Vokera 20 80 RS Flowmatic problem

[MD1886]

As the title suggests I am having a problem with an old Vokera.

The system intermittently shuts itself down and the pilot light is extinguished. There seems to be no particular pattern to when this issue will arise.

I am guessing that there is some problem with the air-supply/exhaust system but that may be nonsense.

Nobody seems keen to take a look at this for me. A few plumbers have even suggested that I "bin it and put any money you were going to spend on repairs to a new boiler". That, to me, seems a bit extreme without at least trying to look at what the problem is.

I am wondering if there are any members that have suggestions or if they think this sounds like a known issue?

Failing that, are there any members out there, or someone that a member could recommend, in the Newcastle upon Tyne area, to take a look at this for me?

Thanks

 

[45yearsagasman]

Does the fan continue to run on low speed when the boiler is at rest?
You can detect this by simply checking at the flue terminal, if it is within reach.

 

[DP]

Where in the country are you. Cracking boiler, carry many spares for single visit repair, even overhaul the beast.

But then again I am not a boiler changer just because the one on the wall is long in the tooth.

I say if the old boiler is working well, good controls are in place, old proven technology will reduce you running cost (taking into account silly prices asked for spare parts and procedures required to keep modern steamer ticking over)

 

[MD1886]

@DP

Yes, I've been browsing the other threads and, as you say, it seems a pretty decent boiler; I'm loathe to ditch it.

I've updated my profile to show that I am in Newcastle upon Tyne. Is that within your 'catchment area' ?

 

[Agile]

Bit of a trek from Glasgow!

Could well be the fan is not running slowly !

Tony

 

[MD1886]

OK, I've been making a few more observations and it certainly seems like the fan not running slowly at rest may well be the problem.

I cannot hear the fan at all when at rest- even with the front cover off and me ear against the unit in the upper left corner (which is where the manual seems to indicate the fan is housed). I also cannot feel anything flowing from the flue when the system is at rest (the flue terminal is about 3.3m from the unit)

If I turn on a hot water tap I can hear the system kick into life and what sounds like the fan come on. When the tap is then turned off again I hear the system shut down and what, to me, sounds like a fan spinning down to a halt.

I'm not sure how hot that unit should be when it's at rest but I can tell you that, with the front cover off, the upper casing was almost too hot to touch- this is a couple of hours after the last hot water request.

Is this sounding to you guys like the problem and what are we talking, ballpark, to fix it, provided this is the only problem with boiler?

 

[biscuit77]

Either the pump flow switch or the fan resistor faulty, both easy cheap repairs

 

[DP]

MD, this boiler springs back to life if work as required in the manual, is carried out.

I am almost certain, no manual stipulated service has been carried out on the boiler else you would not be having the difficulty you mention.

I was going to suggest you place your hand above the pilot viewing aperature. A slow running fan would result in cool to touch surface. Fact it is hot, would suggest fan not running. A word of warning here, ensure system pressure is maintained. If the flow manifold is stuck in the retracted position (proving cuircuitry now disabled), burner can fire up with no or little water killing the components within the combustion chamber.

Lack of slow runing fan also pops the seals on the heat exchanger.

What you have will only be repaired by a proper heating engineer. Someone who only fits boiler or repairs by part changing, will not have a scooby how to mend your boiler.

Some of the things that will need to be considered by the person on site.

Check main heat exchanger seals and remove any buildup of deposits
Expansion vessel pressure
Burner cleaing and removal of dust within
Fan impellers cleaned and replace fan seal if broken
Check hot water heat exchanger seals for weeps at the manifold
Check, clean and lube spindles both diaphragm manifolds
Check tail piece- will need replacing quite certain
Check front end, Check if spring distorted. If yes, replace
Check fan slow run ballast resistor
Check modulation during hot water and heating. You should hear a click and burner downsize from max flame
Check low and high rate burn

If you were closer, I would offer to come and fix your boiler. I charge mileage charge for put of area calls. I think Newcastle from glasgow and back would work out a tad expensive.

Wish you luck and hope you get someone to carry out repair on this excellent boiler. If he gets stuck, can offer over the phone guidance to the Gas Safe engineer.

Above is what I would do as a minimum.

 

[MD1886]

@DP - Many thanks for such a detailed reply and your very generous offer to talk someone through any sticky points!

Alas, I fear you are correct about the lack of servicing on the boiler. We only bought the house in late 2010 and I've been a bit lax myself (we've been concentrating on other, seemingly more pressing, matters in the house).

Finally, anybody reading this thread willing to recommend a heating engineer in the Newcastle area?

 

[Agile]

As you say, you have lived there for at least 19 months and not bothered to get the boiler serviced.

They are getting rather long in the tooth but as DP says they are solidly built and when serviced/repaired by someone who is prepared to take the time will give excellent service and are more reliable than the current boilers.

Tony