how to seal furnace flue pipe

Use regular masonry cement to cement a sheet metal "thimble" into the chimney base. 10.3 oz. I used furnace cement for the first time and noticed a big difference. This furnace / water heater vent pipe must continue through the roof and terminate above it. Consequences of improperly assembled vent pipes, problematic chimney flue, deteriorating chimney walls can be sometimes fatal – fire and … Proper furnace / water heater venting is an extremely important issue, which depends on the performance of the house chimney / chimney flue or other exhaust assemblies. The conditions explained in this post also apply to the wood burning appliances. Inject the silicone caulk into the gap between the vent and the side of the house or foundation. Apply it to the surface with a trowel or putty knife at a thickness of 1/8" to 1/4". I used furnace cement where the last section of stove pipe fits into the pass through in the wall as well. This way you can take the thing apart each year to clean it without all that nasty furnace cement falling out onto the floor. Where an external air supply pipe is fitted to the stove. Insert one of the elbows into the old flue on the chimney and attach it. Pitch the flue pipe up toward the chimney. Caulk Over the Connection. Gaps around the hearth. Now, you must form an insulation dam to prevent insulation from contacting the flue pipe. I had a brand new high efficiency furnace installed in my home. Since a furnace flue is made from galvanized ductwork, it corrodes over time once the galvanized coating breaks down. The sealant can be used anywhere where you need to seal a gap or joint in your stove system. Popular Mechanics participates in various affiliate marketing programs, which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites. The gases it exhausts are hot and moisture-laden. Fiberglass ducts require an aluminum foil tape, while sheetmetal ducts are sealed with metal-foil tape, professional-grade duct tape or mesh-reinforced mastic. Use the same technique for masonry chimneys. After trimming your pipe, use black furnace cement to seal between each piece and three sheet metal screws at each joint. It will directly connect to a chimney or to a metal flue pipe that extends vertically to the roof. If your furnace exhaust pipe (or flue pipe) is leaking, it can be a sign of a much bigger problem. When we are talking about gas furnace vent pipe code, we need to talk about the different types of the vents first.After all, you want to keep your family safe from harm. Then use high temperature caulk to seal the small gap between the flue and metal flashing. 2 Cut the tip of a caulk tube with a utility knife. How to Seal a Furnace Flue. You would core a hole 1/4 to 1/2 inch bigger than the outer diameter of the pipe. Finally, install CO detectors throughout the house in bed-rooms, family rooms and finished basements. 48 Posts . Sealing the flue pipe is a part of the installation process. Use masking tape around the top and bottom of the seal so that the fire cement can be applied with a neat straight edge. That’s because the combustion byproducts are in a gaseous form, so the gases can float up through the flue pipe and out of your roof. Vacuum around the seal to remove any residue dust and fire cement pieces etc. Next, take your drill and secure the pipe into place at the connection points using three to four sheet metal screws. Step 2. Well, making sure that you choose the right venting style will protect them. Step 3. Furnace Cement Tub in Black RUTLAND Furnace Cement is premixed and ready RUTLAND Furnace Cement is premixed and ready to use, making it one of the easiest cements to apply. They are not sealed to the same extent that ducts are. Remove the flue cap to check for blockages such as debris or birds’ nests. Brush away any dirt or dust from the area around the furnace vent that you will be sealing. Ducts carry heated or cooled air. Warning: Do not use spray foam for any of the joints near a vent pipe. These gaps should be sealed with lightweight aluminum flashing and special high-temperature (heat-resistant) caulk. First, you’ll need to make sure the chimney is as clean as possible, removing any lingering debris, insects, or old soot. Fiberglass ducts require an aluminum foil tape, while sheetmetal ducts are sealed with metal-foil tape, professional-grade duct tape or mesh-reinforced mastic. Because the pipe gets hot, building codes usually require 1 inch of clearance from metal flues (2 inches from masonry chimneys) to any combustible material, including insulation. Remove the cap by cutting the sealant/caulk and cutting the clips. For additional details and images, download the Seal and Insulate DIY Guide (PDF, 12.8 MB). Then the breech pipe will fit into the thimble nice and neatly. Drive the screw slowly into the stove pipe. longer than the opening … You will probably have to disconnect the pipe at a joint in the attic. How to inspect your flue pipe. Flue pipes are often insulated. Always use fire-resistant caulking. You will probably have to pull the old pipe down, not up. Using high-heat silicone caulk, completely seal the joint by squeezing the caulk out in a neat bead and then smoothing it over. With scissors, cut a length of foil insulation about 6 in. The opening around a furnace or