Insulating Furnace Flue Pipe: Step by Step Guide
- Step-1: Take Measurements Turn off your furnace first and wait till it cools down enough to touch. ...
- Step-2: Cut Metal Flashing Take two flat sheets of aluminum flashing now and cut them in 14” length. ...
- Step-3: Cut The Metal Notch ...
- Step-4: Apply High-Temperature Caulk ...
- Step-5: Secure The Junction ...
- Step-6: Cutting Slits On The Flashing ...
- Step-7: Placing The Insulation Properly ...
How do you insulate a chimney with a furnace?
These gaps should be sealed with lightweight aluminum flashing and special high-temperature (heat-resistant) caulk. Before you push the insulation back into place, build a metal dam to keep it away from the pipe. Use the same technique for masonry chimneys. Caution: Furnace flues (the pipe that removes your furnace exhaust) can be very hot.
How to insulate a metal water heater flue pipe?
How to Insulate a Metal Flue Pipe 1 Turn the water heater or furnace off and allow the flue to cool to the touch. 2 Measure the circumference of the flue. 3 Cut two flat sheets of aluminum flashing that are 14 inches long and narrow enough to fit between the ceiling joists around the flue. More items...
How much insulation do you put around a furnace vent pipe?
The recommended depth for attic insulation is usually 10-14 inches ( source ). If you have used a 14-inch flashing around the vent pipe, it should be easy to insulate to this level while still maintaining a 4-inch gap at the top. Newer, high-efficiency furnaces do not always have vent pipes that exit through the attic space.
Can you use spray foam insulation on a gas flue pipe?
Warning: Do not use spray foam for any of the joints near a vent pipe. Always use fire-resistant caulking. Now, you must form an insulation dam to prevent insulation from contacting the flue pipe.
Why Should I Insulate Around My Furnace Exhaust?
How to prevent air leaks in attic?
Why do you need to seal air leaks in the attic?
Why do you need to form an insulation dam?
How many ways can a furnace vent be constructed?
What type of fan is used to vent out the furnace?
What is triple walled furnace?
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Can you insulate around furnace exhaust 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. These gaps should be sealed with lightweight aluminum flashing and special high-temperature (heat-resistant) caulk.
Can I put insulation around a flue pipe?
Historically, people have used the term "flue" and meant the chimney itself. So, with all of this information, the answer is you shouldn't insulate around a chimney. There are better ways to keep cold air out and losing the air you pay to condition.
Should you insulate furnace flue?
While it's not necessary that the furnace vents are insulated, it is essential that they are sealed properly. You may be surprised to learn that the vents can cause you to lose anywhere from 20 to 35% of cool or heated air if they are leaky.
How do I keep my furnace exhaust pipe from freezing?
During the winter months, ensure that the exhaust vents are clear, with no snow or debris blocking them, as this can cause water to enter the system and freeze there. Ensure that the area around and below your furnace vent is cleaned to prevent anything from entering the system.
How do you insulate a flue?
There are several different methods for insulating your liner. You can cover a flexible liner before inserting it by blanket-wrapping it with suitable material. Or by pouring Vermiculite, Perlite or Leca granules into the air gap between the liner and flue after/during installation.
Can you put insulation around a furnace?
Related Articles. Insulating the walls and ceiling in a furnace room can reduce heating costs and make the furnace more energy-efficient. Rigid foam insulation is attached to the walls with adhesive, and to the ceiling with adhesive and roofing nails.
How do you seal a furnace flue?
How to Seal My Furnace Vent PipeClean the area. Remove any dirt or debris from the area around the vent. ... Apply sealant. You can choose either caulking or a foam sealant to seal your vent pipe. ... Clean it up. If using caulking, you may wish to smooth it out after it has been applied.
How do you stop flue condensation?
How to Mediate Flue CondensationAdjust the furnace temperature: Make sure that the furnace temperature is hot enough for the gases to freely flow through the flue and out into the atmosphere.Improve the flue design: Have a professional HVAC tech look at your flue and recommend improvements to the flue's design.
Can you insulate around boiler flue?
One cheap and easy way to finish around the flue is to not touch the flue itself, but to leave a space of 30cm or more from the flue to the insulation. This creates a recess, as shown in the photo, which is a big enough gap to ensure the flue can operate safely, whilst still insulating the vast majority of the wall.
Should furnace exhaust pipe be covered?
If the vent pipes are not protected by screens, you take a big risk for furnace problems due to pipe obstruction or infestations from pests. A simple screen can prevent pest problems, but the wrong type of screen can create other problems.
