Old Kewanee/Massive CO/Draft problem(SE)

Steve Ebels

Here goes:
Thursday 9:30pm I get a call from a upset apartment owner. The local service company in his town has red tagged the old boiler in his big old house converted to 4 units. Says they don't know what's wrong but it's making CO in the house. They say they will clean it for $2,000+ but won't gaurantee any thing will work. Owner informs me that he has purchased 9 electric heaters and electric blankets for the tenants and temp in the building is approaching 45*. I still had 2 service calls to go so we made arrangements to meet there 1st thing Friday.

Friday 8:30 AM we meet in the basement and I find an old gravity hot water system with standing iron connected to a huge Kewanee boiler, coal stoker, converted to oil, converted to natural gas in 1971 from the date on the burner. The owner had fired up the boiler at 8:00AM and the smell of partial combustion is everywhere in the basement. The Testo says ambient CO is at 41ppm and climbing so we ventilate in order to work down there. The Kewanee has a 16" tall by 28" wide cleanout door that is stuck shut. After some work with a pipe wrench and liberal use of WD-40 and Rustbuster, the door opens to reveal that the flue passages are completely plugged. The passages are 3" diameter tubes that run through the water jacket. I had a full day of work already scheduled so I asked the owner if he had a good respirator and a lot of shop-vac bags. Long story short, he did and cleaned it himself. The old flue scrapper was hanging right on the wall behind the boiler. He didn't know what it was or what it was for.

Friday 10:25 PM Arrived back at the apartment and fired the old girl up. After running for an hour the water temp was only up to 95* and water was pouring out of the cleanout door. I told the owner i would be back in the morning with some gasket material for the door and shut it back off at about quarter to 12.

Saturday 9AM. I lit the boiler back up after installing a new rope gasket in the C/O door and left to run another call. All the tenants had been moved to other buildings so I propped the exterior basement entry door open to provide ventilation in case of CO. This was a good thing! Came back at 11:00AM and found over 50ppm in the basement with the door wide open. A flue measurement pegged the Testo at 4500ppm CO. Condensate was raining from every crevice on the boiler. I had to laugh at the efficiency reading on that dinosaur, it was 89%+. The water temp was still below 100 so I let it run for another 2 hours and came back at 2PM. Water temp was now 115* and no more condensate was apparent. An ambient test showed 0ppm began a combustion test. This still showed over 200 ppm in the flue with all the other reading at or nearly normal. Draft was .02 wc", CO2 was 9.2%, a little high, O2 was 3.9%, a little low. I dialed up the air shutter on the Economite and the O2 and CO2 settled into a normal range but still had CO of over 175ppm in the flue before the open draft tee (10"). I decided to experiment with what Timmie has been talking about and after measureing temps before and after the draft tee found that dilution air was running about 80%. Using duct tape I began restricting the opening on the draft tee while watching the CO reading on the Testo. When I got the opening nearly halfway blocked off the CO was reading 3-4ppm in the flue. WOW! it works Timmie!! The draft was still reading -.02wc" only it was being pulled through the old boiler instead of the draft tee. Flue temp came up to 286* from 205* with the water temp at 115*. (No condensation at this water temp. I don't know how that is possible) Any way after all was said and done with a barometric installed, these are the readings.

CO in the flue 0-1 ppm

CO2 8.9%

O2 5.0%

excess air 31%

efficiency 84.6%

Flue temp 294*

Stack temp 186*

Draft in flue -.02wc

Draft in stack -.02wc"

I learned a lot on this one thanks to the discussion about barometric vs draft hoods. I don't understand how this old girl can run at those water temps without making condensation. Also I have to take some pics of funky cast iron 3" tees that allow the supply and return from the rads to exit and enter the main at the same point. Maybe someone can tell me what they are. The look like they must work like a giant monoflow tee for a gravity system. This one was fun. The owner thinks I walk on water and the tenants are in love with me (maybe not a good thing). I really enjoy making an old system work after someone else has thrown in the towel on it.

Unknown

Fantastic Steve now

try this if you can get away with it. Put a barometric in and get rid of the draft hood altogether. Because it is a conversion burner you have more flexibility as Midco (Economite) allows the use of barometrics with their burner.

But if not then I would make the covering more permanant than duct tape and secure it in place with sheet metal screws.

rudy_2

4 paragraph down

Hi Tim, reread the end of Steve's 4 paragraph down, looks like he did put a baro on.

Sounds like it's working like a champ.

The beauty of doing this on an old coal conversion unit is that it was never designed with a draft hood or baro. When it was retrofitted to gas, all that was required was 'some source of dilution air'.

