Vaillant VUW242E - Pump O-Ring weeping

[TechD]

Hi,
I have just replaced the DHW diverter valve, which involved taking the pump off. It is held by 3 screws, which seal against the valve by 2 o-rings - which are predictably worn. The manual does say to replace these when taking the boiler off- saying they are included with the pump. However as there is nothing wrong with the pump, is it possible to buy the O-rings individually for this boiler?
I cannot see them sold like that as such.
I have cleaned the old ones up as best i could, and smeared with silicone grease - but still have a very minor weep when the CH is on.
Thanks for any help.

 

[ollski]

standard 17 x 24 x 2 mm washers. GC no. E95980 or manufacturer part no. 981152. Did you try a little bit of fernox lsx?

 

[ChrisR]

TechD do you mean O rings (rubber, once round!) or flat washers cut from fibre sheet?

 

[TechD]

I am convinced it was a rubber O-Ring on the pump The problem o-ring sits in a circular groove in the pump housing which then mates to the flat brass body of the diverter valve. I was planning to use some Jet Blue (from plumb center a while back) multipurpose sealant on the o-ring surface if it is still weeping at the weekend.
As its all fitted back together now I cannot measure the size of the o-ring - but reckon its prob about 28mm? by 3mm thick.

I would have thought these things need replacing all the time when the pump has to be removed when the DV is replaced or overhauled - the service manual says they have to be..... so why dont they supply them with the DV......a typical 2 pence part missing...
Thanks for any suggestions or part nos.

TD

 

[DarkInferno]

I always replace them... then again I have a O-ring set that makes things a whole heap easier.

You might be better off removing the pump/seals taking it to merchants and getting some matching orings, smear with silicone lube and tighten the pump evenly and firmly onto them.

You don't want JetBlue in this situation.

 

[croydoncorgi]

To reinforce the point...
You MUST NOT seal O rings into place. Generally, if they can't move, they won't work properly and will leak. The principle of operation is that pressure on one side of the ring pushes it against a carefully-shaped seating and seals the joint. The higher the pressure, the tighter the seal.

Remember the Challenger? Frozen O ring - leaking gas seal - BOOM!

 

[ChrisR]

As I have a new pump in my mitts - O rings they are. One by ruler is 28.5 or so mm dia, the other 25, And 3mm thick.

Oddly the smaller one is silver-grey and the larger, black.

Nearest standard sizes seem to be imperial, 1 " and 1 1/8", 1/8" thick.

Poke around the RS cat:
http://rswww.com/cgi-bin/bv/browse/...=ukie&3290669269=3290669269&catoid=-101533771

 

[TechD]

Thanks ChrisR - rather than take a risk with a "slightly wrong" size - do Vaillant actually sell these O-rings as individual parts - and if so what are the part no's? I can imagine the problem occurs often when replacing these parts.

I have replaced the DHW Diverter valve - which in turn has some o-rings on it- eg going one going to the DHW heat exchanger- which would need replacing if taken off - yet the new DHW exchanger doesnt come with an o-ring - nor does the completely new DHW valve!! - yet this ring connects the two items - and it cannot be much to ask that the rings are supplied with these factory parts...
The reason for asking is I have aquired a new DHW exchanger via ebay cheaply - yet dont want to fit it without having the "right" o-ring - as there is no prob with the present set-up - and i can imagine nothing but probs without NEW o-rings being fitted.

Thanks for any further guidance.

TD

 

[ChrisR]

Usually a bit of silicone grease is all the old O rings need. If that fails then clean off and use Fernox ls-x, which sets soft.
I agree with you about the need for spares. But even wit the exploded diagram in front of me I can't see quite which the O rings are. Time for a call to Vaillant Tech. Give a number like 123245 for corgi. To say you need to be corgi regd for a job like this is daft.
Hope you get the guy who sounds like Farmer Giles rather than the one with the Spanish accent.
SLightly oversize O rings generally work OK. Heaven knows what the materials are though.

 

[ollski]

sorry I was looking at the wrong boiler vcw 242 Whats the gc number of the boiler you want parts for....I've got part numbers for the o rings on the vuw 242EH gc 4704425 but they are are bit smaller than what you have said.

 

[ChrisR]

I imagine it's a VUW 242E.
Though the spare parts cat photocopy I have (8026 74 09/96) for that model makes it look like there's 2 washers 98-2442 which is obviously wrong.

DO Vaillant release these parts cats? I've got their little quick parts finder which is limited.

 

[ollski]

I can't find any reference on my material to just a 242E.....they all have extra letters on the end. Will make life much easier with a gc number.

 

[TechD]

The boiler is a Vaillant TurboMax VUW 242E H, G.C no 47-044-25. Hope that helps with identifying things.
Thank you.

 

[ollski]

sorry about that...post fell off the bottom of the screen and I forgot. The parts you are after are:

22 x 3mm rubber packing ring man.part no. 98-2331
19 x 3.15mm packing ring. man. part no. 98-2442

 

[TechD]

Thanks very much ollski, as a final fav, could you tell me the part no for the O-ring which connects the DHW exchanger to the Diverter valve, there are 4 connections - 3 are by flat washer, and 1 by o-ring.
Thanks very much.