Can your furnace exhaust freeze?
As exhaust gases condense in the secondary heat exchanger, the moisture then exits the furnace through a condensate pipe that leads to a floor drain nearby or to the home's exterior. If moisture does not properly drain out of the condensate line, it can freeze within the line when temperatures drop below 32°F.
Can snow block a furnace vent pipe?
A furnace vent can also become blocked by a buildup of snow or ice. So whether it's for optimal efficiency or protection from carbon monoxide, it's important to keep your furnace vents clear. Check on your furnace vent during and after heavy snowfalls, and clear snow away from the vent's opening if it builds up.
Can insulation touch chimney pipe?
Fiberglass insulation can't and should not touch your stove's vent pipe. While fiberglass is not flammable, it can melt, causing fire risks. To get around this issue, you need to install a barrier of aluminum flashing between the vent and the insulation.
Can you wrap insulation around stove pipe?
You should never have insulation in contact with a wood stove flue pipe. Most code jurisdictions require the stove pipe be routed through a thimble to provide a safe distance from combustible materials. Air traveling over the surface of the flue pipe may be required to keep it safe and cool.
Can you insulate around boiler flue?
One cheap and easy way to finish around the flue is to not touch the flue itself, but to leave a space of 30cm or more from the flue to the insulation. This creates a recess, as shown in the photo, which is a big enough gap to ensure the flue can operate safely, whilst still insulating the vast majority of the wall.
How do you insulate a vent pipe?
How To Insulate A Vent Pipe In The Attic?Use sheet metal scissors to cut aluminum flashing to size.Apply high-heat silicone caulk to the attic flooring. ... Secure the current setup with a staple gun.Seal the gap in the middle of the flue and flashing.Cut more flashing and wrap it around the vent pipe.More items...•
Why do you need to insulate flue pipe?
Insulating flue pipe is mainly done to contain the heat inside the pipe. But that’s not the only reason to use it. This will give you the additional work of detecting ceiling leaks .
Where to apply caulk to a flue?
Apply some high-temperature caulk around the junction where flue lodges into the attic.
What is double wall furnace flue?
It’s also known as type B vent. Similar to type B, double-walled flue pipes consist of 2 layers of galvanized metal. It also requires a 1-inch clearance between pipe and insulation.
What is the purpose of a flue pipe?
The flue pipe carries carbon monoxide gas from the furnace to the home exterior. It carries the exhaust from burning propane or natural gas.
How many types of furnace flue pipes are there?
Furnace flue pipes are constructed in three types. Let’s go through a brief introduction about them.
Why do we insulate return ducts?
Return ducts are to be insulated only if they affect the air temperature. If it passes hot air into the environment, it’s best to insulate it.
How to bend aluminum flashing?
Bend the notches along with the aluminum flashing at a 90-degree angle. Do these for both top and bottom edges. Wrap the metal flashing circle around the flue pipe.
How much clearance do you need for a furnace?
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. These gaps should be sealed with lightweight aluminum ...
Can furnace flues get hot?
Caution: Furnace flues (the pipe that removes your furnace exhaust) can be very hot.
How to make a flue with aluminum flashing?
Cut two flat sheets of aluminum flashing that are 14 inches long and narrow enough to fit between the ceiling joists around the flue. Cut a semicircular notch into one end of each sheet that is wide enough to fit around the flue and long enough so that the edges around the notches overlap each other by 3 inches.
How to measure flue size?
Cut a piece of flashing to measure the circumference of the flue, plus 6 inches. Cut 1-inch deep slits into the top edge of the flashing, placing one slit every 2 inches along the flashing. Repeat this along the bottom edge of the flashing, but cut the slits 2 inches deep on the bottom edge.
Why does my furnace get hot?
The flue is the metal tubing that extends up from the top of your gas furnace or water heater that carries the carbon monoxide gas from the heating unit to your home's exterior. Because the flue is carrying exhaust from natural gas or propane being burned, it can get hot. This can be a problem when the flue runs into your attic on its way to the roof, as it can heat your attic. Insulating the flue pipe can contain the heat, keeping your attic cooler.
Can a flue pipe be in the attic?
This can be a problem when the flue runs into your attic on its way to the roof, as it can heat your attic. Insulating the flue pipe can contain the heat, keeping your attic cooler.
Why do you wrap a double wall flue with ceramic insulation?
So if I understand correctly, you want to wrap a double wall flue with ceramic insulation to reduce heat loss to your attic to keep it cooler in winter. The ceramic insulation in your application would see lower temperatures then in a triple wall application, and should be effective at reducing heat loss.
