Does a Pellet Stove Need a Chimney? The Surprising Answer!

If you’re considering buying a pellet stove for your home, you might wonder: does a pellet stove need a chimney?

The amazing thing about pellet stoves is that they don’t need a chimney. Homeowners can use a pellet stove by installing a horizontal venting system which is much cheaper and more effective than a chimney.

What if you already have a chimney? Let’s find out.

But before that, let’s understand how a pellet stove works.

How Do Pellet Stoves Work?

Pellet stoves burn pellets to generate heat, which is then used to heat your room through heat exchangers. Pellet stoves are eco-friendly and convenient to use.

Here’s a concise, step-wise explanation of the inner workings of a pellet stove:

Step 1: Add the Pellets.

Pellets usually come in 40 lb bags that need to be stored in a completely dry area.

When you plan on starting up your stove, you add pellets into the hopper.

The hopper is a metal container usually storing up to 70 lbs of pellets. Hoppers come in two varieties: top hoppers and bottom hoppers.

Top hoppers are located above the burn pot. Since these hoppers are more fire-resistant, experts recommend them. Bottom hoppers are present below the burn pot, making it easy for homeowners to add pellets.

Step 2: Auger and Thermostat

A pellet stove has an auger: a screw (made from cast iron) used to move the pellets from the hopper into the burn pot.

Modern pellet stoves come with sensors that measure the number of pellets needed to achieve the temperature set on the thermostat.

When the amount of pellets in the burn pot (where the pellets are burnt) is low, a sensor checks it and signals the auger. Upon receiving the signal, the auger delivers the number of pellets needed to reach the set temperature in the burn pot.

To understand the process, suppose you have started your pellet stove and set the thermostat at 60°F. The auger will start moving the pellets at a certain feed rate to reach this temperature, let’s say 1.5 pounds per hour. Once the set temperature i.e., 60°F, is achieved, the auger feed rate will slow down and maintain that temperature.

Note: If you change the thermostat to a higher temperature, the auger will move the pellets faster. But if you set a lower temperature, the feed rate will be slower.

Step 3: Ignition and Combustion

Two things are needed for combustion: fuel and oxygen. Pellets are used as fuel, while fresh room air provides the required oxygen. But how does ignition occur?

Modern pellet stoves use electrical ignition: homeowners need to press the thermostat button, and an electric spark is induced. The spark ignites the pellets and kickstarts the burning process.

Step 4: Heat Transfer

Pellet stoves use a convection blower that pulls fresh room air and passes it over the burn pot. The passing air makes the pellets burn hotter and more evenly.

As the room air passes through the burn pot, it becomes very hot. This hot air is then passed through a heat exchanger i.e., a series of iron bars.

The iron bars become hot because of the hot air. A blower transfers clean, hot air into the room through these heated bars.

Step 5: Eliminating By-Products of Combustion

Even though complete combustion occurs inside pellet stoves, some ash is still produced. This ash is collected inside an ashtray located below the burn pot. Since pellet stoves produce only small amounts of ash, homeowners don’t have to clear out their ashtrays more than a couple of times a week.

Room air is passed over the burn pot during the heat transfer process, which heats the heat exchangers. Once the heat exchangers are hot, this air must be exhausted because it contains toxins and dangerous gasses produced during combustion.

A blower is used to exhaust this unclean air into a piping system installed at the back of the pellet stove. The piping will then transfer the unclean air into a chimney or an exhaust pipe.

How Do You Vent a Pellet Stove Without a Chimney?

Pellet stoves don’t need a chimney to vent out exhaust air. If a chimney already exists, you can use it to exhaust unclean air. But if you don’t have a chimney, you can exhaust unclean air through a horizontal venting system.

A horizontal venting system is the most convenient and cost-effective way to exhaust unclean air from a pellet stove.

How to Install Horizontal Venting for a Pellet Stove?

Note: The following guide should be used to understand a typical installation process. Always hire an expert and follow the manufacturer’s installation manual.

Here’s a step-by-step process for installing a horizontal venting system for your pellet stove:

1. Secure an adapter at the back of your pellet stove.
2. Connect the vent pipe with this adapter.
3. Attach an adapter plate to a wall.
4. Pass the vent pipe through the adapter plate and ensure there are no leaks.
5. Ensure the vent pipe extends 6 in. (at least) outside of the exterior wall.

