combustion ratio?

[mkflow]

hi need some advice as getting bit confused.
action point for combustion ratio for a combi not condensing is 0.008
what is the action point for a condensing boiler as have read 0.008 is I.D and 0.004 is A.R is the right????


many thanks

 

[mfgs]

MI's dictate. Worcester for example state 0.0020 for a ratio, if there is no specific readings in the manuals then go off the generic guidelines. Anything over would be AR. If for example the inner flue had perished and was causing vitiation to give a high reading on a boiler it would be ID.

 

[GrahamM]

An unsatisfactory combustion reading on a room sealed boiler is only ever going to be 'AR'. Only if these POC's were to enter the room would it be 'ID'.
The MI's are required to confirm the ratio action points for a condensing appliance as most also dictate CO² limits. The Ideal HE boilers specify ratio of 0.004 and Worcester 0.002. So MI's are definitely required to confirm these limits.

The general limits for a standard eff. room sealed boiler are 0.004 or 0.008 after strip clean.

 

[Billy Bob Bob]

in the case of a performa 30 he,baxi dont want you to do a fga the boiler will never be in any spec,duotecs are 0.004 or under

 

[CMairiD]

Have a read of TB 126. GSR recommends that boilers with air/gas ratio valves and manufactured by members of HHIC are classified as:

Exceeds .008 = ID
Exceeds .004 but not exceeds .008, or exceeds manu's guidance = AR

This TB has been around for a while and it's a bit of a shame they've never incorporated the guidance into Unsafe Sits.

 

[CMairiD]

in the case of a performa 30 he,baxi dont want you to do a fga the boiler will never be in any spec

Why don't they want you FGA'ing the boiler?

 

[Billy Bob Bob]

Why don't they want you FGA'ing the boiler?

because it will give a massively high reading they are saying just to check burner pressures,this only affects 30kw band b appliances

 

[CMairiD]

That seems a bit odd! So do they typically exceed .008?

 

[Billy Bob Bob]

That seems a bit odd! So do they typically exceed .008?

yes,its to do with the resistance trough the recuperator oddly the 24kw does give a good reading typically 0.002 flat out on dhw

 

[gaspastemania]

Is anyone getting higher readings on worcesters lately??

 

[Billy Bob Bob]

never found a greenstar in spec

 

[mfgs]

I have found very few outside spec, and I have serviced hundreds.

 

[CMairiD]

We have a few hundred of these. I've seen a couple pushing year 3-4 to be slightly out on the CO/CO2 ratio.

 

[Billy Bob Bob]

most of the ones i see are between 3-4 year old

 

[AWheating]

Is anyone getting higher readings on worcesters lately??

had heard of co ppm readings being quite high on worcesters, even when newly installed? not seen it myself, but i dont test many.