Vokera Maxin 28e Boiler

[James7]

Can anyone please help.............!!

New Vokera Maxin 28e Boiler installed in 1998 and radiators renewed in 2008.

System serviced annually.

One day last September, came back from work and my wife said that the Boiler had suddenly had a "violent shaking fit" and she had switched it off.

We switched it back on and it restarted OK.

Over the winter, we had intermittent problems with the red light coming on and Boiler cutting out. Seemed to be that if the central heating was on then the red light might come on when hot water was switched on at a tap. Or the red light could just come on without the hot water tap being turned on.

Normally, the Boiler could be switched back on immediately but sometimes it had to be left for 15-20 minutes, presumably to cool down.

Also noticed that on some of these occasions, the tap water would be excessively hot.

When on holiday for three weeks at Christmas/New Year, we left central heating to come on intermittently and neighbour who was checking daily reported that the red light came on once. He reset.

We now have a leaky joint at the penultimate left hand copper pipe from the underside of the Boiler. Perhaps brought on by the "shaking fit" in September.

Have checked water leaking out with a clean steel nail in a jar and it rusts. Presumably, the Plumber did not include an inhibitor when refilling after new radiators fitted.

After new radiators fitted, with 1 No. additional and a slight increase in some of the sizes, we had problems with the pressure dropping. The Plumber fitted a small expansion tank. This solved the problem and the pressure is now steady at just slightly over 1 bar for long periods.

We called out the Plumber to investigate the red light problem and he removed a 'Restrictor' in the flue pipe which he said was no longer required. However, he could not diagnose the red light fault and thought this could be any number of things.....!!

Over the Summer, with no use of the central heating, we have had no red light problems when using tap hot water only.

Does anyone have any idea why the Boiler would "shake violently" and what the solution to our red light problems could be...........??

 

[bellairaphon]

Is that not the hw outlet that's leaking? Change the thermistor for a start. Shaking violently pump might have stuck or maybe the outer case had shifted. If its not doing it now. Would not worry about it.

Nath

 

[DP]

James, almost certain your boiler has not had a proper service. Violent shaking could be due to stuck component, even dust/ dirt laden problems

Red light is known issue on this boiler that can be easily resolved

Expansion vessel. Too often on is piggy backed when the one in the boiler is in perfectly good order

Very hot water act the start of drawing hot water is a combi boiler thing, if it does not settle midstream to setting on HW thermostat, imperative, hw flow rate verified along with gas consumption used. You should get just under 2.5l from hot tap (even with boiler switched off like you have a present) in 15 seconds. If boiler working, check if temperature gauge (often grubbed) indicates 70 with hot water set at max and hot tap fully open

While not looking for work, have travelled to Edinburgh to carry out service/ repairs. But am sure there will be someone there that knows how this boiler functions to permit good repair.

By the way, restrict or in the flue must be retained if flue length is less than 500 mm (distance needs verifying though)

 

[Agile]

Did your plumber make any effort to recharge the expansion vessel in the boiler?

That can be done as a DIY job so see FAQ if you want to try it.

I am not very impressed by your plumber though. The red light in that situation is probably just needing a small gas adjustment!

Tony

 

[Homesafe]

Shaking was more than likely overpressure and the PRV ( pressure relief valve )doing its job.

Hav you had to top up the boiler regularly before the new expansion vessal was fitted?

 

[James7]

Thanks Guys for taking the time to post Comments.

The basic issue which is causing concern is the Red Light coming on during the winter.

DP suggests, "Known issue that can easily be resolved". Question is what are the likely causes and explanation?

Agile suggests, "Probably needs small gas adjustment".

This is perhaps along the right lines as I can now remember an occasion when the Red Light had gone on, we had switched it off and the gas appeared to be making a sound of flowing through the jets but there was no ignition as viewed through the small glass window.

This reminds me of our previous Boiler where the gas pilot light used to blow out on occasion and we were fairly regularly having to replace the thermocouple.

Any further thoughts along these lines.....??

Regarding the other points:

1) Restrictor removed - It is actually 600mm from the top of the Boiler to the fresh air outside and hence greater than suggested 500mm maximum. [Perhaps not the end of the world.]

2) Expansion vessel - We have had no problems with the pressure since new expansion vessel installed.

3) Hot Water temperature - Get reading of 65 degrees C after running hot water tap hard for 1 minute with temperature control set to maximum. which would therefore appear OK.

4) Violent Shaking - Suggested cause of stuck component, dust/dirt, overpressure relieved by Pressure relief Valve. Not repeated therefore assumed cleared but could perhaps be due to sludge in system. propose to get flushed out and inhibitor added.

In Summary:

Regarding the priority "Red Light Problem", the Service Engineer had suggested perhaps Sludge, PCB, Ignition Box or the Diverter Valve.

Could a new Ignition Box perhaps be the problem bearing in mind comments in Paragraph 5 above and proposed flushing out of sludge in system anyway.......??

How would we be able to replicate the fault bearing in mind that it only appears to occur when the central heating is on.....??

Your further suggestions would be most appreciated.

 

[Agile]

We don't give advice on gas matters to DIYers on this forum!

 

[James7]

I certainly wouldn't attempt to try any DIY on gas matters as obviously extremely dangerous.

Wouldn't even attempt to try any DIY on a Boiler, period.

Simply wish to try and get an understanding of what the problem might be as having a Service Engineer replacing parts on a 'Trial and Error' basis seems rather expensive......!!

 

[DP]

Item 2. If the original vessel was charged and held its charge, then that would have worked correctly too and additional vessel would not have been necessary. Fitting a new vessel and leaving the existing one in place would have the same result. Question is, was a replacement necessary?

65 degrees would suggest slightly below par operation.