As such, there's absolutely no problem putting on a baro.

Makes combustion analysis alot of fun, doesn't it Steve!!??

Unknown

Thanks Rudy sometimes I think

I am getting old and do not see things I should.

My wife tells me all the time that I do not listen, now she can add I do not read. She and I have already decided I do not hear well (that has been going on for years).

Thanks again

rudy_2

Yep

You and me both, buddy!!!

Like the saying goes:

"God grant me the senility to forget the people I never liked anyway, the good fortune to run into the ones I do, and the eyesight to tell the difference."

Dale

Old conversions

With an economite or other power burner you often need to reduce the size of the vent pipe and or reduce with a sheet metal guilotine (SP). Also called a neutral pressure point slide. The old coal units often had a larger vent then needed for gas. Timmie could probably speak to this better than I can as I was only in for the tail end of the massive oil to gas conversions. This reduces the excess air. The sheet metal slide is put in the vent between the flue collar and the draft diverter and pushed in until the CO2 was about 9%. If the pipe gets replaced without the slide gate put back in you get really high stack temp. The old bacharach bulletin 4006 "Gas burner combustion testing" showed this application. If you email me with your PO address I'll send you a copy.

Unknown

Dale the only thing I do different

is to cut the adjuster in between the draft hood and the chimney so that the total draft can be adjusted. Tom Roche an engineer who owned T.C. Roche Associates and was a major distributor for MIDCO up until he retired several years back taught me that one. He was affectionately known by most of New England, New York, PA and NJ as "MR. Combustion".

It is amazing the affect it has on total draft and high stack temperatures.

Steamhead

Nice Job, Steve

sounds to me like that old Kewanee just got a new lease on life.

You are correct, it's an old "one-pipe gravity system" which was the predecessor to Monoflo. When it comes time to change that boiler, use a VERY small circulator on it to mimic the gravity flow.

Can't wait to see your pics!

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Mark Eatherton1

Not sure but...

I think its called an OS fitting, which stands for Oliver Schlemmer if memorie serves me correctly...

ME

Mark Hunt

Excellent


The best gather here folks!!!

It isn't always in a book.

Mark H

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rudy_2

Apparently..

> I think its called an OS fitting, which stands

> for Oliver Schlemmer if memorie serves me

> correctly...

>

> ME

Steve Ebels

O Guru of Btu's

Tell me why this old dog doesn't make any condensate at 115* water temp? I opened up that cleanout door with it running to check for moisture and it was as dry as a Death Valley bone in there. Is condensate just a function of exhaust gas temp alone? In other words, the water temp makes no difference as long as the exhaust gas is above the dewpoint of the fuel?

rudy_2

Apparently...

Mark, apparently, your buddy Oliver is one of 'Dan's dead men' and was also involved with the 'Spence' Hot Water Heater (circa 1890). Take a look at this ad I found:

http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=/moa/scri/scri0007/&tif=00848.TIF&cite=http://cdl.library.cornell.edu/cgi-bin/moa/moa-cgi?notisid=AFR7379-0007-79

If any of you haven't seen the Cornell University "Making of America" site, it is way cool. They scanned thousands and thousands of articles from tech journals written between 1815 and 1926. They take awhile to download but fasinating stuff.

Here's another I found on the advantages of steam heat:

http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=/moa/manu/manu0002/&tif=00246.TIF&cite=http://cdl.library.cornell.edu/cgi-bin/moa/moa-cgi?notisid=ABS1821-0002-510

"On pages... we have explained some of the drawbacks in the use of iron stoves; how they deteriorate the air which comes in contact with their hot surface, and the injurious effect upon the health of persons who inhale this air, scorched as it often is during its passage along the red-hot surface of cast or sheet-iron."

Go to the search engine and type in just about any topic, its amazing what comes up - I've spent a bucket load of hours at this web site!!

Mark Eatherton1

Dew point explained...

Steve, the dew point is a direct function of relative humidty, which is directly related to air temperature.

When it is colder outside, the dew point is much lower than if it were warm outside. Here's an explanation.

http://www.easteagles.com/hum_dewpoint.html

Keep up the great work! It does make your chest puff up when you fix something everyone else walked away from...Rightfully so.

ME

Mark Eatherton1

Cool!!

Thanks Rudy. I saved that place as a favorite. Maybe Spence was Ollies son???

