Is my burner getting too much air? (intermittent non-start / lockout)

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Old 03-06-12, 07:58 AM
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Is my burner getting too much air? (intermittent non-start / lockout)

I had an annual maintainance done last week on my oil heat boiler.

The tech from oil company handed me following print out at the end of tune up, wherein he changed oil filter, pump strainer, nozzle and vacuumed only the top chamber connecting to flue.


==== START ====
Bacharch, inc.
Fyrite Pro Analyzer

Date: 2/27/2012
Time: 10:13 am

Fuel: (F2) Oil #2

Efficiency: 83.1%
Excess Air: 41.8%
Stack Temp: 425 F
Primary Temp: 23.9 F
Delta Temp: ---- F
O2: 6.5%
CO2: 10.7%
CO: 38 ppm
CO Air Free: 55 ppm

Draft -1.81 WC

==== END ====

Since then, I have experienced daily lockouts, which typically happen in the morning and in the evening when burner trying to fire after a long period of rest.

1) Am I getting too much air here? are other parameters look right, such as CO & CO2?

The tech claimed that he is looking for excess air < 50% & stack temp < 600 F. So he left without any adjustment.

He said that the primary temp & draft reading was wrong. He tried with another meter and said the draft was -0.06 WC. (which I am not sure about the decimal piont).

The outside temperature was (mean 35 F; max 51 F; min 19 F) on that day and about 53-56 F in basement.

2) any hint about the boiler model? - I would like to get a hold of a manual to see manufacture's specification.

Boiler is Trianco with Riello Mectron M5 burner. I could not figure out the model of burner itself (no plate with boiler model). Years is probably 1980 +/- 10 years.

3) the nozzle has been .75 60W according to maintanance notes on the side of boiler. Does that seem right size?

Other details:
The house is a ranch (built in 1950s), about 2500 sq ft on the main floor. Boiler is in basement. Flue go up short vertical, and short horizontal and then into chimney (which go up basement, main floor and then through attic). total travel in chimney is probably 25ft +/- 5ft.

water is from a well, and temperature setting on boiler is currently set to 140-160 F. After burner shutdown and if there is no water follow/hot water usage in the house, I have seen water temperature in boiler risen to 180-190 F sometimes.

Boiler has 4 zones (2 main floor 2 basement) + supplying house hot water.

The burner is fed by two lines. Both the tech and myself have run motor alone (without spraying oil) so we have supposedly bleed air out of oil line.

I also cleaned photocell which did not cure intermittent non-start.


This is my first boiler and first tune-up visit. Any advice / comment / suggestion would be greatly appreciated.
 
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Old 03-06-12, 09:28 PM
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Hello Bluesilk,
I'd not be too happy with a cleaning that didn't brush down everything and vacume out the chamber afterwards. Not a very good job.
Worse yet, not checking the electrodes/gap etc.

10.8% co2 is not too bad. I doubt it is causing the start problems. My guys like to run 11%, if we try to go to 12% it sometimes ends up sooting up. I encourage 11.5 and no smoke.
The stack temps seem a bit high for that much excess air, but it's probably the nature of that old boiler, of which i know nothing about.

I'm just guessing there might be a tiny air leak in the fuel lines and air is getting sucked in causeing the bad stqarting. But i'm not really sure.

Peter
 
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Old 03-07-12, 08:53 AM
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Hello Peter,

Thanks very much for your advice and comment.

At my insistence, the oil company sent in another tech yesterday (Monday) afternoon.
He seemed to be more experienced, and addressed following:
(1) the electrodes are slightly off center and he corrected by eye. He is able to start the flame by doing this. (which he could not when first arrived)
(2) the glass of my boiler's flame observation port was blackened over the years, so the tech unbolt the whole port (metal frame and glass) to get a clear view. He exclaimed the flame was way too sparky which indicates too much air. So he adjusted the air damper on Riello/Mectron downward until he is satisfied.

Then he listened to the start-up. He told me that he now heard the flame came on as soon as fuel pump valve open - unlike previously there were a delay before his action #2. He appeared confident that my problem was fixed so he left.

The burner does appear working fine overnight. I just regret that I did not push him to re-analyze the combustion gas for me.

Back to the issue of cleaning, the original tune-up tech did brush slots above the combustion camber, but he basically pushed soot/debris into the combustion chamber, and did not vacuum the chamber at all.

What is the proper way to vacuum the chamber? Is it by removing the burner from the boiler?

Perhaps what I will try is after the burner cool off a bit, remove the flame observation port and inspect from there, and maybe try to vacuum with a shop vac from there. What do you think?

thanks again.
 
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Old 03-07-12, 09:30 AM
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What is the proper way to vacuum the chamber? Is it by removing the burner from the boiler?

Perhaps what I will try is after the burner cool off a bit, remove the flame observation port and inspect from there, and maybe try to vacuum with a shop vac from there. What do you think?
Hello Bluesilk,No combustion test.. no so good.


Not a good idea to vacume unless the shop vac is outside
Superfine soot is extremely bad for your health.

I also have a Riello, it is an F3.
My guy doesn't always remove the burner.
He takes out the electrodes and stuff from the tube and gets his hand in thru the tube with the vacume hose and reaches in and goes to work.
Every few years he takes the whole thing off and can see and get in easier.


Peter
 
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