Combustion Efficiency - Gas Boiler

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Old 01-02-14, 08:32 PM
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Combustion Efficiency - Gas Boiler

Hi all.

Have a Burnham Series 2 boiler AFUE is 84%. Did a combustion test today and the results are below.

O2 - 8.3
C2 - 7.1
Combustion Efficiency - 80.2
CO - 0
CF - 0
Stack temp - 385
Excess Air -59
Draft = -0.04

Anyone have any thoughts? I attached some pics of the boiler, its omly 6 years old.

Also, house was having some construction done on first floor, so there is a hole in the sub floor (about 12"x12") Seems when the unit is running there is an odor that is finding its way up to the first floor through the hole in the floor. Can't really tell if its flue gas.
 
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Old 01-03-14, 12:19 AM
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Thoughts?

Yes, every IO&M says this with good reason:

Do not alter boiler draft hood or place any obstruction or non-approved damper in the breeching or vent system. Flue gas spillage can occur.

A. Install draft hood without modification on outlet of flue collector.
For Boiler Model 204, 5" diameter draft hood: lower edge of the draft hood skirt to top of jacket
must measure 9-1/8" (Figure 1: Line Drawing Table: column F )

B. Install blocked vent switch to lower edge of the draft hood skirt.

C. Install vent damper
Mount the vent damper assembly after the draft hood, as close to the draft hood as practicable without modification to the draft hood or vent damper. [Shaft must be horizontal]
For electronic ignition insert plug in vent damper blade knockout, if missing.
Remove plug/knockout for standing pilot.

http://cdn.usboiler.net/products/boi.../Series2IO.pdf

http://cdn.usboiler.net/products/boi...ets/manual.pdf


Retest and include air temperature (at burner inlet.)
 
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Old 01-03-14, 05:09 AM
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What is " CF " in the test results above?

Why is the flue damper disconnected and hanging there?

That flue pipe installation needs to be corrected.
 
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Old 01-03-14, 12:08 PM
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CF is Carbon Monoxide content referenced to a percentage of O2 (ppm)

Also, I put back the duct work like it should have been. Pic is attached.

What I think is happening is fumes are leaking out of the bottom of the draft hood, but I can't tell 100%. Lit some paper and put it out, seems to pull smoke up ok. Also, whats interesting is the damper closes and stays closed right away after fire goes out. Guess there is no delay to let excess fumes go out.

So and suggestions? Also any suggestions on the combustion efficiency numbers. Can it really be zero for carbon monoxide.

I also stuck the meter in the hot water heater and it read zero for carbon monoxide.

Then lit a match blew it out and let the meter such in the smoke, it did actually register carbon monoxide. So guess it works
 
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Old 01-03-14, 02:05 PM
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Pic is attached.
Think ya forgot....................

whats interesting is the damper closes and stays closed right away after fire goes out.
What's the make/model of the damper? I think there should be a delay...
 
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Old 01-03-14, 02:11 PM
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When was the last time your analyzer was calibrated?
 
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Old 01-03-14, 03:16 PM
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Pic uploaded. Meter calibrated a year ago.

Im starting to think the draft is not good.
 
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Old 01-03-14, 03:26 PM
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You stated the draft is -0.04. That is a good draft. When are you smelling the fumes? While running or after shut down?
 

Last edited by NJT; 01-04-14 at 08:04 AM.
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Old 01-03-14, 06:02 PM
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Rbeck, when firmest??? You mean when does it stay at a number constant without moving around?

By the way guys house the ductwork look? Its at an angle going to the chimney.
 
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Old 01-04-14, 01:41 AM
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firmest
I think rbeck meant 'Fumes.'

By the way guys house the ductwork look? Its at an angle going to the chimney.
That could make cold vent spilling worse but before I get too theoretical please check that your damper is not included on the recall list Effikal RVGP-PC Gas Vent Damper -

Gas Vent Dampers Recalled by Effikal Due to Carbon Monoxide Hazard | CPSC.gov
 
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Old 01-04-14, 08:06 AM
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It looks like the water heater vent is tied into the boiler flue pipe...

How is that connected in?
 
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Old 01-06-14, 07:44 PM
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Seem to smell fumes while running. Kinda tough to say.

Also not sure how the combustion numbers are. Do they look ok?

The hot water heater is tied into the chimney separate. Basicall to the left of the boiler vent in the pic, and below it.
 
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Old 01-06-14, 08:36 PM
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Heatworm,

Understand the recall you sent. Good info, when I get home i'll check and see if I have that model. But as I see it, aside from needing to replace it if it is part of the recall, mine operates open and close fine right now. So, don't think its the problem.
 
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Old 01-07-14, 06:16 AM
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Is that boiler spark or pilot? If its pilot there should be a small hole, roughly 1" inside the damper to allow the gasses to escape through the chimney. If its spark, it should be plugged but it doesn't have to be. When the boiler shuts off, the damper closes which is normal, it does take a few seconds to close and that time should allow the remaining fumes to escape.
 
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