How to cut up an old coal burning furnace in my basement

November 30, 2019 10:53 AM

Ancient coal burning gravity furnace. I need it gone. It's huge and weighs a ton. Far bigger than the doorway, it has to be cut into pieces to get it out. It laughs at my reciprocating saw. And there's no room to swing a sledgehammer down there. Suggestions?

My house is 130 years old. At some point, the previous owners upgraded from a fanless 1890's gravity furnace to something more efficient, but their HVAC contractor was evil/greedy and did not remove the old furnace, just shoved it into a corner, so now it's my headache.

I have already cut away the thin sheet metal outer layers, those were relatively easy. What's left (the coal pit itself) is heavy thick iron or steel. My (cordless) reciprocating saw makes essentially no progress on it.

There isn't enough room to smash it with a sledgehammer effectively, and besides I don't want to damage the new furnace it's crammed next to.

I don't know anybody with a cutting torch, and am not sure that's the best way to attack it.

Suggestions welcome.

posted by Glaurung to Home & Garden (30 answers total)

Aside from sledge-hammering or mechanical disassembly (unless it’s all one casting), the other way to cut it would be fiber-reinforced wheels on an angle grinder. A good 4.5” grinder runs <$100. The wheels won’t last long, so buy in bulk on Amazon rather than singly at your local Home Despot.
posted by jon1270 at 11:01 AM on November 30, 2019 [1 favorite]

(Wear eye protection).
posted by jon1270 at 11:02 AM on November 30, 2019 [6 favorites]

Was going to suggest a torch but then realized, like Frankenstein’s monster, FIRE (probably) BAD.

On preview, yep: Angle grinder with cutting wheel would be my next go-to.
posted by supercres at 11:03 AM on November 30, 2019

(Corded is less convenient but cheaper and more powerful)
posted by supercres at 11:05 AM on November 30, 2019 [2 favorites]

Also consider gathering enough friends to carry it out whole.
posted by jon1270 at 11:08 AM on November 30, 2019

I'd wear a respirator and ear protection as well.
posted by leslies at 11:17 AM on November 30, 2019 [8 favorites]

Again, however, wear full eye protection and given coal, probably lung protection also.

If the grinder is a no-go, you can probably use a serious drill (maybe rent?), an appropriate bit, and a lot of time to drill a series of holes in a line and then crack the iron along that weakened plane with a hammer and demo chisel. Rinse, repeat.
posted by aramaic at 11:17 AM on November 30, 2019

There may be coal dust, keep a fire extinguisher at hand, have a clear understanding of your exit path.
Paying a skilled person and assisting them seems like a fine idea.
posted by theora55 at 11:22 AM on November 30, 2019 [12 favorites]

Don't blame (only) the HVAC contractor. They probably quoted the previous homeowner a price for hauling the old furnace away that the homeowner didn't want to pay but barely covered the contractors' cost. They'd have to chop it up and haul it out in pieces just like you, and that would take one guy (maybe two if there's enough space) most of a day ; in which they wouldn't be doing anything else (like installing the new system).

But yeah, corded angle grinder (Harbor Freight quality is just fine for this job) with cutting wheels, full ear/eye protection + respirator, and a nearby fire extinguisher. It'll probably take you a couple of days. Or find someone who'll do it, but it won't be cheap (which is undoubtedly why the previous homeowners didn't have it done).
posted by jlkr at 11:29 AM on November 30, 2019 [2 favorites]

Did the previous owners' HVAC contractor remove all the asbestos, though?
posted by Iris Gambol at 11:29 AM on November 30, 2019 [8 favorites]

Response by poster: Thanks for the replies. I will look into getting a good corded angle grinder and/or a corded reciprocating saw.

Other things:

1, It looks like it was converted to burn natural gas before it got put out to pasture - I'm pretty sure there's no coal or ash inside. I have earplugs and n95 masks and I will wear both plus goggles before trying anything.

2, I'd love to pay a pro to do this, but funds are limited.

3, There are bolts holding some of the pieces together, but they are all very rusted, and the coal pit itself is all one piece and far too big to be luggable even if I got the other parts off of it.

