What is wrong with my fireplace?

December 29, 2014 9:34 AM

The damper is OPEN. The chimney is clean. But every time I build a fire, the flat fills with smoke. Please help.

Every fire I've built at my new apartment eventually ends in the flat filling with smoke, alarms going off, all windows must be thrown open and the place smells like a barbecue for days after.

Building maintenance has verified that the damper is wide open and they had a chimney man come in to clean and inspect the flue. I'm burning dry pinon, and don't pile log after log on, so it's not a huge blaze. I begin by cracking a window nearest to the fireplace. The fires always start out drafting well, but at some point (half an hour to an hour), they continue to draft BUT smoke also rolls back into the apartment.

I've had fireplaces in the past and never had any issues. Can you PLEASE help? I was so delighted to finally have a proper wood fire. Many thanks!!!

posted by 2soxy4mypuppet to Home & Garden (20 answers total)

I think your problem is cracking the window near the fireplace because it gives the smoke another way to exit the building. In fact, a chimney expert told me to seal up all the windows (even upstairs in our two-story house) about thirty minutes before lighting the fire. Especially when it's very cold outside, I also make a torch from rolled up newspaper and hold the lit end above the damper to warm the chimney so it starts drawing the smoke, *then* light the fire I've laid.
posted by DrGail at 9:56 AM on December 29, 2014 [6 favorites]

Response by poster: Thanks, DrGail ... I didn't crack the window originally but then read that I should after having problems with the first few fires... maybe I will try closing things up again. (It is colder than blue blazes here today, and I would love to have a fire.)
posted by 2soxy4mypuppet at 10:01 AM on December 29, 2014 [1 favorite]

DrGail has it. My first thought, "Why are you cracking a window?" When I was a kid and we had fires in our fireplace, we'd all go around the house and make sure the windows were closed. If you have a second opening in the house, it breaks the suction in the chimney and creates a two-way draft.
posted by E3 at 10:02 AM on December 29, 2014

In my case, the chimney was simply too tall and narrow and inadequately insulated to draw for the fireplace in question (the air cooled too much getting to the top of the chimney to keep drawing, I guess); the fireplace had primarily been built for its visual appeal rather than functional use and they hadn't really considered whether or not it WORKED.
posted by Eyebrows McGee at 10:05 AM on December 29, 2014 [1 favorite]

How high above the roofline is the top of the chimney? It's generally recommended that the chimney be at least 3 feet above the top of the roof.

Here's a little checklist of reasons a chimney isn't drawing. You've already addressed some of them.
posted by Thorzdad at 10:13 AM on December 29, 2014 [4 favorites]

Not cracking a downstairs window doesn't make sense to me, but in my experience (I have two fireplaces and use them regularly) problems with drafting well can result from not establishing a good draft in the first place (I was taught the rolled-up newspaper thing but don't always do it) or something competing with the fireplace to suck air out of the house. Upstairs windows might be the culprit, also central air and the exhaust fan over the stove. Although all of those have caused problems for me, the most common is trying to light fires in both fireplaces at once; unless I am careful the second fireplace lit invariably fills up that end of the house with smoke until a good draft gets going. Do you have neighbors with fireplaces that could be using them at the same time as you and are generating a competing draft up their flues?
posted by TedW at 10:13 AM on December 29, 2014

Response by poster: I'm on the fourth floor of an eight-floor building, if that matters. Only the corner units have fireplaces and, as far as I can tell, I'm the only person who actually tries to make a fire. I'll try asking neighbors if any of them have had issues.

Again I'll try without the window cracked, but that was in response to the flat filling with smoke when everything was closed tight. Thank you for your suggestions!
posted by 2soxy4mypuppet at 10:14 AM on December 29, 2014

> It is colder than blue blazes here today

That may be your problem. The cold air in your chimney is blocking it from drawing. The burning newspaper above the damper might work. It's certainly far less likely to cause a five-alarm fire than the “flaming petrol-soaked rag dropped down the chimney” trick I've heard of used in Arctic climes.
posted by scruss at 10:26 AM on December 29, 2014

Do you light from the top or the bottom of the pile? I had problems with smoke going the wrong way but I haven't since I began lighting it from the top.
posted by Kattullus at 11:01 AM on December 29, 2014

Response by poster: I've tried it on 60 degree evenings, too, with the same results. Windows cracked, windows closed, cold weather, not so cold weather. I will try lighting from the top later this afternoon.

