what could the symptoms be for a high Co/Co2 ratio?

[Neddy1984]

Hi everyone,

I'd like to know what the common problems/symptoms could be for a higher than normal CO/Co2 ratio when using a Flue Gas Analyser. What should I be looking for i.e correct incoming gas pressure from the meter etc. Are there a few problems which you would always check first and most of the time it tends to be that one thing, or could it be many different reasons on any given job?

All your helpful answers would be much appreciated..... thanks in advance :-)

[gas man]

what boiler? on most SE appliances gas pressures being over set would be my first check

[Neddy1984]

I tend to find Worcesters and Vaillants have higher ratios, whereas MAIN's and Ideal are quiet low, often 0.0001.

[hammers4spanner]

i think alot of MI's state if you get a high reading they recommend a strip and clean then re check , could be wrong tho

[Neddy1984]

Im sure they do........ but strip and clean what exactly??

Also Gas Man, what are SE appliances??

[gas man]

im sure they do........ But strip and clean what exactly??

Also gas man, what are se appliances??

standard efficiency

[villa_tom]

Any set of manufacturers instructions will tell you what ratio you need to achieve and what to do if it's out. If you adjust the ratio at the gas valve etc and yo still can't obtain a good reading then yo have to check reasons why, ie gas pressure, flue integrity etc. if these are ok then a full strip and clean will be need, which you can find in the MI's.

[croppie]

There's a range of boilers I look after on the commercial side, Potterton condensing Derwent, which are thankfully obsolete now, I get issues with them with the fan assembly. Burner pressure on the nose, boiler sparkling inside (and out!) but dreadful fga readings, the fan loses 10-20% of speed through wear and tear. Generates enough air to activate the aps but doesn't pull the flue gases through fast enough.


Horrible boilers. A new fan is the best part of a monkey and becoming increasingly more difficult to get hold of. Every one I go to I report the thing as life expired...... Sometimes I love government work!

[Blake]

Im sure they do........ but strip and clean what exactly??

Have you done your CPA1? I only ask as this should have been explained during your training and if you are not sure what you should be cleaning in order to try and achieve the correct results you probably need to re-read all of your training notes. IMHO.

[glenno1]

First thing to check fga working and been calibrated

[AWheating]

basically it can be anything involved in the combustion process......from the gas main/meter to the flue terminal and the correct operation and use of your analyser.

[arran197]

Gas pressure is the easiest thing to start with, obviously BP and IWP on old boilers and just IWP on new ones. From there you need to be gas rating and checking the integrity of the flue. On some condensing boilers the gas valve is adjustable to get the perfect ration and co2 percentage. But you need to make sure you follow the right procedure for adjusting any gas valve. The amount of times I have come across Greenstars that have been incorrectly adjusted is not funny. Especially the older ones like the R series. Manufacturers are always glad to guide you through how to adjust the thing, just call them and ask. No one is going to knock you for getting extra information about an appliance.