Opinions on Co2 readings

[MarkOil]

After chatting to a few other engineers, and not returning to any of my customers for a second service yet.
I just wondered how all you other guys set your Co2 on boilers.
I was told originally to set it to MI's in the summer, and 0.3% under in the winter.
I don't think that is too bad considering I service some boilers that are not in that bad condition and when I check the Co2 it's 1-2% under the MI's!
I'm just a little concerned in the back of my mind that after serving a boiler in the height of winter, will it 'soot up' in the summer?

Thoughts and experiences would be very grateful

 

[SimonG]

I never set to mi's. I like to see it at 11 to 11.5. But i dont use an analyser.

 

[MarkOil]

You serious? Has your nose got a built in analyser? lol

 

[Killy Bing]

Do you replace the nozzle?
The high pressure "tracks" the nozzle causing more fuel to enter.
so after the year with more fuel to burn but the same amount of air, you get less co2

 

[Dotty]

Mine are set to 11-11.5% too.

Also without an analyser......

 

[SimonG]

You serious? Has your nose got a built in analyser? lol

I use an old wet kit. Nose is good, but not that good

 

[MarkOil]

So basically you always set exactly to MI's?

 

[SimonG]

Std eff boilers tend to get a nozzle every other year unless it needs one. The condensers get one every year. Had issues trying to get two years out of them.

 

[SimonG]

So basically you always set exactly to MI's?

No. Some mi's ask for 12 or 12.5. Just asking for trouble. A lot of high exposed areas round my way. When i was being shown the mysteries of oil i was told in exposed areas to give it an extra 5 psi on the fuel and set between 11 and 11.5.

 

[Best]

The "wet & dry" old fashioned way is fine for setting an oil boiler, but no proof of settings.
Just need smoke pump, "egg timer" co2 tester & a gauge thermometer.
Don't try to match MIs.
Some are wrong & can even be bettered, but often you need the co2 at less than 12%.
I tend to set the co2 as high as possible on conventional tall flues, but lower co2 on low level flues.

 

[Best]

Do you replace the nozzle?
The high pressure "tracks" the nozzle causing more fuel to enter.
so after the year with more fuel to burn but the same amount of air, you get less co2

Should be the opposite effect - more oil volume means less air to oil ratio & therefore higher co2 & potentially higher efficiency if nozzle is still okay & co2 doesn't go too high & boiler gets overly sooty.
Personally, I don't think nozzles need changed every year, unless they are coated in dirt or nozzle filter gets dirty.

 

[Ermintrude]

? More oil same air = co and less co2 thus super sutty

 

[Killy Bing]

Should be the opposite effect - more oil volume means less air to oil ratio & therefore higher co2 & potentially higher efficiency if nozzle is still okay & co2 doesn't go too high & boiler gets overly sooty.
Personally, I don't think nozzles need changed every year, unless they are coated in dirt or nozzle filter gets dirty.

Im thinking more co less co2?

 

[MarkOil]

Well this is interesting, I tend to change nozzles every year regardless, if I didn't I would be paranoid muck from the cleaning process could of settled on the tip.
I think from this I shall probably stay as I am, been servicing these boilers a while now, and not had any problems so far, just wait until the second services to find out how they did.
At least I will now know the previous service history as I seem to visit a lot that have been looked after by bodge it a leggits, or no-one!

 

[Best]

Im thinking more co less co2?

More oil means really you have a reduced air to oil mix & will mean the co2 rises.