Radiator and Cylinder queries

liverpoolboy · 3 Jun 2008

A few queries I need answering please ...

(1) If i am to change a thermostatic rad valve do I HAVE to change the tail aswell (if has come with it in the pack) Also do I NEED to wrap PTFE around the threads on the TAIL as well as on the valve body?

(2) If I am to drain my how water cylinder (might need a new one) do I still put the diverter valve (3 position) to the MANUAL position as I do for when draining down the CH water? And is there anything extra I should do when re-filling the new cylinder?

thanks to all...

seco services · 3 Jun 2008

if the tail is the same as your new valve no leave the old one in.
don't wrap the threads in ptfe just makes the nut tight to do up.

you can put it in manual position as you will be draining the complete system not just the coil.

liverpoolboy · 3 Jun 2008

so the manual lever on the motorised valve is to drain the whole system not just the CH water.

I was told to always wrap the rad threads with PTFE tape to make a more watertight fit? so just the compression ring and nut will be OK?

seco services · 3 Jun 2008

thats what the olive is for sealing the valve and pipe.
if the olive is old or worn then yes wrap ptfe round the olive.
but not the threads just makes the nut harder to do up

liverpoolboy · 3 Jun 2008

thank you for your info. i will not use any ptfe tape now! i am going to fit it either this evening or tomorrow as i am off all day! i might even not drain the system and create a vacuum in it instead by bunging the cold feed and vent. thing is i dont have any bungs yet! have you ever tried creating a vacuum? i know how to but i haven't done it before - would most plumbers merchants sell the bungs for a fair price?

1 last point about the rad tails if i may? i know most rad valves are 1/2 inch - so are tails also 1/2 inch standard sizes?

seco services · 3 Jun 2008

use bungs all the time if i can get away with it.
b&q do them for abot £12 or you can get the ones that push in and you screw them up to compress the rubber.

rad valves are you talking about the end that screws into the rad which is 1/2" bsp

liverpoolboy · 3 Jun 2008

the rad valve that screws onto the tail via the compression ring/nut is 1/2 BSP - so the tail that screws into the rad is also 1/2 inch BSP??

Yep those bungs the ones you screw in are the ones I am thinking of. I think the range from 12-17 mm or something (so for use with 15mm pipe) and 16-23 mm or something like that (for use with 22mm pipes)! Might try and get some. How much do you think they'd be in a merchants from experience?

seco services · 3 Jun 2008

check your rad valve as some tails when they join the valve have 1/2 or 3/4.

you can get 6 pipe bungs 2x15 2x22 2x28 from screwfix £12.99

liverpoolboy · 3 Jun 2008

yep i'll measure it!! if it's not 1/2 the same as the valve then i'll have to fit the new tail!!

seco services · 3 Jun 2008

yes you can get a rad key like an allen key that fits inside and unscrews them.

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Radiator and Cylinder queries

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