Fireplace draft, everyone likes a puzzle
I know this isn’t the typical question here, but I do know that someone in this form can help. An older house that I just moved into has a wood fireplace in the finished basement. The fireplace has two glass doors that are surrounded by a 3″ band of metal grate (this pulls in and pushes air). There are two 6″ holes (with ducting) above the firplace that exhaust warm air from the fireplace to the ceiling of the house (there is no powered blower).
There has been a crazy cold draft coming from the metal grate when the fireplace is not burning. The flu seals well (inside the glass doors and pit). I went outside and found a “dryer like” exhaust with a 3″ hole covered by a piece of mesh screen. I think this is somehow connected to outer box of the fireplace (where the metal grate is).
While outside the house, I decided to fill the dryer like intake with insulation (just packed it in) and the draft has been minimal.
Can I run my fireplace without unplugging this intake hole?
Replies
no.
That's a fresh air intake. My fireplace has a valve inside, to open/close this- the structure around your firebox has to have some sort of inlet to allow this air in.
If you don't have an intake, the fire will draw combustion air from your house, and burn the warm air. It can create negative pressure in your living space, and cause flue gases from your furnace or hot water heater (if they're gas...) to come back down into your living areas.
Also, when you close the doors, the fire could starve for air.
The older I get, the better I was....
Thank you. I don't see a valve or lach anywhere, so guess I have to unplug it manually.
Yellow,
None of my business but...
"... a crazy cold draft coming from the metal grate when the fireplace is not burning." For there to be a slight draft coming in, you have to have negative air pressure in your house, already. That means that what the other person posted could happen, is already happening.
There should never be a time when there is negative air pressure in a house with gas heaters/gas stoves/gas water heaters. You should always have a fresh air supply for these appliances close at hand.
I know, you've heard it before... It bears repeating. Flue gases can be collecting in the house and the killer, CO (carbon-monoxide), is an odorless gas heavier than oxygen and nitrogen. It displaces oxygen. Not bad if your intention is to kill mice; but, bad if you intend to be around to be happy about the mice dying. Every time you open the door, you let some out, at the bottom of the door, as the inside and outside pressures equalize.
A friend of mine died with his dog, two daughters, wife, and 6 new-borne chocolate Lab puppies from CO poisoning. Cause? Dead pigeon in the hotwater heating flue that no one knew was there. There was a RAG stuffed in the fresh air pipe to the fireplace to keep the cold air out. Snow covered the gap under the front and back door overnight No CO/CO2 alarm.
Had any unexplained headaches lately? Fix this NOW before you sleep in that house again, friend.
William
Thanks for the post. Very scary, I will proceed with urgency.
Where do I start? Revove the insulation to let the cold draft in through the Fireplace?
I do not know where to begin to address the negative air pressure?
I do not have a CO2 Detector, but will pick one up today. Where should I locate it, basement where the fireplace is or upstaires/mainfloor?
Our Side/main door is located on the side off our house (we do not use the front door). This side door has a fork: staight into the Kitchen or take a right down the staires. Consequently, when you open this side door, cold air rushes right down the stairs into the basement where the firplace is.
On another side note: to start the fireplace I open the side door upstairs to flood the basement with cold air. this seems to let the warm air of the starter fire up through the flue. If I do not open the side door, smoke fills the room because with the flue open and the draft, the fire is hot enough yet to push the warm air and smoke up the chimney.
I would suggest you put CO2 detectors by the bedroom area(s) and by any area(s) where there is combustion. They are cheap and not worth having a tragedy happen like the pervious post indicated. FYI in my 2900 square foot house I have 5 CO2 detectors.
Good luck,
Jay
Don't Panic!
Carbon monoxide is truly dangerous stuff, but what you are describing does not mean that you have carbon monoxide accumulating at lethal levels in your home, despite what the other postings are suggesting.
What you are experiencing, a draft coming into a house in a cold climate, is ordinary chimney effect. Warm air rises and leaks out through upper areas of the house and it is replaced by air leaking in wherever it can. Probably every house in the northern U.S. and all of Canada shows this effect six months or more every year.
The common chimney effect is not the same thing as significant negative pressure being created by fans or blowers pulling air out of an especially tight structure and causing replacement air to be drawn in through gas appliances because there is no other source for replacement air. This usually only occurs in exceptionally air tight houses, usually a home built to be super energy efficient, without proper engineering.
Second point is that in addition to true negative pressure you also need a source of carbon monoxide, typically in a home this would be a gas furnace or gas hot water heater. Oil furnaces are rarely the source of carbon monoxide poisoning because there are blowers on the oil burner that will overcome the effect of at least moderate negative pressure.
I should also point out that the tragic incident described was not caused by negative pressure, the chimney was blocked and the combustion gasses, not having an exit, accumulated in the house. This is a very common scenario for residential carbon monoxide poisoning and it is usually caused by poorly installed or poorly maintained gas appliances and their chimneys. I personally know of several similar incidents.
Having said all this, all homes should have at least a few carbon monoxide detectors, this is doubly important if the home has conventionally vented gas appliances and/or an attached garage.
Personally I don't think any home should have conventional gas furnaces or hot water heaters, though direct vent appliances are fine, and no home should have an attached garage.
John W.
and no home should have an attached garage.Geeeee There goes my Shop!
A shop is a good use for a garage, it's the car in the garage that's a problem.
John W.
This thread would perhaps get more expert attention in Breaktime. If you live in a cold climate (of course you do, or you wouldn't have a wood stove), there will be a natural tendency for your house to act like a chimney, drawing from low points and losing air through high points, so unless the house is incredibly tight it's not unlikely that cold air would be drawn in. Your points about having a CO detector and checking for excessive negative pressure are good ones.Pete
Closed glass doors are kind of nice.. If sealed well..
I'd leave the vent open for when you use the fireplace.. Just me that is.
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