DEAR TIM: I've got both a fireplace and a free-standing wood heater spaced 15 feet apart from one another in my open kitchen and living area. The fireplace has a fresh air vent in the hearth. I've only used the fireplace twice in fifteen years because when I start a fire in the fireplace, it pulls a sooty smell from the wood heater. Surprisingly, I do not get the smell when I use the wood heater. I'd like to install gas logs in the fireplace. Will gas logs pull air from the wood heater and cause the same sooty smell? Jamie L., Gulfport, MS

DEAR JAMIE: I would be willing to bet money on my answer: Yes. Based upon your description, you are experiencing back drafting. When the fireplace is burning, it is consuming vast amounts of air each minute. It can easily be 250 to 350 cubic feet of air per minute. The fresh air vent in the hearth may be blocked or it may not be able to supply enough air to satisfy the appetite of the fire. The additional air to feed the fire must come from somewhere. Simple physics will tell you that the air will enter the room through the path of least resistance. In your case, it appears the air has decided to enter the room through the flue of the wood heater.

Back drafting is an enormous problem. It is a by-product of the constant push to make homes more energy efficient and air tight. The trouble is, homes are equipped with things that blast air, and lots of it, out of the living space. Have you ever stopped to think about what happens when you activate the switch for your bath fans, kitchen cooking ventilation fans and central vacuum cleaner? What happens when you turn on your clothes dryer? These devices exhaust air outdoors and in doing so create a partial vacuum in your home.

If you do not have an air inlet to re-supply the exhausted air, the replacement air will leak in through windows, doors, chimneys, water heater and furnace exhaust piping, cracks in the house exterior, etc. If several appliances are operating and the demand for air is great enough, exhaust gases from fuel burning appliances can be sucked backwards into your home. This can cause dangerous carbon monoxide to be pulled back into your home.

Many modern furnaces and water heaters have built-in pathways for the air needed to burn the fuel. In fact, virtually every residential building code mandates that combustion air for fuel burning appliances be supplied to fuel-burning appliances. But more air than combustion air is needed in the average home. For years, commercial and institutional building codes have required this extra ventilation or make-up air. This air creates a healthier interior environment, insures that plenty of fresh air is entering the building and that dangerous back drafts are avoided. It is in your best interest to provide this ventilation or make-up air.

This thinking is not new by any means. There are companies that actually sell sophisticated air exchange devices that provide some or all of this needed ventilation or make-up air. But I am not so sure that you need to invest in this equipment. If you do decide to investigate these appliances, be absolutely certain that you see a clear rate of return on your investment. In my opinion, there may be some more practical and far less-expensive solutions.

One device I have seen is very ingenious. It looks similar to a dryer exhaust hood, only larger. Instead of having one pipe feed into this hood, there are two four-inch diameter pipes that connect side-by-side to this fresh air vent. One of the pipes connects directly to the cold air return duct of your forced air heating and cooling system. When your furnace or air conditioner operates, fresh air is pulled into your home. The other four-inch pipe serves as a primary or auxiliary combustion air supply. This pipe terminates near your fuel burning appliances. In your particular case, you could possibly terminate this pipe very close to your fireplace to provide the necessary added combustion air.

Click here to watch the video on these air vents.

You may wonder if the introduction of cold or hot air into your home will cause your energy bills to rise significantly. In actuality, they may stay the same or drop. The air that is consumed by the fans, clothes dryers, vacuums, fireplaces, fuel burning appliances, etc. is coming in anyway to offset the vacuum produced when these things operate. By installing a simple device to cause this air to enter in just one place instead of many different places, the thermostat that controls your furnace and air conditioner may actually cycle on fewer times each day.

Still Need Help? Type Your Keywords Here: (examples: drywall repair, pilot light goes out, poor lot drainage, crown molding guide, etc.) Your Facebook friends would love to know how this column helped you solve your problem. Type a quick comment of what you discovered here at AsktheBuilder.com. Thanks!

Comments: Welcome! I, Tim Carter, don't answer questions here. If you post a question here in the Comments Area, perhaps another visitor will help you. You need to go to the Ask Tim page if you want a question answered. Once there, look closely at how many weeks behind we are. Please be patient as you use this free service. If you have an emergency and need to talk to me, there is an option there for you. Juan 01 Jan 2008, 16:10 Dear Tim, this dual air intake cap with built in damper is the solution to bring combustion air to my 175,000 BTU tankless water heater. I have looked for units like this, but came up empty. Can you send me a link of either the manufacturer, or a distributor that carries the product? Thanks Juan AsktheBuilder 01 Jan 2008, 17:09 Juan, The brand I used was Equalizair. sandra morley 25 Jan 2008, 09:17 DEAR TIM WE HAD FITTED WARDROBES PUT IN OUR BEDROOM LAST OCTOBER AND WORKING TO PLAN THE FITTER BUILT THE WARDROBES AROUND AND COVERED THE AIR VENT IN OUR BEDROOM, CONSEQUENTLY ALL MY CLOTHES ARE GOING DAMP AND CONDENSATION IS APPEARING ON THE WARDROBE DOORS AND EVERYTHING IN THE WARDROBES ARE FREEZING COLD. WE PAYED A LOT OF MONEY FOR THESE AND WAS FITTED BY A REPUTABLE COMPANY PLEASE COULD YOU GIVE ME ADVISE ON WHAT TO DO ABOUT THIS PROBLEM THANKYOU SANDRA MORLEY. AsktheBuilder 25 Jan 2008, 09:19 Sandra, Uncover the vents..... so warm air can once again enter the room. sandra morley 25 Jan 2008, 09:38 DEAR TIM THANKS FOR YOUR REPLY. THE AIR VENT IS ON AN OUTSIDE WALL ENABLING FRESH AIR TO ENTER THE ROOM THE WARDROBE FITTER HAS GLUED AND SCREWED THE WARDROBE FITTINGS AND BLOCKED THE AIR VENT FROM LETTING THE AIR CIRCULATE AROUND THE ROOM, ONLY COLD AIR CAN BE FELT INSIDE THE WARDROBES DO YOU THINK WE SHOULD CONTACT THE FITTERS TO RECTIFY THIS PROBLEM? THANKYOU SANDRA MORLEY. AsktheBuilder 25 Jan 2008, 09:48 Sandra, Yes K. Howard 14 Feb 2008, 20:51 Hi Tim. We just had our central air conditioner & furnace replaced. The in staller said that we needed a fresh air intake for our furnace. The problem is that he installed an outside vent with a 6' long air duct running into our basement. Now with the cold weather, our basement is ice cold from the air coming in. Should this duct be connected directly to the cold air return of the furnace or is this a normal pratice to just let the air duct hang in the basement? AsktheBuilder 15 Feb 2008, 16:43 K, It is normal to let it hang. You can reduce the size to 4 inches. K. Howard 15 Feb 2008, 17:39 Back to the previous question, the basement is cold as outside now because of the air intake. What can we do about all the cold air coming in & isnt that increasing the number of times the furnace kicks in due to the cold air being introduced into our home? AsktheBuilder 15 Feb 2008, 18:28 K, I can't help you. If you want that room warm, cap the pipe.      View all comments *Name: Email: Notify me about new comments on this page Hide my email *Text: Security Image: Security Image Text:   Remember, Tim Carter doesn't answer questions here in the comments. You need to go to the Ask Tim page.