Alpha Range boiler/cooker problem with CO2 level

bobneedshelp

I have an oil boiler/cooker (bit like and AGA) that was locking out- the pump and motor has been replaced and a new nozzle as well- All the baffles have been cleaned. It was last serviced 18 months ago and the readings then were 11.2% CO2 - 61ppm CO , 5.82% O2 at a stack temperature of 190 C - excess air 38.5% .The burner is an ecoflam minor 1 from 2003.
It has a dial on the side which controls air intake - the specs say it should be 5.5 out of 8 -
However before the work its set at just above 4 which obtained the readings above.

When I test the flue gases afterwards I cannot get the CO2 anywhere near 11% without going high on the CO The best I got was about 10.5% and this was with the air dial down to 2 . I am at 8.77% CO2 , 49 ppm CO , 9.1% O2 - its at 76.5% excess air. The measurements are taken from a sampling hole near the hotplate with the air dial at 4

Any idea what might be the issue - i had hoped cleaning it all out might improve it. The only other thing is get the chimney cleaned. I'm using a Testo 327-1 flue gas analyser

Jamie Hall

I would prioritize smoke and CO (not CO2!) when you are adjusting the air. High CO is too little air. Also you may have a flame impingement as well. Do check the flue...

bobneedshelp

Thanks - I've booked a sweep when that's done I'll take a look at the burner again if no improvement

STEVEusaPA

Are you sure you're not underfired?
Pictures and make/model number would help so we can look it up.

bobneedshelp

The pump is set to 100psi and the nozzle is as the spec. I doubt the flue has been cleaned in years - The measurement point is a hole just next to the rear of the hot plate - (remove an screw and stick in probe)

bobneedshelp

Better picture of the door info and a picture of the air adjustment.

I am going to take it out again tomorrow and check the electrodes make sure they are in alignment etc .

bobneedshelp

Its an Alpha 80 range cooker/boiler - made about 2003 the company is now obsolete - taken over by Aga ovens
The burner is an Ecoflam Minor 1 manufactured about 2002/2003

STEVEusaPA

Electrode alignment wouldn't have anything to do with poor combustion.
Air set at 4 before you were 38.5% excess air, now at 4 you have 76.5%. BTW the air looks to be set at 4.75
I'm a little confused by your first post.
Was it locking out, baffles cleaned 18 mos ago, parts changed combustion fine, or everything was fine 18 months ago, started locking out and parts started getting changed?
You also make it sound like someone else had it cleaned tuned 18 mos. ago and now you worked on it this time?
I'd double check that nozzle to make sure .75X80H (hollow, not solid).

Is this the manual for your burner?

bobneedshelp

Hi - The boiler was last serviced 18 months ago and the original readings came from that service, The boiler developed a fault (lockout) - This happened after an oil delivery and somebody switching the boiler on too soon after delivery.

Anyway I changed the filter by the tank - very dirty, changed the pump filter danfoss bfp11/r3 and bled the oil pipe to get rid of air - This didn't resolve the intermittent lockout.
The motor was making a whirring sound prior to lockout- I checked the charge capacitor and that was below spec so I changed that but it made no difference. I decided that a full service was necessary so I checked the motor and pump - They are all original (2003) so decided to change both the pump and the motor. I also replaced the nozzle with a brand new one. This solved the problem and no more lockouts. I felt it was a defective pump. The pump pressure was checked and set at 100psi - same as the original and also as per the spec. All running fine. However I couldn't get the CO2 to anywhere near 11-12% - I decided that the baffles and boiler etc need a good clean out - I have done this - it wasn't too bad but still no luck with the Flue gas readings. I then thought maybe the air adjuster had been put in wrong but I checked and it's fine. The picture was taken prior to any work so the reading on the air adjuster is 4.75 When I took readings with it at this set point it was nowhere near the 11.5%. The burner sounds good and is running well - there is no smoke either from the chimney or the flue gas test point.

I wanted to check the flue gas readings from the cooker burner and compare these to the readings 18 months ago. If I got similar readings this would should that there is something different with the boiler burner. However the cooker burner has locked out now - I did a quick bleed but no change - I think it is crudded up with stuff. I am waiting for a filter for the pump and then I will change that and bleed that pump. Take a reading and see what the cooker burner says.

Whilst lying awake this morning I did think maybe the flexible oil line might be kinked and there is an oil flow restriction so that's next to try but by the sound of the boiler it all sounds good. The flue is not getting cleaned til next week so I will keep thinking and reading.

The manual above is not the correct one - You won't find it available anywhere - I do have one though that is scanned to pdf I only scanned the relevant pages - There is more about location requirements etc which i don't need.

I will do some more tests today and record the readings with the air at different settings to see if anything becomes relevant.
I will recheck the nozzle and make sure its the correct one. I ordered the correct one but you never know.

thanks for reading

bobneedshelp

I did some flue gas testing at different settings and these are the results - I have reordered them slightly so they start at 5 and go down which is why the flue gas temperature is slightly different in order. There is no smoke at setting 4 or when the setting is down to 2.5 - tested with a smoke pump and also visual from the chimney outside.

STEVEusaPA

I think you replaced a lot of parts for nothing.
The problem I have with trying to help you is that I don't see any information on troubleshooting the electrical/electronic components, so therefore it's hard to determine why you are experiencing the lockout.

Now as far as combustion testing, usually when numbers are drastically different, it sometimes points to combustion air delivery thru the nozzle assembly and what's going on in the chamber.

If you're sure its the proper nozzle/angle/spray pattern, and proper pump pressure, next is to look at proper re installation of gaskets and components. Anything leaking air will hurt your combustion numbers. Notice your excess air numbers doubled at the same air setting.

Dirty blower wheel causes you to add more air to the combustion.

Can't tell if there's a setting to adjust the nozzle and/or end cone. On conventional burners, nozzle in or out 1/4" has a major impact on combustion.
Sometimes you just replace the nozzle again, could be bad out of the box.
And not to be a putz, but all the combustion numbers are all in line until you started messing with it. So probably whoever worked on it before can check and make sure everything is restored to how it was set up, and go from there.

Also with smoke testing, don't make the mistake of pumping it like a bicycle pump, 10 times quickly.
3 seconds on the pull stroke, 3 seconds hold, 1 second return, 1 second pause...10 times.

bobneedshelp

The Boiler runs fine now no more lockouts replacing the pump fixed it - it was just the Flue gases that were causing mean concern . I will recheck all the gaskets and and give the blower wheel a good clean . The blast tube and nozzle worth another look i will check the distance, the Ecoflam manuals have distance info -
I think it might be more to do with the air adjustment - its basically a metal mesh with an aluminum strip which covers the mesh allowing more or less air in etc. I may have moved the strip to the wrong part of the rim- when taking it apart - I do remember the wheel was quite dusty - I did mean to give it more of a clean but forgot.

Thanks for the pump info I was quite slow doing it but I will be stricter and follow your instructions.

I might move the dial to 2 and see where the CO2 goes - I might be relying too much on the dial numbers.
Thanks for your thoughts - I will see where all this takes me -

bobneedshelp

Air adjusted now and the following readings obtained
CO2 - 11.4% , CO 12ppm , O2 - 5.8%, Excess Air 38.3% - I've kept it at this level - no smoke - what does concern me is the CO level is very low.

STEVEusaPA

Looks good to me. Bump up the air a little to see how it affects the numbers and to give you a little cushion.

bobneedshelp

will do

bburd

The CO level *should* be very low. Your CO2 looks good.