On Sunday, 26 April 2020 11:15:47 UTC+1, Kellerman wrote:
On 26/04/2020 10:56, Grumps wrote:
Hi All
Daughter has an unvented hot water cylinder in her flat which has two
3kW heaters. We believe (although I haven't checked as shouldn't really
travel) that the bottom (main) heater has failed and needs replacing.
Apart from getting the correct length and thread diameter of the new
heater, switching off the electric to the timer, and draining the tank -
is there anything else I should look out for when doing the replacement?
I have an immersion heater spanner already.

It's an Albion (now part of Kingspan?) cylinder, 170l Stainless
unvented, SU170D. I can't track down the heater part number which is
14P395 "STAINLES" (sic) but it seems to be a normal 3kW part. I assume
the thread is 1 3/4 but I don't know what the length should be 11" or 14".

TIA for any help.

It might prove a little difficult to undo and unscrew the faulty
immersion element. How old is it? Any sign of additional sealant or
corrosion? They can be very stiff to undo.

If you try loosening it - try first to see if it will move with a full
tank of water so it has some weight to counterbalance the spanner force.
The danger of that is that it might leak afterwards!

Last one I did came undone but distorted the tank slightly.

Unless she cant do without the immersion heater it might be best left
until this virus bollyarks is over and done with -- just in case it wont
undo and (worst possible case) need a replacement tank ?????

--
Ask how to email me.

To easily undo a traditional immersion heater. You need a hacksaw blade with one end wrapped in tape to form a handle.
Use it to saw out the fibre ring, ie work all round the joint circumferentially until its cut right through (you can easily feel this)

Do NOT try to force things if the heater is tight (it probably will be) Use the saw trick
You will heave to clean up the flange afterwards so take a file and emery paper. Put some Plumbers Mait on the new fibre joint.