Ferroli Modena 102

[combo]

Hi,
Went to a Ferroli modena earlier for a basic annual check. Gas rate was fine, 32kW. The Co reading though went crazy...had my kane 455 bleeping like mad..Co in the hundreds, before the ratio even got to 0.008. this was done thru the test point on the combustion case ( liitle grey stoppas that you pull out ). Cleaned Heat ex and gave it torch and smoke match tretment ( clean anyway ) and checked primary air ports..clean. Ran test again, exactly the same. removed combustion cover...now test was okay. With cover removed I played about with analyser probe and if i stuck it up into where air intake attaches to boiler, everynow and then it was picking up 6-10 ppm Co and giving a ratio valuse ( 0.0009 ).....is this test enough to indicate a dodgy flue or might these just be stray wisps of POC's from the burner chamber with the cover off ?

 

[kris]

Hi combo so when you put combustion cover back was the readings still off the charts? Mind you its a ferroli

 

[combo]

yeah mate.....cover on Co flies upto 280.
I presumed that with the cover off it might be getting clean air from the room, hence the stable and okay readings

 

[kris]

was there access at the flue or the flue terminal just to check readings there to see if any difference,

 

[diamondgas]

Initial lighting can give you wayward CO readings on many boilers in my experience. As long as it settles to within the requirements I wouldn't be too fussed personally

The fact that you're reading minute amounts of co in the air intake could indicate a poor joint and stray POC's as you say. On older boilers the flue connections weren't necessarily as hermetically sealed as modern condensing boilers need to be

 

[kris]

Not sure about this boiler as never been near one , was your gas pressures and pipe sizes ok? what kind of boiler is it ? not make, type

 

[combo]

No, it was upstairs over a conservatory. the flue looked slanted to me ( downwards towards outside ) and had been foamed into the wall...real tight, though the tenant said its always been like that.

Just don't want to have missed something obvious.

 

[combo]

the pipe sizing and gas rate seemed okay....although it deffo looked a diy install to me. It was serviced by BG last year and had been on there contract,

 

[combo]

Yeah, i always allow a boiler to get some temp into it before i analyse. This one had plenty of time, cause I repeated the test a few times. you allow a boiler to rech operating temp, to analyse...thn its too hot to work on !! I was stood around for a while waiting for it to cool.

Im interested to know if an analyser can be used in other ways, not just Co/co2 readings.....is there any tricks or what not...that can help diagnosis. Not sure my sticking the probe in the base of the air intake is a 'scientific' and reliable technique for diagnosis. would 6-10 ppm be enough with the case on to multiply into the big readings I was getting.

 

[kris]

Was the whole flue clear of any ubstructions, so im strugglin to follow you combo, once you put the case back you tested it did the readings go through the roof at the end and it was only when you took the cover off that it simmered down allowing more air in,

 

[smtplumbing]

I had this yesterday i took it the reading outside no hassle

 

[combo]

high readings were only with the cover on. Cover off and they were okay.

Couldn't actually inspect flue. It was upstairs ( ive no ladders long enough ) and was foamed/glued to wall ( annualar sealing ).....

the job has been passed to a Break down eng....but doesn't look good if ive missed something obvious.

 

[combo]

and over a conservatory

 

[combo]

What ?? the readings differed from the combustion cover apertures to the flue terminal
???

 

[kris]

Is the boiler in use at the moment with the high readings?

 

[combo]

No....it was turned off and isolated.....the other engineer was on way

 

[kris]

soz didnt see that youd written conservatory mate ,

 

[kris]

The thing is combo if the flue is intact and theres no obstructions blocking the air ways of the flue then the problem has to be at the burner / gas valve, , but you checked all that but was there any parts of the flue you could say for sure was ok, also was there any fans runing in the house?

 

[kris]

You said by taking the cover off the readings went ok so theres not enough oxygen at the burner sometimes not proper ventilation along with fans will cause this

 

[combo]

Well the internal parts of flue, ie. elbow and the short length going into wall...looked okay but without dismantling ( and then having to reseal to wall etc )and fully inspecting, I wouldn't know about its internal interity. this is the thing with this contrct.....how far do i go on a basic annual service ???
No fans upstairs.

 

[combo]

You man the flue fan ?? Not pulling enough air in ??

 

[combo]

or atleast not pushing the gases out so the atmosphere can push the new stuff in...

 

[kris]

I know its a nightmare and a check is a check but the check then becomes a diagnosis when the readings go off the chart, im telling you combo its because its a ferroli, (buckets), diamond said earlier its a bad joint and it prob will be it just wont be accessible,

 

[stevetheplumber]

baxi solos are bad for high co readings from start up they need at least ten minutes to clear

 

[IDCHAPPY]

Initial lighting can give you wayward CO readings on many boilers in my experience. As long as it settles to within the requirements I wouldn't be too fussed personally

The fact that you're reading minute amounts of co in the air intake could indicate a poor joint and stray POC's as you say. On older boilers the flue connections weren't necessarily as hermetically sealed as modern condensing boilers need to be

This^ Have you checked the terminal and as much of the flue as possible? was the burner pressure ok?
I've seen the BP being too high and the flames licking the bottom on the HE giving crazy reading before.