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.