quote Link to comment Share on other sites More sharing options...
Blackpowder Posted February 9, 2015 Report Share Posted February 9, 2015 Mike if the cylinder is easy to reach it might be a good idea to replace your ingenious home made washer with the proper thing. Plumbers merchants sell them loose. Ah boss white and linseed oil putty- you could smell a plumber a mile of then. Blackpowder Quote Link to comment Share on other sites More sharing options...
mark@mbb Posted February 9, 2015 Report Share Posted February 9, 2015 Boss white was always ok years ago so was putty and paint the system has gone mad, a lot of old properties still have lead mains Quote Link to comment Share on other sites More sharing options...
figgy Posted February 9, 2015 Report Share Posted February 9, 2015 If your ever stuck without a washer keep wrapping ptfe tape around the top end under the hex of the immersion thread untill it makes a ring when you tighten the immersion in it will spread making its own gasket that won't melt or go soft like plastic might. Quote Link to comment Share on other sites More sharing options...
B725 Posted February 9, 2015 Report Share Posted February 9, 2015 The easiest way to remove an old immersion heater is to cut the fibre washer out with a hacksaw blade just wrap a load of ptfe tape under the flange untill there is enough to form a washer. Quote Link to comment Share on other sites More sharing options...
TheGreenknight Posted February 9, 2015 Report Share Posted February 9, 2015 Get down to you local Graham plumbers merchant they keep them on the shelf and are pence... Quote Link to comment Share on other sites More sharing options...
figgy Posted February 10, 2015 Report Share Posted February 10, 2015 Get down to you local Graham plumbers merchant they keep them on the shelf and are pence... Where's the fun and sense of achievement in doing it right your right in that a fiber gasket will take up a weep where as ptfe won't. Quote Link to comment Share on other sites More sharing options...
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