Chimney with Internal Steel Beams

Mike11

Has anyone ever come across an existing masonry chimney that is within the foot print of a building and has large steel beams spanning the width of the chimney at each floor? The chimney is about 120-feet tall and the building has 9 floors. Based on a chimney inspection, the beams appear to be 8-inch or 10-inch channel and occur at each floor. The beams are staggered and would make the installation of a liner impossible unless they are removed. The liner would be needed if we decide to switch to natural gas.

icesailor

Are the beams inside the flue ways? or are the chimney flues just offset around the beams?

They're "Channel Iron" beams and not "I" Beams?

nicholas bonham-carter

What type of boiler/system is in the building now?
How big is the chimney? What size flue is needed for the boiler?
Are the ends of the beams extending through the chimney walls into the floor structure. How have they been effected so far by flue gasses?
What a challenge!--NBC

Mike11

The beams are inside the chimney, they are C -channel and not I-beams. The inspection revealed that the beams are covered in soot, however they appear to be intact.
We are going to perform a probe at various floors to determine if they are attached to the floor structure and ultimately determine if they are structural beams.
The chimney is 26"x26" square.
The boiler is 80HP and has a 15" diameter breeching. It is likely that a 15" liner would be required if we are to convert to gas.
I'm just wondering if anyone has ever come across this before.
The steam system is a John Mills downfeed type and the riser is a 5" pipe that runs in the chimney to the top of the building. I'm sure that steam is superheated by the time it gets to the top.

icesailor

This is a slanted chimney?
When laying bricks and blocks, their full vertical compressive strength doesn't become completed until the mortar is set. Look at arched roman bridges or modern bridges. Arched brick coursed over round windows. Mason's build a form to lay the bricks to when they build the arch. Once done, the form is removed.

The beams were probably there to set the wet mortared bricks or blocks against when the chimney was being built. The "beams" almost sound by your description like headers. Before they ruled that chimney's were supposed to stand alone. I'm surprised they ran them through the actual flue way. I'd really be surprised if the brick mortar wasn't pulled away and separated where the beams start entering the chimney from building expansion and contraction. Allowing an air leak into the flue way.

nicholas bonham-carter

Is a 15 inch liner large enough for 80 HP (3 mil BTU?).
Maybe putting several smaller boilers on the top floor could be an option, as an alternative to opening the can of worms!
There is already the down feed pipe in place, and all you need is a tank and pump for the condensate return.--NBC

RobG

You should talk to Tjurnlund, their engineers can usually figure out a way to direct vent just about anything.

Mike11

icesailor, you make a good point regarding the expansion and contraction of the steel beams. I'm leaning more towards your comment regarding setting wet mortar bricks or blocks against. Or possibly some type of scaffolding system when constructed.

"when chimneys were ruled to stand alone", do you know when that was approximately? The apartment building was constructed around 1900.

The chimney is not slanted, it runs straight up within the footprint of the building.

SWEI

You might want to consult a structural engineer. I've seen steel in chimneys used to provide midspan support to floor joists.

Mike11

Yes, we have a structural engineer on board and he will be performing a probe at various floors to see how the steel is connected to the structure.

I'm hoping it is not structural.

icesailor

SWEI said:

You might want to consult a structural engineer. I've seen steel in chimneys used to provide midspan support to floor joists.

They did that often. But they put the beams into pockets. They didn't run through the flueway. It was common back when/then to catch beams by corbeling out an inch or so beyond the straight run to catch the beam and transfer the load onto the chimney. Each course corbelled out an inch or so, so you needed 6 or less coursed to provide support for the beam.

Don't do this with wood framing. Not because wood might catch on fore, but because wood structures shrink as they dry out. Steel and masonry do not. WHy the marble rolls to the middle of the room when placed on the outside walls. It isn't settling, its wood shrinkage.

Consider this.

