Strange Chimney Cap

[Mike Lamb]

This is the hood on a clay lined wood burning fireplace chimney converted to gas logs. What do you make of this?

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[Bill Kibbel]

It's a cap that's typically installed as a last attempt to correct down-draft problems. Google Vacustack or something close to that.

The gas conversion should have triggered a level II.

[kurt]

Flue looks too small, with a last ditch effort to make it draft with the flaky flue hood.

[mjr6550]

It is a wind cap, but I don't see anything close enough to cause downdrafts. Could be that the flue is small. The cap looks small.

[Bill Kibbel]

Flue looks too small, with a last ditch effort to make it draft with the flaky flue hood.

How do you determine a flue is too small without seeing/measuring the fireplace opening to flue ratio?

[kurt]

Magic, Bill. Magic. I'm a natural man....I see it, I feel it.

Mike asked, reasonably and thoughtfully, what folks made of this situation. So I said what I thought. For those unable to read words for what they are without projecting meaning upon them, I said it looks small. No "determination" was made one way or the other.

For those that work a particular locale for a couple decades and have seen a few thousand Chicago 8" tile liner chimneys pressed into service for fireplace use with a complete lack of draft, it's a reasonable guess.

Thousands upon thousands of Chicago houses had/have these nearly fake fireplaces. Lacking adequate fireboxes, smoke shelves, properly sized liners, or any other semblance of an actual fireplace accoutrement properly applied in the quest to bring Prometheus' gift into one's living room......they all choke and back smoke into the house.

The actual reasons for the lack of draft can be explained with a little high school physics, but because I paid little to no attention in high school physics, instead following my muse in tracing the path of the great Gaugin, I can't explain it in high school physics terms without brushing up on my homework.

So I guessed and said it looked small. Because there's tens of thousands of them throughout Chicago.

And they're all too small.

[Mike Lamb]

The gas conversion should have triggered a level II.

For me, nearly all fireplaces trigger a level II.

[kurt]

With (Lake Bluff folks name withheld in the hope they don't sue me) on the job recommending relines for just about everything, it's a good idea to call for it on any fireplace regardless of new, old, converted, or whatever.

[hausdok]

We have a ton of fireplaces converted to gas logs out here and I've never seen anyone use one of those on a flue.

[kurt]

It's not about gas conversion. It's about draft problems. People install them mistakenly thinking they can get their crappy bungalow fireplace to draft.

[Greg Booth]

It's not about gas conversion. It's about draft problems. People install them mistakenly thinking they can get their crappy bungalow fireplace to draft.

..........exactly so. I installed one of those caps about 25 years ago on my chimney serving a wood stove that I used full-time. Think it was called Vacustak or some such name. My problem was down-drafting whenever we had wind out of the northeast (rare) - it did the job and solved the problem..........Greg

[Mike Lamb]

It's not about gas conversion. It's about draft problems. People install them mistakenly thinking they can get their crappy bungalow fireplace to draft.

..........exactly so. I installed one of those caps about 25 years ago on my chimney serving a wood stove that I used full-time. Think it was called Vacustak or some such name. My problem was down-drafting whenever we had wind out of the northeast (rare) - it did the job and solved the problem..........Greg

I have read good reviews on the internet for this contraption in regards to helping with backdraft issues. Prices range from $100 to $800 for copper.

[kurt]

They can work in some situations. I tried one on my own crappy bungalow fireplace >20 years ago.....didn't work. I think they do well for wind driven draft issues, but not if the fundamental components are screwed up.

The only thing that got my fireplace (w/the 8" liner) to draft was when I ditched the firebox, put in an old Jotul stove, and then preheated the chimney with my plumbers blowtorch. It'd take about 15 minutes of blasting to get it warmed up enough to where it would draft, sort of. Everything would be (sort of) OK for several days until I had to kill the fire and clean out the stove. Then, it was the same drill again. Did that for one winter, closed up the hole, now it's bookshelves where the fireplace used to be.