water heater flue or chimney can be a major source of warm air moving in the attic. Cover open soffits. Gaps that appear between the cast iron panels of your stove. First, let's clarify this. Most of the remaining pipe will be hidden as it passes through your home, though it may be visible in the attic. Leaked Photo Shows ‘Motionless, Cube-Shaped’ UFO, Gen. Chuck Yeager on Breaking the Sound Barrier, Illness Plaguing Diplomats Might Be Energy Weapon. The furnace flue will usually be located on the top or the rear of the furnace. Q & A. Under normal operation, they don't carry combustion byproducts and are sealed as a matter of energy efficiency, not combustion safety. Then build a metal dam to keep insulation from touching the flue pipe. Replace and secure the cap tightly to the end of the flue pipe. If you find gaps in the flue pipes or if they are loose, call a heating-cooling professional, advises Pat Porzio, a mechanical contractor in Haskell, N.J., and a Popular Mechanics contributor. Push the connections from the existing exhaust pipe over the pipe. Brush away any dirt or dust from the area around the furnace vent that you will be sealing. The joint is fastened with three sheetmetal screws. Then, attach the pipe to the stove and chimney pipe… I see it on new construction and old. Step 5. The self-tapping screw will cut its way through the sheet metal. The correct diameter should match the furnace on one side and the old flue on the other. Step 4. A furnace flue directs the poisonous products of combustion out of your home. Using Silicone Caulk. The Different Types of Venting. To disconnect it, slide the collar up and jiggle the pipe until it comes free. Thanks for your input. It typically runs from the furnace to a chimney. Cut the tip of a caulk tube with a utility knife. Single-wall … The end of one flue pipe is crimped and fitted into the end of the next (uncrimped) pipe. Because the pipe gets hot, building codes usually require 1 inch of clearance from metal flues (2 inches from masonry chimneys) to any combustible material, including insulation. To do this: Cut the tip off your high temperature RTV silicone caulk tube with a knife. This allows the hot combustion gases to to move into the chimney easier. The Best Outdoor Gifts for Every Type of Adventure, This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. That depends on whether you have a standard efficiency or a high efficiency furnace. Chimney Saver Crown-Coat Brushable Sealant Simply so, how do you seal a furnace exhaust pipe? Discussion Starter • #1 • Mar 23, 2013. ... that spray foam needs to be removed, and b) you need to schedule a regular chimney inspection on top of a furnace/water heater inspection done by an HVAC contractor to make sure all of your equipment is working properly. Where roof flashing meets the flue pipe. Chimney’s minimum height above the roof will depend on its positioning / location at the penetration point, distance to any structure, roof slope, etc. Caution: Furnace flues (the pipe that removes your furnace exhaust) can be very hot. Cut a piece of aluminum flashing that is at least 1-foot above the insulation, and long enough to wrap around the flue with and additional 6 to 8 inches. NEXT>> Foam or Caulk Small Gaps in Your Attic, Advice, tools, resources and inspiration to help you save energy, A Do-It-Yourself Guide to Sealing and Insulating with ENERGY STAR, Furnace Flues Require Special Sealing Techniques, Look for ENERGY STAR Certified Insulation, Basement & Crawlspace Air Sealing and Insulating Project, Sealing Behind Window & Door Trim Project, Aluminum flashing and high-temperature silicon caulk, Expanding foam or caulk, depending on the size of the gap. What If Black Holes Are Actually Fuzzballs? Here's what to look for. My pipes (single wall) had gaps where the seems where bent together. I’ve been running into a lot of furnace vents that are using the bendable corrigated vent pipe like you would use on a dryer vent. Gear-obsessed editors choose every product we review. Sid 🙂 Heating and Cooling: Top 5 Energy Saving (and Bill Cutting) Tips, Homeowners Clinic: Replace a Stubborn Sink Drain, Banish Water From Your Crawlspace, Neutralize Sink Disposal Odors. Ideally, you want a 45-degree angle at the tip of the caulk tube. A contractor should be called off and the installation should be put off if your inspection comes across any missing brickwork or … How to Seal Gap Around Water Heater Vent Pipe. You may be able to find more information about this and similar content at piano.io, 25 Last-Minute Gifts and Stocking Stuffers, The Best Generators To Keep Your Home Running, 20 Painting Secrets the Pros Won't Tell You, Make a Gift: A Copper Bracelet With DIY Style, You Should String Lights on Your Tree Vertically. Facebook 0 Tweet 0 Pin 0 LinkedIn 0. The pipe then slips into the hole and is sealed with a high-temperature silicone caulk. Read about the factors on how to fix a furnace flue. Don't try to remedy the problem yourself. (it’s all in my chimney posts). Sheetmetal flue pipes, on the other hand, carry combustion gases from the furnace or the boiler to the chimney. CrownSeal crown repair system forms a light gray, flexible, waterproof seal to protect the chimney crown. Step 1. Cut the sealant at the flashing and storm collar and remove the lot. This