Here is an animation that demonstrates the whole process.

Horizontal Venting With a Rise

Homeowners should consider a horizontal venting system with a rise. This is preferable because natural heat convection exhausts the hot, unclean air if your stove stops working due to equipment failure or fuel shortage. The unclean air can filter back into your room if there is no rise in the vent.

Homeowners can build the rise in the venting system inside the building (directly from your pellet stove) or outside.

Before installing a horizontal venting system, it is important to consider the local building codes:

• Your exhaust should be at a distance from doors and windows; the specified dimensions vary in different building codes.
• Add a protector plate on your wall to protect against wall discoloring.
• Install the vent 3 ft. (minimum) above any air intake pipe (to prevent exhaust air recirculation.)
• Your exhaust should not interfere with a pathway.

Is a Cold Air Intake Necessary for a Pellet Stove?

A cold air intake is not mandatory for all pellet stoves, but installing a fresh air kit for all pellet stoves is preferable. Oxygen is important for proper combustion. A continuous supply of fresh air from the outside ensures that the pellets burn completely and evenly.

Certain building codes, as well as some pellet stove models, require a fresh air kit. If you’re unsure whether you should install a fresh air intake for your pellet stove, consult a professional.

Can You Vent a Pellet Stove Through an Existing Chimney?

A pellet stove can vent through a chimney. If you already have a chimney in your home, it will save you the hassle of cutting your wall or roof to pass a vent. But homeowners should take the following steps before venting a pellet stove through a chimney to ensure safety and efficiency:

Chimney Inspection

Hire a certified chimney sweep for a thorough inspection of your chimney. It will ensure that all parts of your chimney are properly working. If there are any broken parts or issues, such as creosote clogging, the chimney sweep will resolve them. You should only vent your pellet stove through a clean and properly functioning chimney to avoid the dangers of back-drafting or chimney fire.

The chimney sweep will also inspect the condition of your chimney flue. If your chimney flue is broken or missing, install a new one.

Also, install a chimney cap on top of your flue to protect it from rain, snow, and other environmental elements.

It is best to install half an inch of insulation around your chimney. It will keep the exhaust air hot, minimizing the possibility of creosote buildup.

Setting up the Pellet Stove

The chimney flue (liner) will attach to the back of your pellet stove through an adapter and extend up to the roof. The adapter must be clamped at the bottom end of the chimney flue and properly sealed using a fire seal. 

You will need to place the pellet stove inside the fireplace at a distance from surrounding walls and other objects. It will minimize the risk of nearby objects catching fire due to the radiation from the stove.

Once the pellet stove is in position, ensure the exhaust of the pellet stove is in line with the chimney flue. Then connect the two and make sure it is sealed properly.

If the connection is not sealed properly, the creosote can fall around the pellet stove and pose a fire risk. A secure connection ensures that the creosote falls into the stove, where it is burnt.

Hire Professional

Pellet stoves that come with manuals that have installation instructions. But it is best to hire a professional for the job. A certified chimney sweep will ensure that the seal is secure and that all clearances and standard practices are met.

And as a final safety check, get someone from the fire department to inspect the installation.

What Are the Dangers of a Pellet Stove?

Pellet stoves are safe heating appliances, especially since newer models have effective safety features. Still, homeowners must take precautionary measures and be vigilant when dealing with such appliances.

If you don’t take proper precautions in maintaining your pellet stoves, you pose the following dangers:

Improper Installation

Pellet stoves need to be installed with proper clearances from nearby walls and other items that can catch fire. If the stove is placed close to combustible materials, the radiation from the stove can start a house fire.

Reigniting Embers

Pellet stove fires are rare, but they still occur. Usually, it is because of improper installation or lack of precaution.

One of the most common causes of pellet stove fire hazards is the mishandling of ash. Ash produced by a pellet stove accumulates in an ashtray under the stove. This ash often contains live embers that can reignite when exposed to air, leading to disastrous house fires.

It is important to store the ash in an air-tight metal bin for at least one day before throwing it away. This will give it enough time to cool down, preventing fire hazards.

Lack of Maintenance

Your pellet stove needs to be regularly cleaned, maintained, and inspected by a professional. Lack of proper maintenance can lead to blocked combustion air holes that can cause a fire that can reach the hopper or the electronics.

It is also important to use quality pellets for your stove. Moist or poor-quality pellets burn slowly, creating a buildup of unburned pellets. These pellets accumulate under the burn pot and suddenly ignite, causing a blast inside the stove.

Chimney Fires

Pellet stoves produce relatively less ash and other toxic byproducts. But given enough time, creosote can build up inside your chimney. If your chimney is not regularly swept and inspected by a certified chimney sweep, the creosote buildup can clog the chimney and lead to a disastrous fire.

CO Off-Gassing

When wood pellets are stored, a chemical reaction occurs that produces Carbon Monoxide (CO.) The CO off-gassing of pellet bags is dangerous, especially since CO is hard to detect because it is colorless and odorless. Prolonged exposure to CO can lead to headaches, nausea, and even death.

That is why it is important to store pellet bags outside your home or building to avoid dire consequences. You should also install CO detectors where pellets are stored.

Can You Use a Pellet Stove as a Primary Heat Source?

You can use pellet stoves as a primary heat source. But not all pellet stove models are designed for this purpose. Usually, you’ll find pellet stoves that are used to heat a single room.

Since different types of pellet stoves are designed for different purposes, let’s find out which is best used as a primary heat source:

Freestanding Pellet Stove

The most common type of pellet stove is the freestanding pellet stove that is designed to heat the room they’re installed in. Freestanding pellet stoves provide heat by blowing hot air into the room.

While some heat may dissipate into other rooms, it would not be enough. But if you have an open plan house, installing a large freestanding pellet stove with sufficient output can heat your entire house.

Ducted Pellet Stove

If you plan to use your pellet stove as a primary heat source, a ducted pellet stove can be a viable solution. Ducted pellet stoves provide heat by blowing hot air, as do the freestanding pellet stoves. The difference is that a network of ducts is installed, which convey the hot air into other rooms.

The difficulty with ducted pellet stoves is that they need to be customized according to your house plan. Another problem is that they’re not optimum for heating larger houses because the heat can travel up to a certain distance away from the stove.

Hydro Pellet Stove

A hydro pellet stove or pellet boiler looks like your typical freestanding stove, the only difference is that it does not have a vent at the front. That’s because the stove is connected to your central heating system from the backside.

These stoves offer a clean, efficient, cost-effective alternative to gas boilers for central heating. The only downside is that it’ll take more time to heat your house than a gas boiler.

Can a Pellet Stove Heat a Two-Story House?

A pellet stove can be used to heat a two-story house. But where you install the stove will decide how efficiently it will heat your house. For best results, place the pellet stove near the stairs of your basement. Since heat rises, setting it on a lower floor will heat the rest of your house. The basement will not get warm if you place the stove on the ground floor.

Here are some other things you need to consider:

• It’s essential to decide on the right kind of pellet stove system, depending on the layout of your house.
• For an open concept layout, a freestanding pellet stove with sufficient capacity should be great.
• If you’ve got a sectioned layout with multiple rooms, a better choice would be a pellet stove that connects to a ducting system.
• You also need to factor in the living space; generally, a unit producing 60,000 BTU can heat a 2,000-square-foot space.
• If you live in colder climates, your heating unit will need to produce more heat to meet the required temperature.
• The same is the case with a house with poor insulation. Some of the heat will dissipate out of your home, so your pellet stove will need to work more to cover the losses.

With all these factors at play, it can get complicated for a homeowner to decide. That is why it’s best to hire a professional to guide you through the process.

Pros and Cons of Pellet Stoves

Now that you’ve got a comprehensive understanding of pellet stoves and their various types, it’s time to weigh the pros and cons to see whether it meets your needs.

The Takeaway

Pellet stoves present a cheap and clean heating solution for your home. You don’t even need a chimney for a pellet stove. But if you already have a chimney, you can install a pellet stove inside the fireplace and use the chimney to vent out the exhaust gasses.