Potty Suprima 120L, Loud Vibration On Fire Up

scatmanjohn · 20 May 2006

Has anyone come across a Potterton Suprima 120L that makes a v loud vibrating noise when firing up.

I have cleared the ceramic burner of debris along with the heat exchanger which has made a big difference.

However it will still do it for a few seconds every now and then.

Any comment appreciated.

Agile · 20 May 2006

Have you done a flue gas analysis on it?

It sounds like a weak mixture on start up!

Tony Glazier

scatmanjohn · 21 May 2006

Tony..

The flue is inaccessable so couldn't test it.

I checked the negative pressure at the gas valve which is correct as per MI -1.1 Mb.

Bit stumped really.

Agile · 21 May 2006

I still think its a weak mixture!

Try checking the INLET pressure before and on startup using a WATER gauge with te nipple screw removed or very loose. Might be a sluggish regulator.

Try checking with gas hob on full power.

Possibly increase the pressure to say -0.6 mB and see what effect. First check jet for blockages if above does not offer any clues.

Tony

ChrisR · 21 May 2006

Don't know if they've always been the same but some at least fire up at a very low gas rate indeed - nb the 120's GV is not the same as the rest.
One I checked recently had a working p at the inlet 14mbar at full, correct, gas rate, with about -1.1mb b.p. . All working happily!

Cheap gas valve, though!

Vic Spanner · 21 May 2006

scatmanjohn said:
Any comment appreciated.

Tne noise is called hooting. Is the boiler fitted to a vertical flue

scatmanjohn · 21 May 2006

poxi said:
scatmanjohn said:

Any comment appreciated.

Click to expand...

Tne noise is called hooting. Is the boiler fitted to a vertical flue

It is a vertical flue, about a metre in length.

Do you know what causes it.?

scatmanjohn · 22 May 2006

Poxi?

Vic Spanner · 22 May 2006

scatmanjohn said:
Poxi?

Sorry miles away?

1.Check CO with analyser if poss (Faulty gas valve,Fault on flue)
2.Also check the start up fan speed should ba approx -4.00 mbar on outlet
of gas valve follow MI to adjust
3.There was also a kit produced for the early models that was fitted between the boiler and vertical flue outlet. Phone up technical with serial number they may be able to shed more light on it.

Hope it helps

scatmanjohn · 22 May 2006

Thankyou very much for that Poxi.

Agile · 23 May 2006

Do you really mean check the start up fan speed??? How? And how to adjust?

Or do you mean check the gas valve output at the ( set ) fan start up speed?

Sounds like the weak mixture I suggested originally!

Tony

ChrisR · 23 May 2006

2.Also check the start up fan speed should ba approx -4.00 mbar on outlet of gas valve follow MI to adjust

Poxi You must have better instructions than us mere mortals!
Have I got this right , you're saying the burner pressure goes down to minus4 mbar when the boiler fires even though the fan is going slow for quite a while?
Is the fan startup speed adjustable or do you mean adjust the gas valve, which my MI says is fixed?

How does the Winter/Summer adkustment work. Don't think I've ever noticed one with it on. Presumably it limits the fan speed?

geoff@cetltd · 23 May 2006

IIRC the original Suprima 120s had a 240 volt fan which had a gert big lump spinning at great speed instead of the later low voltage fan

It only need a bit of misbalance for these to shake the house apart

SO ... which type of fan is it ?

Agile · 23 May 2006

Presumably the Suprima 120 PCB MK II no. 5106568 is for the later LV fan ???

And how does the summer/winter switch work and which models had them?

Tony

geoff@cetltd · 23 May 2006

Agile said:
Presumably the Suprima 120 PCB MK II no. 5106568 is for the later LV fan ???

And how does the summer/winter switch work and which models had them?

Tony

There were a few 120 pcbs which were 30/100 derivitives. Same HT transformer, mains fan etc

Later the design was changed to a different HT transformer, sep. flame sense and a LV fan

I've only seen a few of the former, and can't really answer your questions more than that

DO you understand what I'm on about WRT the fans with what's almost a 3"diameter lump of metal (black or green) winging round at a rqate of knots ?

diynot

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Potty Suprima 120L, Loud Vibration On Fire Up

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