Right on the edge of the limit?

[broccoli92]

Had our gas Baxi Combi inspected and serviced today, as it has been every year. Gas safety cert issued and says all okay, but engineer gave what I think was very... ambiguous... advice.

12yo boiler with the following readings on the analyser printout:

O2% = 4.1
CO ppm = 192
CO2% = 9.5
Ratio = 0.002
Pressure (mBar) = 0.02
Temp net (C) = 31
Temp flue (C) = 52
Eff net (%) = 98.7
XS air (%) = 24.6

Engineer said 192ppm combustion CO is approaching "the limit" and says he "initially got 8,000ppm, which would kill you in a few minutes". "It's safe since it's going up the flue", he also said, "but obviously if there were any leaks into the room..." Advised boiler replacement in near future and six monthly checks instead of annually. "I had to let my meter run after the first test to get a lot of fresh air through," he said. When asked if there's a repair option, he said that heat exchanger could be replaced but cost would "approach one third" of total boiler replacement.

Baxi's manual, in the commissioning section, says any CO ratio under 0.004 is fine. I find same figure online more generally. Is there some other limit he could be referring to?

Our CO alarm nearby shows zero for current and peak readings, always has.

And am I correct that, being generous about it, he's misusing his analyser to get a reading of 8,000ppm at some point (I didn't see it)? Taking a reading at the wrong time or location?

Or does it sound like there's a case for boiler replacement here, and I'm being cynical? I don't know anything about boilers, but do I know anything about people? Presumably if there was anything to worry about, the gas cert would have to record that?

 

[ShaunCorbs]

Did he suggest giving the boiler a decent service eg cleaning etc as this is recommended?

Also you never check within the first 5 minutes as the flue gases are stabilised does say in the manual etc

 

[Last Plumber]

When you have it serviced annually, how long would you say it takes?
Has anyone ever given it a full service?

 

[broccoli92]

Yeah, it's been serviced every year we've been here (5-6 years), including this time. He was here for 25 mins yesterday. When you say a full service, do you mean the routine annual service or something else?

 

[Last Plumber]

Yeah, it's been serviced every year we've been here (5-6 years), including this time. He was here for 25 mins yesterday. When you say a full service, do you mean the routine annual service or something else?

It takes me around an hour to service a boiler (basic job). If I were to do a full service e.g. remove the burner, replace electrodes, clean heat exchanger on top of the basic service, it would take me 1 1/2 to 2 hours. There would be parts involved, such as gaskets, electrodes, ionisation probes etc.

I like to keep things in good condition so the annual service is a time to make sure all's well and working as it should be, hence the time taken.
The general view these days seems to be, flue gas test, clean trap, if it's working it's fine. I think it stems from the life expectancy given by manufacturers i.e. if it lasts 10 years it's done! For that reason, I can't blame Engineers for checking the basics and calling it a do.