FGA Readings - Oily question!

[SimonG]

You generally know you have a problem when you see a little diy 4mm allen key in the bottom of the boiler

 

[kimbo]

How accurate ois your analyser if you havent had it calibrated it could give you a bad reading, I always finish off by smelling the flue gases.

 

[WHPES]

High CO readings are usually caused by one or more of the following:

1) not enough air to give complete combustion (check flue and air inlet and room ventilation)
2) too much air having the effect of "blowing out" the flame (reduce air)
3) too high pump pressure putting too much fuel through
4) worn pump giving uneven spray
5) wrong, worn or faulty nozzle
6) contaminated fuel (eg with some gas oil mixed in it)
7) soot, fuel drips etc in the combustion chamber as a result of servicing or flue sweeping (leave running for an hour to burn off and take readings again)



Possible but unlikely to be the nozzle.

Check pump pressures. Maybe pump starting to wear out. Can give poor spray pattern.

If it's a conventional flue, has it been swept recently?

Check balanced flues and low level flues using a flue brush. I once found a dead bird blocking a flue pipe.

If balanced flue check that the seal between the inlet and outlet has not started to degrade and needs replacing (common problem on 1990s Triancos with BF)

As previous poster says, smell flue gases (don't inhale of course). Oily sooty smell means too rich. Harsh, acrid smell means too lean.

If the customers are keen on something newer and more efficient, then it's getting on and it's a good idea to replace.

 

[dontknowitall]

Thank you for the continued input and BIG thank you for that post, WHPES!!

That should be required learning for people like me!!

I will be returning but need to find my gauge (I'm sure I've already said this?!)

 

[WHPES]

First and foremost I'm an engineer before a boiler guy.

Many years ago when I'd not been going long, point (7) had me puzzled when I came to set up a boiler after the chimney sweep had cleaned the flue. Took me about 1/2 an hour before I realised all the soot debris in the chamber was burning off and giving me duff readings. Came back in a couple of hours when all burned off and set it up no problem.

I once found a dead rat in a combustion chamber where the customer had not run the boiler over the summer and turned it on to find smoke coming out of the flue.

 

[DirksPlumbing]

I once found a dead rat in a combustion chamber where the customer had not run the boiler over the summer and turned it on to find smoke coming out of the flue.

Must have been a big boy. Had 3 weeks ago a boiler with a dead bat in in. To wet to get it cleaned. And wasps. Stuck the burner back in and test run it for less than 30 seconds. All had turned into ashes. Just a few bone fragments you could imagine where the bat had been.

 

[WHPES]

PS to my previous post, just thought of another reason - the air diffuser / nozzle distances set incorrectly will give high CO readings again because it results in incomplete combustion.

 

[DirksPlumbing]

PS to my previous post, just thought of another reason - the air diffuser / nozzle distances set incorrectly will give high CO readings again because it results in incomplete combustion.

Jupp. But on domestic boilers that normally requires a dodgy engineer as most of them are not or not straight to set up nowadays . Still remember the old days where the distance bolt had been accessible at the back. How often these had been "screwed" with. Possibly because they had been mistaken for air settings.

Another curiosity I have not seen since many many moons are the "blue" burners.
Hated them with a vengeance. As the ceramic blast tube easily cracked by taking the burner out.

 

[yorkie]

Called out last week October to W/bosch combi that had stopped working. Listened to customer as you do and asked him to put phone to boiler and re-set as he said it was working then stopped I didnt think it was firing just the fan purging. When he did the noise was that of a broken /stuck motor. Went round next morning and under the fan casing was a big blob of goo. Open casing and found three mice totally perished and chewed up by fan. They had gone rotten and dripped all inside casing and ran out. Cleaned all out as they had jammed fan and boiler now working after good service. Lovely jobs we have.

 

[Best]

I have just posted on the thread "mouse jam" about similar thing, except fan kept running but air was partly blocked & boiler sooted up badly. All bits of fur & grease! Terrible! :smile: