Pellet Stove Flue

Pellet Stove Venting Requirements (With Pictures)

In Pellet Stoves by James O'Kelly1 Comment

Pellet stoves work much like traditional wood burning stoves in that they burn a source of solid fuel in order to generate heat for a home, but one of the main differences between them can be the way in which each are vented for both fresh and waste air.

Our pellet stove has a different venting arrangement compared to our wood burning stove and so we’ve explained pellet stove venting requirements below using our own pellet stove to discuss:

  • Whether pellet stoves need to be vented.
  • How pellet stoves are vented.
  • Pellet stove venting options.
  • Whether all pellet stoves need a fresh air intake.

Do Pellet Stoves Need To Be Vented?

Waste air from a pellet stove must be vented to the outside of a home using a suitable form of flue, either within a masonry chimney, internally within a home or externally up an outside wall. Pellet stoves do not typically always require a direct vent for fresh air intake.

When it comes to installing a pellet stove within a home there are two things that need to be considered in terms of venting requirements:

  • The fresh air intake and how fresh air will be supplied to the pellet stove, and to the room if required by local codes and regulations.
  • The flue used to exhaust waste air from the home.
Pellet Stove Front
We needed to consider how our pellet stove would receive fresh air and how it would vent waste air before it was installed

As pellet stoves use a real fire to burn pellet fuel in order to produce heat, both the oxygen supply to the stove the waste air from the combustion chamber will need to be considered in how they will be dealt with prior to installation of the stove.

For our own particular model of pellet stove there’s both an intake air vent and a flue socket located on the back of the stove.

Pellet Stove Back
Our particular model of pellet stove has both a fresh air vent and a flue socket on the back ready for connection with associated vent pipes

We’ve discussed the requirements for clean and waste air venting in pellet stoves below using our own stove as an example.

How Are Pellet Stoves Vented?

The air intake for a pellet stove may use the air within the room or take outside air through the use of a direct vent through an external wall, and waste air from a pellet stove must always be vented to the outside using a suitable flue. Both venting arrangements must meet local and manufacturer’s building codes and guidelines.

We’ve explained pellet stove venting options for both:

  • Waste air leaving a stove and home through a flue.
  • Fresh air intake for supplying the stove’s combustion chamber with oxygen.

Pellet Stove Waste Air Venting Requirements

Waste air from a pellet stove must be vented from a home.

As pellet stoves are combustion appliances, a suitable venting solution for waste air must be provided to ensure that all harmful by-products from a fire are safely removed from a home.

Pellet stoves are sealed systems and waste air cannot simply be left to exhaust back into the room, which is extremely dangerous and goes against all building codes and regulations regarding installation of solid fuel appliances in homes.

There are therefore three possible waste of installing a flue in a home to vent waste air from a pellet stove to the outside:

  • Installing a pellet stove within a masonry fireplace and utilizing an existing chimney. The fireplace opening would need to be big enough to cope with the typically tall size of a pellet stove and a flue liner will typically need to be installed within the chimney for the full length between the stove and the top. See our article on pellet stoves and chimneys for more information.
  • Installing a pellet stove on an internal wall of a home and installing a flue directly up through the roof of the house.
  • Installing a pellet stove up against an external wall of a home. A flue will be installed horizontally through the external wall and then vertically up the side of the exterior wall of a home to above the eaves.

The possible venting arrangements for waste air from a pellet stove may differ depending on the situation, the guidelines set by the manufacturer of the stove and local building codes and regulations.

Our own particular model of pellet stove is too big to fit in our open fireplace and so we’ve had it installed up against an outer wall in our living room, and had a flue installed through the wall and up the outside of an external wall of the house.

Pellet Stove & Masonry Fireplace
We couldn’t utilize our existing chimney for venting our pellet stove because the stove wall too tall for the masonry fireplace

On the back of our stove is an 80mm diameter flue socket in which we’ve connected the flue system to.

