Vokera Linea 28 3 way valve problem

[Dan42]

Hi

I've been having problems with the hot water from the boiler for a couple weeks, seemed to be cycling from luke warm to cold in a matter of 5-10 seconds. Having found a few useful threads on here from people having similar problems I managed to determine that the problem lies with the three way valve. Stripped the casing off to find water leaking from behind the motorized valve and ordered a valve overhaul kit in the hope that this would cure the problem.

In the time it's taken for the kit to arrive the boiler has since popped a fuse and is now totally off.

Water has got into the motorized valve so I realise that I'm going to have to replace this too, but I set about replacing the 3 way parts anyway hoping that I could at least stop the water leak and get the boiler back running even if just heating or just hot water.

The kit comprised a new bobbin, O ring, washer, seating plate, rod and cover gasket.

Having fitted the new parts I tried to pressurize the system only to find that I was still getting a leak out of the end of the valve cover, where the motorized valve mounts. looking down the end with a torch it looks to be passing around the control rod where it comes through the brass fitting (gland?) within the 3 way valve cover.

Anyone know if this brass fitting can be replaced? Does the bore become worn? It seems like the rod to bore fit would need to be very precise to stop water passing here and if I can't get it to seal it's pointless fitting a new motorized valve as its going to go the same way as the original.

Any help please? Not fancying a cold, cold Christmas.

Cheers,

Dan

 

[nickso]

Yes it can be replaced. 14mm socket IIRC. Problem is they are often in solid and you may end up having to replace the cover it screws into as well. You will also need the aluminium washer to for the new front seal.

 

[Dan42]

Yeah, I worked out that a 14mm socket on a 1/4" drive manages to fit down the tube just nice, but trying to loosen it with a strong arm bar it felt like I'd bust the cover before it came loose.

So its a new valve cover, new gland and ally washer for the gland then?

Cheers

Dan

 

[nickso]

Yeh, That'll do it.

 

[Dan42]

Cheers nickso,

Parts are ordered 'next day' meaning Monday; a warning for anyone else trying to do the same as me, the first couple places I tried said that the cover and gland nut were obsolete items, I found someone who had no problem locating them at £5ish and £3ish each.

I will report back once fitted.

 

[Dan42]

Just as an afterthought.

There's snow on the ground here and I live in a Victorian house with 10' ceilings so this place is COLD without any central heating on. I'm thinking that it's worth a punt to have a fiddle about tomorrow, given that the only thing stopping me from firing this boiler up is a chitty £3 gland nut. I'm thinking that if I wrap the control rod in PTFE tape it might seal the leak. If I understand this correctly; the control rod has to be pushed in to compress the spring in the 3-way valve when on demand hot water is required, otherwise the spring forces the rod/bobbin assembly back towards the motorized valve and allows flow to the central heating circuit, yes?

So if I manage to seal the rod to gland leak with PTFE tape, but don't refit the (knackered) motorized valve, this should allow the central heating to work? and water from the taps will be heated if I push the rod in manually at the same time (?).

I will try anyway, but advice/experience would be appreciated.

 

[Gasinayr]

A good coating of silicone grease on the pin should be enough to seal it for a few days. Reappy more grease when fitting cover and front seal and you should have no probs

 

[Dan42]

A good coating of silicone grease on the pin should be enough to seal it for a few days. Reappy more grease when fitting cover and front seal and you should have no probs

Thanks for the tip on the silicone grease, worked a treat. Heating now back on and hopefully the DHW will be once the parts arrive Monday.

Given that I've drained the primary circuit a couple times and will have to again when I fit the new 3 way valve cover, will I need to add new inhibitor to the system? And, if I already have it drained, can I just take one of the blanking caps off the heated towel rail in the bathroom (highest point)and pour the inhibitor in from there before refilling the system?

Cheers,

Dan

 

[Dan42]

Quick bump; can anyone advise on the inhibitor?

Cheers

 

[Gasinayr]

Pour the inhibitor in as you asked, through plug on towel rail

 

[timmy74]

them bobbin kits are a tw@t, i aint done one of those for a long time thank god.

 

[nickso]

them bobbin kits are a t**t, i aint done one of those for a long time thank god.

30 minutes tops.

 

[Dan42]

Parts arrived today. All fitted inside 30 minutes (fair enough given I'd already had it apart about three times), system re-treated with inhibitor and back up and running.

Oh the joy of hot running water!

Thanks for all the help and advice.