I found a situation where a perfectly good 1963 Vintage Weil-McLain boiler in a commercial application boiler was replaced for no other reason than someone could get paid for doing it. When they changed it, they didn't read the I/O manual about not using silicone on the rubber gaskets. The boiler leaked water so badly that it could fill up the chamber with water when not being run. The rest of the time, it just made condensation. Which destroyed the clay tile flue liner. It had nothing to do with the leaking boiler or the vast amounts of white water vapor coming out of the flue in the winter. A "chimney specialist" was employed and he proclaimed that the cause was a tiny unused incinerator used to burn occasional sensitive papers. The "Expert" announced that the flue could only be repaired by re-lining with a system he sold called "Pour A Flue", used successfully in Europe. You stick a long rubber blow up tube down the flue, blow it up with air, fill around the tube with a special insulated concrete, when dry, you release the pressure, pull out the tube, and you are good to go with a nice smooth flue. The "Specialist" didn't have a tube to fit a 16" X 16" tile (14"X14" inside dimension) so the solution was to take two 8" diameter tubes together and wrap them with clear plastic shipping wrap, stick them down the chimney, and presto, a new flue. Which is now, an oblong shape of 14" one way and 8" deep. The boiler still leaked, and the chimney was now too small. A few years later, the specialist moved to Argentina. Important people decided that the boiler needed to be replaced for many unrelated reasons. Many were asked to price the boiler change. I was not one because I knew that there were problems, and I didn't want to sail with that fleet of ships.

After a while, in the fall of the year, before the boiler needed to be run, I was asked to give a quote on replacement. Which I did and was told to go ahead. When I dismantled the boiler, I found all the leaking gaskets covered with RTV Silicone. The new boiler worked fine. The Carlin 201CRD that Weil-McLain specifically specified for that boiler didn't. No matter how hard I tried, it would soot up in a few months of operation Although it was a positive draft-fired boiler, there just wasn't enough available draft. In researching out the issue, I remembered that there was only less than 8" from the back of the flue to the thimble opening. After another project, I looked up the flue through the cleanout door with a 500 watt quartz light and mirror. That white thing against the black was not the Batman symbol on a cloud, but the sky above. Sea Gulls were flying by. And I was seeing the shape of the newly reconstructed flue. The flue was fine. Just now, way too small. Tjernlund suggested a product where you put this fan assembly on top of the chimney and it "sucks" the gasses out. My answer to that was, I'll call you in a January Blizzard when it is blowing 60 and snowing. To change the dead motor on that fan, 16" above a 12" pitch slate tiled roof. I'm going up that roof with a ladder and put it against the chimney and changing that motor? I don't think so.

I remembered that you can suck up water with a vacuum practically, from 27' and theoretically from 33'. But you can pipe water to the moon if you have a pipe long enough and a pump big enough. So, I found a fan/draft assist made by Field that had a big suck end and I could connect the power/pressure end to the chimney flue. Wired it up, and it worked like a charm. No more sooting, plenty of adjustable draft, just a fine thing.

If you've read this far, a solution to your flue liner is that you can positive draft fire it and match it to whatever size you can get down the old flue.

I had another account where they built a chimney with two flues. One to handle two oil fired water heaters and three boilers, connected to the other one. When the job was done. the guys in the white hats proclaimed that the three boilers were too big for either flue and that if they took one boiler and added it to the two water heaters, then that flue was too small. What to do?

Well, there was a company in Boston who specialized in dealing with these dilemma's. They made a big flue collector that picked up the two oil fired water heaters AND the three boilers, and put it in to one of the same too small flues. All approved, legal, signed off, and running like that for over 30 years.

That's where my idea for the first story came from.

A round SS liner will be a lot tighter than that chimney with the steel running through it. IMO.

Gordy

I think your structural engineer will find that they are an intergral support to each floor. Some how the chimney is apart of the structural loading at each floor.

icesailor

And if there is an issue with a liner, see about positively pressurizing it.