4, It's too big to go out intact, even if my friends were from Krypton and didn't care about the weight. It must have been lowered into the basement before the main floor and walls went in.

5, Some of the ducts do have asbestos on them, yes. So did the old furnace. I hosed the furnace down, then scrubbed the asbestos off while it was soaking wet (asbestos is harmless if it can't raise dust). That was the easy part.
posted by Glaurung at 11:48 AM on November 30, 2019 [2 favorites]

oscillating tool with a bimetal blade?
posted by 5_13_23_42_69_666 at 12:16 PM on November 30, 2019

Since it's bolted together, a good prybar might be enough to break it into pieces, especially if it's cast iron.
posted by jamjam at 12:17 PM on November 30, 2019 [1 favorite]

You can cut the bolts with the angle grinder. That’ll make separating parts easy.
posted by jon1270 at 12:57 PM on November 30, 2019 [2 favorites]

Oxy-acetylene torch would make quick work of it. I would check around a bit on Craigslist; for the price of a good angle grinder and enough ablative wheels (and you'll need a lot of them—cast iron is harder to cut and eats up wheels faster than steel) to cut the thing up into chunks, you might be able to get someone to come in and chunk it up. To say nothing of the value of your time.

Search CL for "mobile welding" and if that doesn't turn up anything, possibly even search the wanted listings for "scrap metal". Some scrappers will have torches for exactly this sort of thing.

Edit: If it's made of smaller components held together with bolts, that's a different story. I'd use an angle grinder to cut the bolts—which are probably steel—and then beat it apart with a cold chisel and an engineer's hammer. But if the cast iron components are too big to carry out, then it's torch time.
posted by Kadin2048 at 3:17 PM on November 30, 2019 [2 favorites]

10 Amp Deep Cut Variable Speed Band Saw from the harbor place and oil to help with the cut , how I'd do it no sparks no fumes bandsaws are smooth cutters once you get it going .
posted by hortense at 6:36 PM on November 30, 2019

A 5 pound hammer (with a short handle) and can be about as effective as a sledge hammer, less tiring and easier to control.
posted by bonobothegreat at 7:10 PM on November 30, 2019

If you are hoping to break the thing up I'd start with a drill and see if you could do some damage to the thing with that. You can crack things that have holes in them much more easily than things with an unmarked surface, and cast iron will crack. You may want to look into renting some bigger and meaner tools than just a reciprocating saw. There are places that rent tools to contractors - the ones who rent scaffolding and such, that might be able to rent you a tool more heavy duty than what you have. A reciprocating saw probably doesn't have the weight, let alone the motor power to do very much. If you force it down hard enough to do the work either your blade will break or the motor will burn out or both.

However you may have to start to look for other long term solutions or satisfices. Things to consider: If you take the floor out temporarily in some location and if you lift the firebox out through that opening, or would the thing just be stuck on another floor in your house? Just how much more difficult would be taking out the floor compared to dismantling the furnace. I would rather remove a floor and replace it than try to take a cast iron furnace apart. Removing and replacing floors is more in my weight class, than removing and replacing furnaces. But are the doors one level up wide enough to bring it through? Would the floors upstairs even be strong enough to support the furnace?

If you get as much of the bolted on bits off as possible, can you shift the thing at all? If you can, would it be possible to put it in a corner and build something over it to cover it and leave it down there?

How about if you dug a pit beside your house and took out a chunk of the wall? Could you get it out via a hole in the structure that way? Any chance you have been planning on repairing or replacing some of the basement wall?

Would a long term project, like putting in half an hour sawing every weekend and every evening in the summer chip away at this so that in a couple of years you'd have it done, and would that be more practical than trying to get it done in one big push? If it will take 100 hours of sawing/drilling/sledging then it is a year long project.