Pellet Stove Flue
The flue socket on the back of our pellet stove for venting waste air
Pellet Stove Flue Socket

The requirements for a flue for a pellet stove will differ between regions and each model of pellet stove, but as an example of waste air venting arrangement we’ve had to do the following in order to be in line with the manufacturer’s guidelines (when venting out an external wall):

  • Taking the flue to a suitable distance above the roof line. An exhaust flue for a pellet stove cannot simply terminate after it has gone horizontally through an external wall. The fumes must be released at a sufficient height.
  • No other appliance to be connected to the pellet stove flue.
  • A T-section was recommended at the intersection between the horizontal and vertical parts of the flue for the purpose of collecting condensate.
  • Steel flue pipes in line with local building guidance must be used.
  • The flue system to be hermetically sealed with heat resistant materials.
  • A horizontal section of flue of no more than 2m in length.

These are just the guidelines we had to follow for our own particular model of pellet stove and may differ for you depending on your particular model of pellet stove and your local building codes and regulations.

Pellet Stove Air Intake Venting Arrangements

The air intake for a pellet stove may not have the same strict requirements as for the exhaust flue, but there are still a couple of potential venting arrangements for ensuring that pellet stoves receive sufficient fresh air to the combustion chamber.

Many pellet stoves will have a specific fresh air vent.

For example, there’s a 50mm diameter air intake vent located on the back of our pellet stove.

Pellet Stove Air Vent
The fresh air vent located on the back of our stove to supply oxygen to the combustion chamber
Pellet Stove Fresh Air Vent

The instruction manual for our particular model of pellet stove explains that we have the following two options for air intake venting arrangements:

  • Venting fresh air from the room in which the pellet stove is located.
  • Venting fresh air from directly outside.

When venting fresh air from a room for a pellet stove, there typically doesn’t need to be any components added to the air vent for it to work.

For our particular pellet stove, a fume extractor helps to remove waste air from the combustion chamber to be exhausted from the stove, which in turn creates a vacuum and allows fresh air to be sucked into the stove through the air vent located on the back.

However, the manual for our pellet stove states that if no direct vent is to be used to take fresh air from outside then an external air vent must be located in the same room as the stove to ensure that the room has a continuous supply of oxygen.

For the room in which the pellet stove is located there must be an opening for fresh air with a cross section of no less than 80cm2 in order to ensure a sufficient supply of oxygen necessary for combustion.’


An external wall air vent may therefore be required in the same room as your pellet stove for air supply purposes if your stove will be taking fresh air directly from the room. This is to ensure that the stove doesn’t reduce the amount of oxygen within the room to an unacceptable level.

Although the air supply is being taken from outside for our own pellet stove, there’s already an external air vent located within the same room as the stove, which was installed before we bought the house for other purposes.

Fireplace Vent
if your pellet stove will be taking air from the room then an external wall vent may be required in the same room as the stove is located

Check with the manufacturer of a specific pellet stove and consult local building codes and regulations to confirm whether an external air vent will be required for use with a pellet stove that takes air from the room rather than outside.

With pellet stoves you can also typically have the option of venting fresh air from outside a home.

This would require having a direct air vent extending from the vent located on the back of a pellet stove through an external wall of a home. The manual for our own pellet stove states:

Additionally, the stove can be delivered outside air through a 50mm diameter pipe. The pipe for outside air has to be mounted on the nearest outer wall to the pellet stove.’


Further requirements for our own particular model of pellet stove for fresh air venting include:

  • Using a protective grid where the vent meets the outside air, if required.
  • The length of the clean air vent should not exceed 1m.
  • The outer end of the pipe must end with a 90-degree downward bend, or use another form of protection against the wind.

The requirements for outside air supply to your pellet stove may differ and so ensure to follow the guidelines set out by the manufacturer and any specific local codes and regulations for solid fuel burning appliances.

We’ve gone with using a direct air vent to vent our pellet stove rather than taking air from the room (which some manufacturers recommend for their pellet stoves) as it allows a pellet stove to become a completely sealed system where both the fresh and waste air is kept separate from the air inside a home.

We therefore have a fresh air vent extending from the back of our pellet stove out through the external wall of our living room.

Do All Pellet Stoves Need Outside Air?

Not all pellet stoves require an external fresh air intake vent but may be required depending on local building codes and regulations, and many manufacturers recommend venting fresh air externally for pellet stoves. Pellet stove may also take fresh air directly from the room without the need for a direct external air vent, but may require another external air vent of a certain size to be located in the same room as the stove.

Further Reading

Pellet Stoves Explained With Pictures

Things You Need To Know About Pellet Stoves

Does A Pellet Stove Need A Chimney?


  1. A very useful and comprehensive article – thank you. It answered all of my questions.

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