What confuses me is that for the first half hour OR LONGER, everything goes swimmingly. Then part of the smoke starts rolling back into the apartment.
posted by 2soxy4mypuppet at 11:02 AM on December 29, 2014

Best answer:

I'm on the fourth floor of an eight-floor building, if that matters.

I think that's your problem. 4 floors is a long way for a chimney to draw, especially if it's very cold out.
posted by Chocolate Pickle at 11:03 AM on December 29, 2014 [3 favorites]

I'm my experience (former owner of three different fireplaces in the Nordic countries - where we burnt fire to survive the winter), I think Scruss nailed it.

Cold air sometimes acts as a cork in the chimney. Effectively blocking warm air to rise. Instead the hot air and smoke escape into the rest of the house. With it a pervasive smell of fire everywhere... Nice if you work as a Boy Scout....

My best tips to get a good drafting fire going: get the air going. Either use newspaper to burn some distance up in the chimney (to blast out cold air). Or my favourite: a couple of tea lights burning for half an hour before you start the real fire. Put the light on a prop a bit up in the chimney to get the draft going.

If you can cover the fireplace hole with a cardboard while the light burn, the better (so hot air moves up the chimney - not out into the room).

Or use a hair dryer to direct hot air up through the chimne. Use it as last resort (as I did after returning to my house in the spell of severe minus degrees). If you're not carefully, you'll get ashes all over yourself, your house and the neighbors cat. But it did get the cold block out if the way.. Yay.
posted by Rabarberofficer at 11:07 AM on December 29, 2014 [2 favorites]

Best answer: I'm on the fourth floor of an eight-floor building, if that matters.

Yeah, I think that's your problem too. Your draw gets momentarily interrupted by wind etc and reestablishes itself but in that long of a chimney you would very easily lose it entirely, especially after your fire cools a bit post lighting. You can try covering the fireplace opening with cardboard but even an enclosed stoves gonna have a hard time with a 60'(?) chimney.

I'm impressed you got it going at all, given that info.
posted by fshgrl at 11:09 AM on December 29, 2014

Best answer: Have a look at this product called SmokeGuard. This is recommended in situations where the flue is too small relative to the fireplace opening. In general, the flue should be at least 1/10 the size, in cross section, as the fireplace opening. And with such a long flue as you have, it probably should be bigger. You can test this by getting a few pieces of sheet metal and temporarily reducing the size of the opening. If this works, you can make that solution permanent by installing the SmokeGuard.
posted by beagle at 11:30 AM on December 29, 2014 [1 favorite]

Response by poster: Thank you for all the suggestions! I will look at the SmokeGuard and this is yet another reason to snag the eighth-floor apartment as soon as it becomes available.
posted by 2soxy4mypuppet at 11:37 AM on December 29, 2014 [1 favorite]

Response by poster: Brookstone has $15 off with the code "HOLIDAYSAVE" so I pulled the trigger on the SmokeGuard. Will report back after it arrives.

http://www.brookstone.com/fireplace-smokeguard
posted by 2soxy4mypuppet at 12:01 PM on December 29, 2014 [2 favorites]

Look forward to hearing how it works. Just as a followup for future reference/clarity, by "cross section" I meant the cross-sectional area. So, if the flue is a 12x12 pipe, or one square foot, you would not want your fireplace opening to be more than 10 square feet. But my guess is that the 10x rule should be more like a 6-7x rule when you have a 60-foot flue. See handy chart at bottom of this page.
posted by beagle at 2:24 PM on December 29, 2014

My suggestion would be to get the fire going as you do, but keep it as big as you feasibly can. The reasoning is that you then heat the chimney, and minimise the heat loss of the hot gas as it heats the masonry chimney walls, and as the gas remains hot(ter) it should rise more reliably.
posted by GeeEmm at 2:27 PM on December 29, 2014

My suggestion would be to get the fire going as you do, but keep it as big as you feasibly can. The reasoning is that you then heat the chimney, and minimise the heat loss of the hot gas as it heats the masonry chimney walls, and as the gas remains hot(ter) it should rise more reliably.

That's reasonable advice, but every fire has to die out at some point. I think in this case the smoking problem arises once the blaze dies down from a nice roaring fire to a smaller one.
posted by beagle at 2:31 PM on December 29, 2014

The problem may be a downdraft caused by prevailing winds blowing across your chimney. You need to break that laminar flow. You could try installing a chimney cap with expanded metal sides ( like a grate) that will allow for a normal draft but break up the air flowing across the chimney opening.
posted by Gungho at 9:07 AM on December 30, 2014