Potterton Puma wax capsule

20 Nov 2007
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United Kingdom
Anyone know how to fit a wax capsule to the diverter valve of a Potterton Puma 100e. Do you have to take off the whole valve?
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I know how

and no you dont

but I would recommend you replace the whole thing

I dont think you can buy the wax cap as a seperate item anyhoo
Thanks for quick reply.

I already have a wax capsule, £27 seemed a lot for tiny part but a whole valve is very expensive.
yes it is a lot

still dont recommend you just replace that though

do a search and you will find out how to do it
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The fault finder chart says replace the wax capsule so why change the whole valve? Search engines reveal nothing on how to do it.
Drain boiler.

Remove brass nut facing you on DV.
Pull out old wax capsule, insert new.
Replace brass nut and refill.
If you brown, black, or grey matter inside when you take off the front of the valve, you would do better to replace the whole valve and get the system cleaned
i am expecting delivery tomorrow of a new capsule.

i've already taken the existing off.

found that i needed a socket to get the brass nut off. there are 3 O ring washers on the capsule which the supplier advised need to be transferred to the new capsule. the front 2 appear standard and if worn can be replaced at nearest plumbers merchant (remember go for tighter id if you cant get an exact match). the 3rd is a special and is at the end nearest the nut on the shoulder. it's very thin. i cant help on where to get a replacement if you need one (my own thoughts if it leaks is either ptfe on the thread or stretch a much smaller O ring to thin the section out).

the supplier also suggested using a 15mm copper pipe to help guide the capsule into the assembly.

I took the front of the diverter assembly off (held by 2 grub screws) before I removed the capsule. Not sure this was a good idea as the alignment of the internal actuator bits is a little hit and miss as there is clearance between them and the inside of the diverter chamber. It wasn’t too difficult to reassembly but just worth making you aware.

i think i might have to take the capsule end of the assembly off again to get the old capsule out and the new one in but i am not sure until i try it with the new one (my old capsule was solid in the assembly due to build up of sludge).
This is when the diyer needs experience!

A capsule change from Abcot wont fit (I hope you have not ordered one from them).

Silicone grease will ensure no leaks. (Made by fernox)

Fitted the ABTAP wax capsule this morning and CH now up and running. v.happy chappy.

i had to remove the front part of the diverter “wax capsule head” (held by the 2 grub screws) to get the capsule out of the head chamber.

initially forgot to follow the ABTAP advice to use 15 mm pipe to reassemble - i swapped the seals over in exactly the same configuration including the sort of spring washer and pushed the capsule into the chamber manually, fitted end cap with socket set, reassembled pipes, put the cold water back on and YES a leak through the 2 open holes in the wax capsule head.

then remembered ABTAP advice to use 15 copper pipe to push the capsule into the head. what this does is make sure the outer o ring is pushed fully into the head. this time NO leaks.

NB of caution had to wait probably around 10 mins before the capsule started to work. No idea why.

New wax capsule fitted ch is working perfectly for the first time since we moved here in Dec 07.

No hot water, not even a drop from the tap of any water

The water supply is getting as far as the diverter valve under normal pressure (got squirted in the eye undoing front nut).

Before changing the diverter the hot water was working perfectly but rads took hours to get lukewarm.

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