Can you put fiberglass insulation around a flue?
Yes insulation like fiberglass and blown cellulose must be kept away like 3 inches from any heat generating source like a flue. Build the flashing around the flue so it comes out at least that far. Then you can add your fiberglass batts next to that.
Can you wrap flue pipe with ceramic blanket?
Of course you can use a ceramic blanket to wrap the flue pipe. Or you can buy triple wall flue pipe that has the ceramic blanket built in. On a triple wall the ceramic blanket is between the inner wall and the middle wall, with an dead airspace between the middle wall and the outer wall.
Is a flue pipe double wall?
The flue pipe looks to be a double-wall pipe as it has some type of special locking tabs at the ends. It also looks very different from the obvious single-wall pipe that runs from the boiler to the point where the flue pipe enters the ceiling at the first floor.
Can you put non-combustibles in the attic?
You can ONLY put non combustibles next to a hot flue. Otherwise you risk creating a fire. Instead of trying to wrap the flue look at where it comes up thru the attic floor. Chances are there is a large gap there that is allowing alot of your warm air from below to enter the attic.
Does insulation help prevent ice damming?
Insulating the flue pipe will help prevent ice damming. A warm attic will help remove snow from the roof, but it will also cause a partial melt of snow and refreezing to ice if the weather is cold enough. baymee. 13 years ago.
What type of insulation do you use for a vert wall?
On the vert walls u need to have a vapor barrier we use a foil type barrier or in our industry we sometimes use our r8 insulation or bubble wrap It works well. Along with the insulation that is there. Without the barrier there is no r value and that is why it is cold around the fire place
What is the minimum clearance between a gas vent and a combustible material?
Minimum clearance between the vent and combustible materials is 3 inches for L-Vent and 1 inch for Type B gas vent. L-Vent or B-Vent that extends through any story above that on which the connected appliance is located is to be provided with enclosures having a fire resistance rating equal to or greater than that of the floor or roof assemblies through which they pass.
How much cold air clearance do you need in Chicago?
Correct. Here in Chicago you need to have 1"-2" "cold air clearance" (depends on location); also looking at the picture it is hard to tell if this is a single or b-vent but in any case just like thekctermite said no insulation around the flue pipe only fire stop thimble at the floor perimeter.
Can you use oil in a DFS vent?
If installed at 1” airspace, it is limited to B-Vent (gas) only. If it is installed at 3” airspace, it it may be used with oil (as an LVent) or gas (as a B- Vent).
Does K wool help insulate?
Once you fire stop the drafting will stop k wool will help insulate around the flue. The vert walls still need a vapor barrier.
Can you insulate against a chimney?
You CANNOT insulate up against that flue. No matter what type of insulation. All chimneys require at least 1" clearance, some require 2" or more. A sheet metal pan/collar around the pipe will seal up the draft when properly sealed with the aforementioned caulking. A sheet metal insulation shield....A cylinder of metal around the pipe sitting on top of the metal pan you need....Will keep any added insulation from contacting the flue and will maintain the necessary air space.
Why Should I Insulate Around My Furnace Exhaust?
When looking for leaks in the thermal boundary, or the perimeter of conditioned dwelling space, one of the worst offenders is the boundary between the home and attic space.
How to prevent air leaks in attic?
A good way to prevent air leaks is to insulate your attic space , but how do you insulate around a hot furnace exhaust?
Why do you need to seal air leaks in the attic?
Air leaks allow too much warm air into the attic and must be sealed to mitigate ice damming. Now that you understand the importance of sealing air leaks and insulating your attic space, let’s look at the steps required to do this safely. There are some important do’s and don’ts depending on your furnace vent pipe.
Why do you need to form an insulation dam?
Now, you must form an insulation dam to prevent insulation from contacting the flue pipe. To do this:
How many ways can a furnace vent be constructed?
Furnace vent pipes can be constructed in three ways and require different clearances:
What type of fan is used to vent out the furnace?
It must use a power-driven fan to force the gases out of the furnace and flue. Most use a small fan to exhaust gases outside, eliminating the need for a chimney-style flue vent. Some slightly less efficient furnaces still use metal piping, but the most efficient models use plastic ( source ).
What is triple walled furnace?
Triple-Walled: Triple-walled, obviously enough, consists of 3 pieces of metal and requires zero clearance . If you are unsure what vent pipe your furnace uses, check the manufacturer’s specs. Unless your furnace is older than the 1980s, you are probably dealing with double-walled vent piping.