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Discuss what could the symptoms be for a high Co/Co2 ratio? in the Gas Safe Register Forum - Public Forum area at

  1. Neddy1984

    Neddy1984 Guest

    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 :)
  2. Billy Bob Bob

    Billy Bob Bob Guest

    what boiler? on most SE appliances gas pressures being over set would be my first check
  3. Neddy1984

    Neddy1984 Guest

    I tend to find Worcesters and Vaillants have higher ratios, whereas MAIN's and Ideal are quiet low, often 0.0001.
  4. hammers4spanner

    hammers4spanner Plumber GSR

    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
  5. Neddy1984

    Neddy1984 Guest

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

    Also Gas Man, what are SE appliances??
  6. Billy Bob Bob

    Billy Bob Bob Guest

    standard efficiency
  7. villa_tom

    villa_tom Plumber GSR

    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.
  8. Dotty

    Dotty Guest

    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!
  9. Blake

    Blake Plumber GSR

    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.
  10. glenno1

    glenno1 Guest

    First thing to check fga working and been calibrated
  11. AWheating

    AWheating Trusted Plumber GSR

    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.
  12. arran197

    arran197 GSR

    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.
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Users found this page by searching for:

  1. high co reading on gas boiler

  2. reasons for getting high CO readings from a gas analyser

  • Users found this page by searching for:

    1. high co reading on gas boiler

    2. reasons for getting high CO readings from a gas analyser