Is a 3-foot tall sheet steel chimney cap 'functional' or 'aesthetic' ?

The three-foot tall, four-feet long sheet steel fabricated around my chimney is falling apart so I took it down.

All that is sticking up out of the chimney itself are the elaborate spark arrestors (multiple chimneys use the same concrete column) which look like 18" tall space ships sticking out of the top of the chimney.

I realize the cap I removed served an aesthetic purpose; but is that the ONLY purpose?

That is, with the spark arresters (or whatever they are) sticking out of the chimney still intact, what 'function' does the three-foot wide by four feet by two feet painted steel chimney 'surround' cap perform?

A secondary question would be advice for fabricating a new one if it's needed (it certainly would look better with it back on).

Reply to
Aaron FIsher
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Take your specs to a good sheet metal shop and have them build you one. There are nice coated sheet metal types available today that are perfect for painting. If you get one made with these modified galvanized materials it should last for many years.

Joe

Reply to
Joe

Post a photo, its there for keeping smoke away by being high. your setup seems humerous, or dumb.

Reply to
ransley

It may be functional and required by code. The chimney must extend some distance higher than anything with in some distance of the chimney.

I forget the exact figures, but it is easy enough to Google.

Any metal fabrication shop can make one for you Consider stainless steel so it last a long time.

Reply to
Ed Pawlowski

The old one was (apparently) galvanized sheet metal because I don't see any rust but it was very heavy lifting off the chimney (which sticks up off the roof by at least four feet).

The problem is high wind. We get 100mph winds here on the mountain facing the ocean. Over time, the winds caved in the structure.

I'll take a measurement and post that later. I think it needs better cross bracing against the wind.

But, what I'm trying to find out is whether it's actually necessary. It's going to rain tomorrow but when it's dry, I'll try to go up and snap a picture or three to post so you can see what I'm talking about.

Thanks.

Reply to
Aaron FIsher

I'm not sure what's humorous about the setup but when the rain abates, I'll post a photo so you can see what it looks like (or maybe I'll use a zoom lens from the ground to snap a picture for you).

The chimney, which is thirty feet above the ground and about five feet above the roofline should keep the smoke nice and high, shouldn't it?

Besides, the top of the enclosure is just a tad higher than the top of the spark arresters so I don't see how this enclosure does ANYTHING about smoke.

I'm confused. Can someone explain how the enclosure handles smoke?

Reply to
Aaron FIsher

That's what I'm trying to figure out! :)

The chimney is a good five feet above the roofline and the sheet metal enclosure is another 2 1/2 to 3 feet above that (which is just about as high as the spark arresters).

Plus it's a clay tile roof so there's not much nearby to catch on fire.

The one I have seems to be galvanized (no rust) but the wind, which gets to 100mph across the ocean, is what knocked it over. So, whatever I use must be able to withstand moderately high winds all winter.

Reply to
Aaron FIsher

Of course that will make it a little heavier. REading all your posts, I'm amazed you got it down.

You don't say what you burn that needs a chimney, or what the chimneys are made of.

AFAIK the purpose of a chimney cap is to keep critters and rain out. Even the low sulfer oil that I burn in my furnace has some sulfer and soot inside the chimney can turn to sulfuric acid when it mixes with water. I think it still takes a long time to eat through a stainless steel chimney. Are their other combinations that might cause problems, I don't know. Maybe if it rains hard enough it can put out the fire...pretty much kidding. I doubt that.

As to critters, that includes squirrels, birds, raccoons?, and pterodactyls.

Reply to
mm

That should be OK. Three feet above the roof where it comes out Two feet above anything within 10 feet.

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Reply to
Ed Pawlowski

I hate that word SHOULD. The OP's statement sounds like the chimney is high enough. But it could also be higher than necessary, inviting problems. Check with local codes. Usenet is a good thing, but it's like asking the weather tomorrow. I can say what it's going to be HERE, but everyone doesn't live HERE. So, start at the local level, find out the facts, and then build to comply.

