The other Utica Boiler from last winter

Unknown

a Utica Boiler we had problems with high CO. I thought some of you might be interested in the final outcome.

I had a class yesterday and we did some final testing on this unit which has been running fine since we did the following:

1. Repaired and relined the chimney

2. Replaced 6 burners on the boiler which were cracked

3. Completely cleaned the boiler and did some minor repairs to air leaks.

4. Replaced the flue pipe into the chimney which was trapped originally and gave it a 2 foot rise directly off the top of the boiler.

5. We had also blocked the draft hood last year and installed a barometric. This has since been removed as the local gas utility condemened it even though we proved it worked better that way.

Readings taken yesterday with the class:

CO2 9.1%

O2 4.8%

Net stack before the diverter 550 degress

After the diverter 475 degrees

Draft before the diverter -.01

Draft after the diverter -.025

Efficiency 78%

Interesting we tested another Utica boiler in the same basement a different chimney which has had nothing done to it and the readings were almost identical.

jim sokolovic

Timmie - so why do people want to jump...

and install barometrics on jobs with integral hoods when you just proved it was the chimney that was improper? Assuming the final CO reading was low, I mean?

Unknown

Jim, the chimney repair

last year did not really stop the problem it was a combination of things we did. When I tried the barometric it was because I had done this on another Utica boiler before with a similar problem and it really helped the situation. I personally do not like draft hoods built into boilers I have had many problems with that boiler design in the past. I really prefer a draft hood after the boiler with a good flue pipe rise before the draft hood.

jim sokolovic

I remember last year's thread...

it was very interesting, given that you had 2 identical boilers at the same site - one with combustion problems, the other running fine. You felt that the chimney was suspect, but could not get it repaired right away, so went with the barometric. Did the barometric "fix" the cracked burner / leaking heat exchanger problems that you just recently replaced / repaired? Is this a good thing? Am I missing something on the overall topic?

Unknown

Yes you are missing something

or perhaps I confused things. I had the barometric in and the draft hood covered after all the repairs were made. There was a red tag on this boiler due to high CO reading. The gas company came to inspect the job after repairs and to remove the tag. they would not let me leave it so it was removed. the combustion analysis with the barometric was better than what it is now but they were not convinced. I hope that clears it up. The installing a barometric did not solve the problem it is just what I did because it is my preference with built in draft hoods to get rid of them. When I worked for the gas company (same company new personnel) they did not have a problem with this and by the way it did solve problems in the past with high CO and poor combustion. When I put them in I usually install a thermal spill switch and a special chimney cap to prevent down drafts.

jim sokolovic

Timmie, thanks for clarifying...

the sequence of events. I did not recall you mentioning any repairs/parts replacement/cleaning in last year's post. I'm just trying to understand better what you deal with in the field, and the proper actions to find and fix the problem. I am still not very comfortable with this subject - but not because of how you or a handful of technicians would make these modifications and adjustments.

MIKE6

boiler

What do you mean by air leaks?
Mike

MIKE6

Gas co

What authority do they really have?Isn't the plumbing inspector over them?
Mike

Grumpy_2

Gas Co authority

They have the power to shut it (the gas) off. That's all the power they really need.

I have noticed that in the far recesses of the gas company's upper management, someone will make a decision and all the underlings will immediately institute the policy. It doesn't matter if the policy is a bunch of bull, no matter how many times you prove it erroneous, once the order comes down from on high....it is gospel! Too bad we have to deal with sycophants and yes men that are more in fear of losing their jobs than they are interested in serving the customer's needs. Since the deregulation of the natural gas industry, it has gone straight downhill.

Unknown

In RI the gas company

is the authority as far as gas equipment goes. The plumbing inspector can okay a job but if the gas company shows up and finds something wrong they do not have to give you a meter.

If the gas is already on and they are called to service something and find a code violation they will make it inoperative and red tag it. Inoperative means they disconnect the gas line to the heating or other faulty equipment.

Unknown

Air leaks

are openings in the boiler sections allowing air to leak into the upper passages of the boiler which will give false readings on your combustion testing equipment (I call it "tramp air") and also cool the flue gases further contributing to the CO problem.

Also making sure that when all the doors are in place on the equipment no air comes in at places other than where it is supposed to.

Glenn Harrison_2

Tim, can you

elaborate on where you found these air leaks, and what exactly you did to fix them.

I've had a few troubleome twenty or so year old Utica's all of which burned HIGH CO. The one was sooted, so it got a good cleaning, had the burners replaced and the orifaces replace/downsized to clean it up (this is the one that also CO poisoned me), the other two I just turned down the gas pressure to clean them up temporarily and turned them off, because they had large cracks in the faceplate over the pilot burner.

Thanks, Glenn.

Unknown

Glenn,

I had the heating contractor take the unit completly apart and we resealed all the sections with a mixture of furnace cement and refractory cement. I was not sure where the opening had occured but it showed up on testing that the O2 readings did not make sense. After sealing everything up the CO readings dropped considerably. I also had some holes in the back decorative outside of the unit which we sealed with new sheet metal and RTV sealant. These had allowed air to come in the back of the unit and also the bottom had some holes in it which we sealed. Air leaks can really play havoc with combustion analysis.

It has been my experience with Utica and some other boilers like Enerjet which comes to mind of very high temperatures being developed during extended periods of running time. This obviously when outdoor temperatures demand heat and the boilers are probably cycling on limit. This has certainly done in thermocouples on these jobs. It is my theory that this also contributes to faceplate and decorative cover damage. I have found discoloration and scorching on the outsides of all these units. It would perhaps seem that the cause was flame roll out or something similar but I have not found that to be the case it is usually on the sides and back of the units and the faceplate being warped or having cracks. This also contributes I believe to the cracks in the pressed metal burners. This particular Utica boiler has six burners all of which had several cracks in them. This will definitely cause CO as cool air is being drawn up under those burners and into the cracks causing a reduction in flame temperature. The gas flame has to stay above 2800 degrees at all times in order to burn correctly. In fact in ideal conditions it may burn around 3200 degrees. Jim Davis may have some info on exact flame temps but off the top of my head those figures come to mind. It is a fact that when we cool (quench) the flame we have CO, or if the flame impinges on cooler surfaces we make CO and this certainly occurs when we have air leaks causing fluctuation in flame pattern.

I try to keep boilers at rated input as much as possible as I find that derating can cause CO also. Hey push come to shove maybe sometimes it is better to replace the thing.