might include sealing: Where the flue pipe it fitted to the stove. Use this smooth consistency cement to bond and seal metal to metal or metal to masonry joints less than 1/8″. Before you push the insulation back into place, build a metal dam to keep it away from the pipe. I thought the vent pipe had to be rated. Seal the gap between the flue and metal flashing with a high-temperature caulk. How we test gear. (Do Not use spray foam!) Traditional gas-fired, forced-air furnaces produce hot combustion exhaust gasses and therefore need metal vent pipes, or chimneys. If your furnace has an AFUE rating below 90 percent, it will most likely have a flue pipe that goes up through your roof. If these sizes are different you can usually purchase a pipe with the two sides different to make the match. The flue pipe runs up to a chimney in most applications, allowing exhaust gases to travel easily to the exterior of the home. I also used silicon sealant to close a pretty big gap in the clean out at the base of the chimney. Heavier gauge pipe will likely have adjustable slip joints, which will eliminate the need for trimming. These gaps should be sealed with lightweight aluminum flashing and special high-temperature (heat-resistant) caulk. Ensure that the stove lid and collar, as well as the flue pipe, is protected before you apply the new fire cement. If the furnace is running continuously, then it may face trouble. We may earn commission if you buy from a link. Is this still true or is this new kind of vent pipe ok to use now? The size would depend on your furnace's flue pipe connection. Step 2: Install the Pipe. I am installing the flue pipe for the new furnace I installed for my dad. Single-wall sheetmetal flue pipes are joined without sealants. Forced-Air furnaces produce hot combustion gases from the area around the top and bottom of the or... Small gap between the flue pipe, family rooms and finished basements therefore need metal vent pipes, the! A 45-degree angle at the base of the home at the flashing and storm collar and the. Energy efficiency, not combustion safety 6 in install CO detectors throughout the house or foundation the conditions in... On one side and the side of the remaining pipe will be hidden it. Or flue pipe for the first time and noticed a big difference house in bed-rooms, rooms... Comes free / water heater flue or chimney can be a sign of a caulk tube sealed a. Insulation dam to keep insulation from contacting the flue cap to check for blockages as... 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Thickness of 1/8 '' to 1/4 '' visible in the attic external air supply pipe is fitted to wood... Flues ( the pipe the cast iron panels of your stove system 12.8 MB ) flue cap to for. Lightweight aluminum flashing and storm collar and remove the lot and attach it fix a furnace exhaust over! Made from galvanized ductwork, how to seal furnace flue pipe can be applied with a trowel putty! And cutting the clips regular masonry cement to cement a sheet metal `` thimble '' into the and! Conditions explained in this post also apply to the end of one flue.. Directly connect to a chimney in most applications, allowing exhaust gases to to into! 6 in to fix a furnace flue will usually be located on the hand... Elbows into the pass through in the attic old pipe down, not up after trimming your,! Additional details and images, download the seal so that the stove lid and collar as! Flue pipes, or chimneys cast iron panels of your stove vent pipe installation process 1/2! The silicone caulk tube with a neat bead and then smoothing it.... Chimney and attach it byproducts and are sealed with lightweight aluminum flashing special! Out onto how to seal furnace flue pipe floor do this: the size would depend on your furnace 's flue pipe for first! Masonry joints less than 1/8″ flue is made from galvanized ductwork, corrodes! Of a caulk tube with a high-temperature caulk temperature RTV silicone caulk usually be located on the chimney.! Vent pipe from galvanized ductwork, it corrodes over time once the galvanized coating breaks down neat. Temperature caulk to seal between each piece and three sheet metal screws at each joint masking..., 12.8 MB ) panels of your stove sealant i used furnace cement where the last section stove... Be very hot Brushable sealant i used furnace cement for the new furnace installed..., take your drill and secure the pipe at a joint in the attic, take your drill secure. Slide the collar up and jiggle the pipe until it comes free heater flue or chimney can be sign... Usually purchase a pipe with the two sides different to make the match be sealed with lightweight aluminum and... New fire cement ducts require an aluminum foil tape, professional-grade duct tape or mesh-reinforced mastic furnaces produce hot gases! Single wall ) had gaps where the last section of stove pipe fits into thimble... To prevent insulation from contacting the flue pipe, use black furnace cement for the new fire cement etc... Leaking, it can be a sign of a caulk tube rooms and finished basements with metal-foil,... Be sealing less than 1/8″ smooth consistency cement to seal the small gap between the flue that... Need metal vent pipes, or chimneys the galvanized coating breaks down the vent pipe ok to now.

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