Please wear protective equipment while doing this work - sledgehammer work, or simply five pound hammer work can result in significant arthritis type damage to your hands from the impact that is transmitted into them - so don't neglect to make sure you protect yourself from any possible hazards.
posted by Jane the Brown at 2:08 AM on December 1, 2019

What is the finish of your basement floor? Might it be possible to remove some basement floor and then bury it below the house? But is your house built on rock?
posted by Jane the Brown at 2:18 AM on December 1, 2019 [2 favorites]

For the potential youtube video alone, I'd suggest thermite.
posted by coberh at 11:56 AM on December 1, 2019

A cutting torch will not work on cast iron AND loose soot is rapidly flammable.
posted by Raybun at 1:16 PM on December 1, 2019

I would second the suggestion of finding a local welder. A plasma cutter will make short work of cast iron, and any mobile welding pro will have one.

If you are going to do it yourself: If you are not familiar with using a cut-off wheel (zip wheel) on an angle grinder, please be aware that they can shatter when damaged. They do not like to be bent or wedged in tight. Straight cuts are your friend. Eye, ear, and breathing protection are a very good idea. Keep yourself as much out of the "line of fire" as possible, should the disc shatter. Resist the impulse to remove the grinder's guard.
posted by xedrik at 5:28 PM on December 1, 2019

Also, since cast iron can shatter into jagged shards, as can blades and disks, I'd wear something that protected my throat. Either a heavy piece of material or a full face protector like is worn for lathe work.
posted by bonobothegreat at 6:39 PM on December 1, 2019

Is it possible that you could make it rust? It wouldn't make it disappear but it might make it weaker and easier to deal with. There are ways of making things rust faster using things like salt and peroxide.
posted by Melsky at 6:44 AM on December 2, 2019

A demolition hammer might do this job. It can wreak a lot of things in a hurry. You can rent one.
posted by Midnight Skulker at 10:24 AM on December 2, 2019

They do make specialized diamond coated blades for the reciprocating saw - not outrageously expensive (10-20$), and specifically made for cast iron. If you've already got the saw, it might be good for you. Unfortunately, I do not have experience cutting cast iron with a reciprocating saw.
posted by Dmenet at 11:26 AM on December 2, 2019

I have a truism that I wholeheartedly believe applies to this situation:
"If you think hiring a professional is expensive, try hiring an amateur!"
This is one of those Big Jobs that someone moderately handy may believe he or she can tackle alone with the right tools, but in fact is fraught with extreme danger for the untrained. By choosing the cheap route (doing it yourself) you are in fact half-assing the job and exposing yourself, your family, and your home to the following dangers, all of which have been mentioned above:
1) FIRE: You're proposing to use power tools that are unfamiliar to you, to disassemble a huge burning apparatus that is unfamiliar to you. What all is in it? What kind of sparks/dust/ash will you be producing? Can you afford the real risk of an accidental fire starting in your basement?
2) ENVIRONMENTAL/CHEMICAL: Was the furnace properly abated at any time? Almost certainly not, which means asbestos or other hazardous materials may be within, waiting for you to set them loose all over your basement and house. Can you afford the real risk of needing an emergency asbestos cleanup, or the medical consequences of inhaling whatever else might be released?
3) PHYSICAL TRAUMA: You've received some sage advice here about the danger of using high-power tools on cast iron and steel. Have you ever been trained on proper protection and practices for such a job? Can you afford the financial fallout of a significant injury resulting from metal shrapnel, including lost work and medical bills?
Do you really want to essentially improvise for a job that could easily result in serious injury, death, or major damage to your home?
Sweet Zombie Jesus, hire a pro for this job. Take out a loan if you have to, or leave it alone.
posted by BigLankyBastard at 12:53 PM on December 2, 2019 [1 favorite]

An angle grinder is how I'd do it, but absolutely agreed that you should not tackle this yourself.
posted by aspersioncast at 3:52 PM on December 2, 2019

Please dont do this yourself. Call your local ironworkers union and see if they can help.
posted by WeekendJen at 1:35 PM on December 9, 2019

Some concrete contractors have saws that also cut iron pipe (diamond chainsaw) ,look for concrete cutting in your local listings .
posted by hortense at 7:17 PM on December 9, 2019