When dealing with height, any increase increases the leverage put on it by wind.

Steve

Heart surgery pending?

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Reply to
Steve B

I sounds like the chimney surround is higher than the individual chiumney stacks from the individual units. A photo of that's on the roof now, and a photo of what was removed would sure help!!!!

Reply to
hrhofmann

I'd be more concerned about the flammability of the critters' nests than the critters themselves.

Reply to
ShadowTek

Well, actually, if the chimney is not used long enough for them to build that big a nest, what happens is that when you start the first fire of the season, it gets scary from there. If the nest is small enough, it is all incinerated. That would be in the fall after the young birds had fledged, so there would be no KFC extra crispy. If the nest is big enough to block the airflow, it's an "OH SHIT" moment. If the bird is a mud nester, it may not burn off at all, causing a partial or full blockage that cannot burn away.

All chimneys need a weather cap and varmint barrier.

YMMV

Steve

Heart surgery pending?

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Reply to
Steve B

"Steve B" wrote

After having a bird, then a squirrel, I agree wholeheartedly. Best it SS so it does not rust and discolor the side of the house.

Reply to
Ed Pawlowski

Here (finally) is a picture of the ruined metal enclosure.

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I was wrong on the specs - it's about 2 1/2 feet tall, about 5 feet long, and about 2 feet wide (that's a yardstick on the ground in the pic, for scale).

The enclosure appears to be of galvanized steel, riveted together.

What I would need, to withstand the frequent 100mph winds, is to reinforce or brace it a bit better.

But that still leaves open the question whether this chimney enclosure is merely aesthetic or functional.

Reply to
Aaron FIsher

The chimney appears to be concrete (at least on the outside).

The only things, I think, that are burned up in this chimney that go out the three spaceship-like "things" on top of the chimney (spark arrestors?) are (1) the propane-fired water heater, (2) propane-fired fireplace, and (3) wood-fired fireplace.

Here, for example, is a picture I just took of the three 'things' sticking out.

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What are these three 'things'?

Reply to
Aaron FIsher

i'd vote for cosmetic

Reply to
chaniarts

Here is a photo I just took of the other chimney (with an intact metal enclosure). This enclosure is open to the sky. Is it aesthetic or functional?

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Here is a photo of the three items inside the metal enclosure. Are they spark arrestors? If I have to guess, the three "spark arrestors?" seem to be for the wood-burning fireplace, the propane-burning fireplace, and the hot-water heater. One got tilted over when I took the enclosure down (it was very heavy and high above me on the top of the chimney so I wasn't graceful.)
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And, here is a picture of the metal enclosure back down on the ground. It seems to be riveted together and is about 2 1/2 feet high, 5 feet long, and about 2 feet wide (see the yardstick on the ground for reference).
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My questions:

  1. How to fabricate a STRONGER enclosure (that can be assembled on the roof) on top of a chimney by 1 person?
  2. What is the purpose of this thing? (Aesthetic or functional?)
Reply to
Aaron FIsher

I don't think the enclosure is intended to make the chimney extend any farther than it already does because (a) the chimney is already over five feet above the roofline, and (b) the metal enclosure isn't any higher than the three 'spark arrestors?' on the top of the chimney anyway.

The roof is tile and the chimney is, what appears to be, concrete of some sort.

Here is a pic of the chimney that is intact:

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And, the one where I had to take down the enclosure:
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And, a side view of the destroyed enclosure (don't ask how I got it down all by myself):
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What advice can you give me for replacing it?

What I'm thinking is to either leave it off (if it's not functional) or to assemble a new one on the roof.

Reply to
Aaron FIsher

actually, it might be functional. if you have a strong wind go over the top of that, it may create a stronger draw via the bernoulli effect than if it wasn't there. the vents on the bottom were the clue.

if the sides were bowed instead of flat, they'd shed wind load better.

Reply to
chaniarts

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