vokera 20/80 rs turbo burner and pilot suddenly shut off

[iwilltryharder]

Hello

I was wondering if anyone on here could offer me some advice? My old vokera has been serving me for many years now but recently it developed a problem with the fan whilst I was on holiday. I came back to what sounded like a bunch of spanners in a washing machine. The fan was found to be at fault and replaced but now there is a new problem which wasn't present before the fan was replaced. When hot water or central heating is called for, the boiler will fire and light on its high burner for about 20-30 seconds but then all of a sudden the burner will shut off and the pilot will also extinguish.
I have checked the thermocouple and this is showing at 11mV when the pilot is on by itself in addition to when the main burner is lit.

Does anyone have any ideas what else I could check? I have been trying to get the boiler replaced for the past month but I have had two separate heating engineers call, take some notes and then fail to follow up with a quote even after I chased them! I'm beginning to think I smell bad or something!

If there's something that is a relatively easy fix I will carry it out, which will then allow me time to plan its replacement rather than having to go without heat and water until I can find someone that can install. I'm now off to my parents place for a shower

Thank you.

 

[DP]

Not many of these boiler around. Must be 30 years old now.

looks like you have not fitted the fan correctly. Get a gas repairer in to look at the boiler- bet most have never seen this boiler, so might be worth asking if they know what a 20.80 Turbo is.

Look after a few of these in Glasgow.

BTW what fan did you fit? I mean, what part number.

 

[iwilltryharder]

Thanks for the advice. I ordered from a place online. Stupidly I threw the old fan away but the new one was ordered as being for my model. I'm not sure of the product code but the label on the fan states:

M-V-L RLA97/4200 3030LH-92

Is that any help?
I feel rather stupid for throwing the knackered one away now

 

[Agile]

It sounds to me as if you made a mistake when fitting the fan.

However, we dont give advice on gas/combustion related matters on this forum so you need a gas reg engineer. I dont think its a terribly serious problem.

I went to one of those a couple of weeks ago, also with a fan problem but managed to lubricate it to try to keep it going until the kitchen is extended when I might get the job of fitting a new boiler.

Tony

 

[DP]

Did your fan have a plastic fan to cool the motor and transit clips in place until fan was ready for fitting? reason why I ask is, fan now obsolete but still available from some suppliers.

You may have the wrong fan, or fitting of fan might be incorrect (based on what you wrote)

I dont think its a terribly serious problem

Tony can you suggest why this might not be a serious problem?

OP wrote

the boiler will fire and light on its high burner for about 20-30 seconds but then all of a sudden the burner will shut off and the pilot will also extinguish.

 

[Agile]

Not a serious problem because all the expensive are are obviously working!

 

[iwilltryharder]

Did your fan have a plastic fan to cool the motor and transit clips in place until fan was ready for fitting? reason why I ask is, fan now obsolete but still available from some suppliers.

You may have the wrong fan, or fitting of fan might be incorrect (based on what you wrote)

The new fan has a metal blade which looks like it's designed to cool the fan itself. This is between the fan body and the metal housing. Let me see if I can find a pic......

Identical to this one above. I found it by google image searching 'vokera fan' so I've no idea if it's the correct one but it looks identical to my eyes.

The old one was identical if I remember correctly. No transit clips that I can remember. I tested the fan functioned by wiring it to the mains before actually fitting.

Thanks

 

[DP]

Tony the pilot and burner are getting knocked out. I see that as a safety issue.

OP, that is not the fan for this boiler. The correct number is Vokera 3434, motor is a lot chunkier and shaft extends to carry a 5 blade plastic cooling fan in addition to metal fan seen in the picture

Have a look at following link
http://www.vokeraboilerparts.co.uk/...=VOKERA&partno=3434&app=20-80+RS+TURBO+BOILER

Fan you have fitted might not be moving sufficient quantity of air, resulting in pliot and burner getting knocked out. Look in the glass window when the burner is on. Is the main burner flame swirling about in the chamber?

 

[iwilltryharder]

Here's what I actually ordered:

http://www.euroboilerparts.co.uk/fa115-ferroli-39803860-vokera-4923-3434-206-p.asp

Quite a price difference and it doesn't have the additional plastic cooler either. I now see the 3434 product code - I originally found it by simply searching 'rs turbo 20 80 fan' and it led me to this site which was the cheapest by far... I will contact them.

tks

 

[ianmcd]

Have you checked that the pump is turning and is clear ? if it was sticking or there was a problem with it the same symptoms would happen as the OH stat on this boiler interrupts the thermo-couple

 

[iwilltryharder]

What's the easiest way to confirm the pump is turning? When looking at the pump, is the thing that looks like a large flat head screw supposed to turn when the pump is on?

Thanks

 

[ianmcd]

No that is the bleed screw ,and if that is turning then you really do have a problem, do the 22mm pipes below the boiler get hot before the pilot goes off ?

 

[iwilltryharder]

No that is the bleed screw ,and if that is turning then you really do have a problem, do the 22mm pipes below the boiler get hot before the pilot goes off ?

hah! phew, it's not turning The flow pipe gets hot but the return pipe remains cold, presumably because it's not had chance to circulate back into the boiler before the burner shuts off? I held on to the pipe on the r/h side of the main heat exchanger where the cut off thermostat lives - it didn't get that hot, certainly not hot enough to cause the high limit stat to kick in (if it's working properly)

I am coming to the end of what I can do by myself. Another fan is being delivered just in case this one was faulty in any way.
If that doesn't solve it and there are no further bright ideas, I am going to call it quits and wait it out until someone can come and replace this antique.

Got the fan heater on for now, I just keep telling myself it's a bit like camping.

 

[DP]

Have you checked that the pump is turning and is clear ? if it was sticking or there was a problem with it the same symptoms would happen as the OH stat on this boiler interrupts the thermo-couple

Ian, check your information. You are missing something there. No pump means no burner on this boiler

That is if the boiler has been serviced and is operating correctly.

OP, why not post you location in hope that there is some Vokera guy near you who can pull you out of trouble?

 

[iwilltryharder]

After triple checking the fan and flu connections I turned to the circuit diagram. As far as I could work out the only thing that would cause complete gas valve shut off (burner and pilot) would be the thermocouple and high limit thermostat. Is this correct? As I'd already checked the thermocouple (as per the service manual instructions) I thought I'd temporarily pull the high limit stat off of the heat exchanger pipe and see if that made any difference. Sure enough the boiler fired and ran for a good few minutes before I shut it down. I monitored the temperature gauge very carefully and noted that it never got over 80 degrees. I then clipped the high limit stat back on and switched everything on again. Sod's law the boiler ran fine for about 20 minutes but then cut out again. I removed the stat again, ran the boiler with me hovering over it and verified that it ran fine for about 10 minutes. I then shut it all down and am now looking for a replacement high limit stat as that does appear to have an intermittent fault. Would you agree?

Seems very strange that both the fan and high stat would fail at the same time!

Thanks