Worcester 28CDi expansion vessel replacement

[craigs6124]

Evening all
Just noticed no pressure on the boiler gauge, repressurised it to 1.5 bar, then water started dripping. Found it to be coming from the body of the expansion vessel(pinhole). My questions are:-
1/ Where can I buy one cheap?
2/ How difficult is the replacement? I've recently done the divertor valve, how does it compare to this?
3/ What is the procedure? Manual says....air press switch, fan, flue hood, overheat thermo, central heating sensor, burner, auto vent, gas to water exch, water to water exch, water pump then the exp vessel itself. Seems like a lot! Are there any shortcuts? I do have access to both sides.
4/ How do I repressurise the exp vessel?
Thanks for any sort of help.
Craig

 

[nickso]

don't bother. easily the worst job to do on this boiler and there are a lot of bad jobs on this awful creation.

cap off the expansion vessel feed pipe on the side of the pump and fit a remote expansion vessel elsewhere on the system. this will save your sanity and possibly your marriage, if you have one.

 

[craigs6124]

Thanks for replying.
What sort of remote vessel do I need? What spec(s) do expansion vessels have? (volume, pressure, temperature, connections and the sizes of them). Can you post a link to a suitable replacement?

 

[nickso]

depends on the size of your system but around 10 litres is the norm.

http://www.screwfix.com/prods/97531...-and-Accessories/COMAP-Expansion-Vessel-12Ltr

you will need a 3/4 female to 22mm compression fitting for the expansion vessel and off the top of my head the cdi will need a 1/4 cap. you will obviously need other fittings/pipe as is necessary to fit it your system.

 

[craigs6124]

Thanks again

Next question......can it be installed anywhere on the central heating circuit, or does it have to be close to the boiler. I have one radiator in the (converted) loft. Can I put the expansion vessel up there out of the way?

 

[misterdubya]

Ideally, you should be fitting it on the heating return pipe to the boiler.

 

[ChrisR]

We're usually told they should be close to the boiler - without any reasons being given
I've used thin ones under kitchen cupboard plinths, and on top of kitchen cupboards. The long thin ones

are sometimes easier to hide.
You'll only need 6 litres.

 

[craigs6124]

Thanks again.
From what you've all told me, I think the best option for me, will be to use a space I have to the left of the boiler (about a 5" gap). I think I'll just drill a hole in the boiler housing just to the left of the pump and feed a pipe from the new expansion vessel to the existing point on the pump.

The original pipe from the pump to the (leaking) original exp vessel looks to be 8mm, but opens out to 10mm (I think) at the couplings. Does this mean I should just use plain 10mm pipe for the replacement piece?

 

[ollski]

Tee it off the flow or return pipe from the boiler, dont drill through the casic...nasty.

 

[onlyfitidealboilers]

dont listen to these wollys!

drill out the pop rivits on holding the left hand panel onto the boiler, remove white casing hey presto there is an easy little job in replacing it now!!

I have done this it took m half an hour refitted the case with a pop rivit gun.

 

[nickso]

dont listen to these wollys!

drill out the pop rivits on holding the left hand panel onto the boiler, remove white casing hey presto there is an easy little job in replacing it now!!

I have done this it took m half an hour refitted the case with a pop rivit gun.

assuming there is access to do this of course.

the word is wally's BTW

 

[craigs6124]

I've got the new expansion vessel and I'm about to install it.

How much air pressure should I put into it?

And, do I put the air pressure in before I connect it up, or do I connect it up, pressurise the boiler with water first and then put the air pressure in?

 

[onlyfitidealboilers]

it comes already charged up

 

[craigs6124]

Ah right! Thanks for the reply.

Its got about 0.8 bar in it.

 

[onlyfitidealboilers]

correct