ME

tim smith_2

stack temps

your stack temps are too low, that boiler will always condense on start up for quite awhile at those temps. I think you need to raise your input and re-adjust burner. Get your stack temp up to 300 after a few minutes from dead cold fire up. Then as boiler approaches set point you will have appx. 360 degree stack which will minimize or stop condensing in fire tubes. Other wise corrosion and block up will occurr. Tim

Mark J Strawcutter

Could also be

Don't think OS fittings allow supply/return from common point on main.

The fittings could also be Eureka or Phelps.

Mark

PS - pics borrowed from "gravity" section of Q&A here at heatinghelp.com

jim sokolovic

Draft effect...

quite the coincidence that this job came up in the middle of Timmie's post - it helped confirm the fix he detailed for all of us. Steve says the readings all changed except for the draft, which didn't seem to be that unusual in the first place. Can we get from this that testing the draft reading alone (as changes are made to lower the CO) does not correlate to any indication that the situation is improved? This job being a burner conversion type, I understand the need to fiddle with the venting setup in the field. It still bothers me to learn that on other jobs, a boiler that is factory tested and supplied with integral burners and a designed draft hood would require this type of alteration. There is no arguement here, only true concern.

rudy_2

You are absolutely correct Jim

All draft testing does is measures the pressure difference between the inside of the vent system and where the guage itself is located.

Combustion testing verifies that:

-The flue gases are being drawn through the equipment and vent system as designed and,

- at a sufficient rate to allow for additional (and proper) combustion air intake.

The 'Captain' explained this to me years ago and really helped me understand what was going on and how to properly diagnose the equipment 'as a system'.

I'm thrilled to see your concern Jim. I think the main problem is that testing in a lab does not necessarily reflect what goes on when the equipment is put in a building with it's own 'personality' and a alot of variables that just can't be accounted for.

A fixed draft hood simply does not have the versitility (like a barometric) to adapt to constantly changing conditions, particularly in a chimney.

Steamhead

You're right, Mark

O/S fittings were used on risers rather than mains. But their purpose was similar- to split the flow so each radiator got the water it needed.

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tombig

Eccentric tees

I've seen a couple of gravity one pipe water systems that used standard tees for the rad supplies and eccentric off the bottom for return. Pre-monoflow they they worked like a champ. Piped to 2nd and 3rd fl. rads too! Everyone wants to over pump these guys after seeing the 3 or 4 in. mains! Low flow rates will make these systems honor their designers.

Steve Ebels

I don't think it can be done

With as much mass as there is involved with this old system I doubt very much if you could reach a stack temp like that within 8 hours of start up. The burner is rated for a maximum of 190,000 btu's and that's right about where it is according to a quick meter clocking. There are probably 3-4 tons of iron plus piping and the water itself that all had to be brought up to temp. Bear in mind that the system water temp was in the low 50* range when I first started it up and only 115* at the time of testing. If I get a chance tomorrow I'm going back with a camera and check it again with more normal water temps. It's only 3 degrees right now and dropping so the old girl should be at a full trot tomorrow.

Thanks for the advice and concern. It's understood.

Mark Eatherton1

I have seen...

horizontal one pipe fittings with the initial OS on them.

Got a picture around here somewhere...

ME

tim smith_2

Burner size???

Steve, then the burner is probably too small for the old Kewannee. You can look up the size of boiler and see what it was rated for. If the burner is only 190mbh, i think it's undersized for the boiler. I don't recall seeing a Kewanee firetube that was rated that low. Just looking at the combustion #s it does not sound right. Tim. PS: I also re checked you 1st post and at 115 degree water I guess it's not the worst but still would be concerned about too much condensing in chimney and also boiler on start up.

Steve Ebels

From the original data tag

Manual firing rate 180,000 btu

Stoker firing rate 187,000 btu

BTW at 6 degree outdoor temp the boiler water is still only 122*

Steve Ebels

Pics, (I hope)

Here are some pics of those "monoflo" gravity fittings. All I can make out on the fittings is Hall Iron Co. Chicago Ill. Water flow enters at the narrow end of the fitting and returns into the bulge which seems to cause the water to flow around some sort of internal restriction in the fitting and back into the loop through the bottom of the fitting. The whole thing is a single pipe setup a lot like primary secondary only with the normal supplies and return spaced about 4 feet apart. There are 6 radiators that are fed though these funky fittings. You can see the heat exchanger in some of the pics with the cleanout door open. The bottom row of tubes extends half way back over the firebox and the top row goeas from the front through to the flue collector on the back of the boiler.

Steve Ebels

I

give up.

Mark Eatherton1

Steve,

try saving them down to a file as JPEG files. You may have to open it up and save them individually with the soaftware for the camera.

Look forward to seeing them.

ME

Steve Ebels

try again

N.M.