Boiler cleaning burner setting question

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  #1  
Old 06-20-18, 09:30 AM
J
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Boiler cleaning burner setting question

Having the boiler cleaned this Friday. Weil-McLain WG04 with a QB-180 burner, and Honeywell Smart Controller. Yes, I am familiar with the QB-180 reputation. However, to date, it has not given me any problems.

The boiler was last cleaned on August 31, 2017. The nozzle that I stay with is a Delevan 1.00 70 B. The attenuating air band setting was left at 7.5. However, the cam setting was increased from 1.25 to 1.37.

What I have noticed since this cleaning (for the most part during the heating system when the system is in constant use), is that when the boiler fires, it seems to fire more roughly than in the past. The barometric dampers also seems to open and close more forcefully.

Most of the time, the rough firing will even out, but at times, it just sounds like it is firing rough throughout the cycle.

What might cause this rough firing?

Could it be the slightly higher cam setting - I don't know what the cam setting does? I've tried google it, but that did not help.

Could it be some type of back pressure since the damper is loud initially?

Any thoughts are appreciated.
 
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Old 06-20-18, 10:05 AM
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The electrodes/porcelains might be worn, only have so much adjustment with that as it was made as one piece.Cam moves assembly forward and back. Been out of it for awhile now but if I remember they were getting harder to stock even then. Could be a simple adjustment or something different, transformer etc. Good luck.
 
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Old 06-20-18, 01:22 PM
J
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Thanks for the feedback.

The electrodes were in good shape/not worn.

So would changing the cam setting from 1.25 to 1.37 move the electrodes forward, or move them backward. And with that slight movement, might that account for the rough starts/running, and the damper initially clanging?

thanks
 
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Old 06-20-18, 02:29 PM
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Here, the warning at bottom should explain.https://www.manualslib.com/manual/12...?page=7#manual
 
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Old 06-20-18, 05:44 PM
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On page 6 of that manual from guyold it will give you the recommended settings for your burner which is 1.20 for the cam setting and 5.25 for the air band.

Final adjustments for a clean burn should be made with instruments of course but it sounds like you have too much air being delivered which causes rumbling or your rough running as you call it.

If you boiler was running good at 1.25 cam setting I would put it back and check results. It is closer to the recommended settings.

Hope this helps a little.
 
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Old 06-21-18, 01:05 PM
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Thanks to both of you.

I'll update this thread after the cleaning tomorrow morning.
 
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Old 06-23-18, 11:24 AM
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Boiler cleaned yesterday. Tech kept the air band setting at 6.5 vs. 5.5 for the spec. He did set the cam setting back from 1.37, but to 1.0, not 1.2 as per the spec. He stated that with the Delevan 1.00 70 B nozzle (1 gallon/minute), that this was the correct setting to match the nozzle size.

He also agreed that the rumbling/rough sound I was hearing was due to the fact that the boiler was getting too much air during firing.

Nothing from me was going to change his mind to first try the factory specs of 5.5 for the air band and 1.2 for the cam.

On testing the system, he got .01 - .02 for the draft at the pipe on top of the boiler, not in the chamber. He stated it should be .04 - .05; that the spec was not accurate since it was under ideal testing conditions.

He stated that he felt there was a blockage in the chimney since the draft was so low, yet for the last 15 years I have had this boiler, the reading has always been between .01 and .02.

Go figure.

The CO2 tested at 12%.

The smoke test was 0, though I did not see him use a piece of white parchment paper and the device they normally use to do the smoke test, so I do not know how he came up with the 0 smoke.

Efficiency came in at 85%.

However, the system now has no rumblings; it sounds very quire with a smooth burn.

Feel free to comment on the above.

thanks
 
  #8  
Old 06-23-18, 01:58 PM
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j,
Taking things one at a time.

The air band setting. The chart is a recommended setting under ideal lab testing. Instruments should determine the best settings but without a proper smoke test there is no way he could know what the right setting was.

The same with the cam setting. You do have a 1.00 gal. nozzle but your factory set pump pressure, if not tampered with is set at 150psi instead of 100 which is what your nozzle is rated for. At 150psi you are actually firing almost 1.25 gal. an hour which is why they probably recommend the 1.2 setting but again without gauges it's impossible to tell.

Your breach draft (smoke pipe) is a little low. Looking for .03-.04. You didn't mention an over the fire draft test which is done through an opening over the burner. This will tell you if you have enough draft to pull the heat to the chimney or if you have a back draft which you do not want.

You should be able to put your hand in front of the opening without feeling the heat if you have proper negative draft. Excessive draft lowers your efficiency and not enough will create sooting which on paper gives you a higher co2 reading and can cause damage to the chamber and nozzle if the heat is bad enough.

As far as your chimney being blocked. He could have confirmed that just by putting his mirror in the smoke pipe opening in the chimney. By code your chimney must be a certain height but surrounding conditions determine the final height to draw a proper draft. Your chimney may be a little low because of high trees or higher homes built around you. A draft gauge would tell you that.

I have run into draft problems in the past and to check if chimney height was the problem I temporarily added lengths of smoke pipe to the top of the chimney until a proper draft was attained and then at least I knew how high it should be, then it would be up to the person if they wanted to address it. Code doesn't always meet the needs of the job.

What did he get for a stack temp. The temp of heat going up the chimney from the boiler which is a determining factor of your final efficiency test. Net stack and co2 give you your boiler efficiency.

Hope this helps a little.
 
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