Vokera 20/80 Rs Flomatic Problems

[24valve]

Hi Forum,

I've been a regular reader, but never a poster on this forum, and I'm now hoping one of you knowledgable folk can help.

Basically, I have a fairly ancient Vokera 20/80 RS flowmatic combi boiler. I have the following faults:

Diverter valve doesnt switch automatically between DHW and CH
System looses pressure (on front panel gauge)

Now, I'm a reasonably competent Diy-er, and would like to tackle the faults myself, besides which two boiler companies that have been out have both said they wouldnt really touch it and have quoted 3.5k to fit a new boiler - argh.

My thinking is that a diverter valve service kit (T0002) would sort the switching problem - the microswitch on the front works fine, but I'm hazarding a guess that the diaghram and associated parts are knackered and need replacing.

As to the pressure - it is wet on the vent pipe outside, so I'm wondering if the heating expansion vessel has had it - this, though, seems like a slightly trickier part to replace, being at the back of the boiler, so is there anything I can do to double check this is the case, before splashing the cash on a new one?

has anyone had any similar problems they can offer any advice on?

Alternatively, if anyone knows anyone in the bedfordshire area who wont go "the whole lot needs replacing, mate", then please forward on their contact details!

I am aware that it probably does need replacement, but I would rather fix this up and keep it running for a while longer.

Cheers in advance,

Neil.

 

[nickso]

You need the DHW diaphragm, T0002 probably has it and it couldn't hurt to change the diverter gubbins too.

Expansion vessel might just need pumping up. Check the FAQ on how to do this.

 

[24valve]

You need the DHW diaphragm, T0002 probably has it and it couldn't hurt to change the diverter gubbins too.

Expansion vessel might just need pumping up. Check the FAQ on how to do this.

Thankyou for your swift reply.

T0002 parts list is a bit wierd - some diagrams seems to suggest it comes with the diaphragm, some doesnt - either way I might as well do the whole lot - it hasnt been done since I've live here (4 years).

I've had a read of the vessel pumping and will give that a go.

thanks again for the advice, much appreciated.

Neil.

 

[nickso]

Should be obvious if you get a look at it, it's the biggest diaphragm of the two in the boiler. Danny will probably know if he sees this thread.

Just realised I was mixing up your boiler with the later excell. You are not very likely to get the diverter gubbins out of the diverter body I'm afraid, the brass ring that holds the lot in can be very tough to get out if it's not been messed with much.

 

[24valve]

Should be obvious if you get a look at it, it's the biggest diaphragm of the two in the boiler. Danny will probably know if he sees this thread.

Just realised I was mixing up your boiler with the later excell. You are not very likely to get the diverter gubbins out of the diverter body I'm afraid, the brass ring that holds the lot in can be very tough to get out if it's not been messed with much.

ah, o.k. thats a bit of a b***er. a new diverter valve is around 102 quid.

needs must I suppose - I'll hang on a wee bit before hitting checkout on the parts, just in case...

 

[nickso]

Just buy the diverter kit and change the diaphragm on its own. If there is still a problem you know what you need after that.

 

[Agile]

If you are replacing the diaphragm then push the manifold pin and see if it moves freely to operate the switch.

They can get seized up if not operated for a while like when the diaphragm fails.

Not one of the easiest of diaphragms to change on that model.

There is also a small spring towards the front which I have seen broken a couple of times but I dont remember if it pushes forward or backwards.

Although they are DP's favourite boiler most others will consider they are overdue for replacement.

Tony

 

[24valve]

If you are replacing the diaphragm then push the manifold pin and see if it moves freely to operate the switch.

They can get seized up if not operated for a while like when the diaphragm fails.

Not one of the easiest of diaphragms to change on that model.

There is also a small spring towards the front which I have seen broken a couple of times but I dont remember if it pushes forward or backwards.

Although they are DP's favourite boiler most others will consider they are overdue for replacement.

Tony

Thanks Tony.

The pin moves freely enough in both directions - actually, if you turn on a hot tap, it'll have no problems giving HW, but once you close the tap, the pin doesnt go back (without pushing it yourself) into CH mode.

Neil.

 

[nickso]

It's not the diaphragm then.

Check the spring in the front of the diverter.

 

[DP]

My thinking is that a diverter valve service kit (T0002) would sort the switching problem - the microswitch on the front works fine, but I'm hazarding a guess that the diaghram and associated parts are knackered and need replacing.

Regret do not know what goodies are found in T0002 service kit, but I would be checking to see if the spring in the diverter is good nick and fee of distortion, tail piece is not leaking and spindle is free to slide in the gland else replace the tail piece, diaphragm is in good condition and domestic manifold cover O ring is healthy, else it should be replaced.

As to the pressure - it is wet on the vent pipe outside, so I'm wondering if the heating expansion vessel has had it - this, though, seems like a slightly trickier part to replace, being at the back of the boiler, so is there anything I can do to double check this is the case, before splashing the cash on a new one?

Not saying it could not be faulty, but have only had to change this vessel one time.

Just realised I was mixing up your boiler with the later excell. You are not very likely to get the diverter gubbins out of the diverter body I'm afraid, the brass ring that holds the lot in can be very tough to get out if it's not been messed with much.

Need special tool for that. But doubt that area needs to be accessed

 

[Agile]

I think my memory is being jogged.

The spring at the front is quite narrow, perhaps about 8mm diameter and I now think its purpose is to aid pushing the pin back after a demand for DHW.

Both I have found failed were broken in two or more places and just not able to push any more.

Of course your diverter valve may just be dirty and stiff. That means cleaning out either physically or chemically ( as I would do ).

If the spring has failed then DP will know the part number. Compared with other makers Vokera seem pretty good with spares for their old boilers.

Tony