Oil Boiler - High Carbon Monoxide Readings

[WHPES]

I'm getting high CO readings from a customer's oil boiler, typically 250ppm

Obviously problems with aiflow, worn nozzle, poor baffle cover seal, and flue problems are what one would expect, however are there any other possible causes I am missing?

And yes....I did tell the customer not to use it and I disabled it before leaving.

 

[Dotty]

Oil pressure? And check the filter too.

 

[dontknowitall]

I messed up my FGA a week or two ago and it was reading 635ppm CO .... outside!! Luckily a couple of days later it sorted itself out.

This started because I was having high CO readings after a service - smoke was sort of okay and in went the FGA. After an hour the F wasn't standing for flue ... but French

It took me another hour or so to establish the new nozzle was faulty. So next time my CO2 is sort of okay but CO is high, I'm changing the nozzle.

 

[WHPES]

Stuffed a rag in the flue, put a couple of smoke pellets in the chamber and set the fan running. The internal part of the balanced flue spewed smoke out along its entirety like a sieve.