Your wood stove is not getting hot? In this article, we’re going to check the most common reasons and ways to fix them.
After reading this article, you will know exactly how to get your wood stove as hot as you need it to be!
You will know exactly what to do and why.
Quick answer: A wood stove usually does not get hot because of an insufficient oxygen supply. You can fix this by opening the air intake valves and cleaning the burning chamber, the vents, and the wood grate. Also, make sure that you use seasoned firewood. Also, verify that your chimney’s diameter fits your wood stove size. You can maximize chimney airflow with a chimney liner.
Let’s have a look at all of the different reasons and ways to fix each of them!
Reasons and fixes for a wood stove not getting hot
Almost all heating issues with wood stoves are in some way related to insufficient oxygen supply.
The wood in your wood stove needs oxygen to burn efficiently. Without or with a lack of oxygen, the wood burn is very inefficient, meaning you get very little heat out of it.
Also, a lack of oxygen always causes the production of carbon monoxide and other toxic gases.
So, getting the right amount of oxygen into your wood stove is crucial!
There’s no single way to test a lack of oxygen in your wood stove. Since there are multiple possible issues that cause a lack of oxygen, you have to test multiple things:
1. Air intake valves closed
Wood stoves usually have between one and three air vents. Each of those vents is responsible for opening and closing airflow into your wood stove.
Usually, one vent opens the airflow into the bottom part of your wood stove. Sometimes, when you have a second or even a third vent, then these are responsible to supply the sides or the top part of your wood stove with oxygen.
How to test: You can adjust the air intake with a small lever or knob (that you pull or push), one for each air valve.
Open all of your air vents. If your air vents were closed before, and you didn’t even know that they existed, then here’s your fix!
How to fix: Before lighting a fire, always open up all of the air intakes. When your fire burns brightly, you can lower the air intake to force a slower burn.
2. Airtight room
Wood stoves exhaust waste gases out of the chimney. This creates a suction that is used to pull new and fresh air into the wood stove.
Now, imagine your room is fully sealed and no air can enter it. Then, your wood stove would not be able to suck in any air.
To be physically correct: Your wood stove would be able to suck in a bit of air from your room. But, since this air is now missing in your room, the suction creates a negative pressure in your room.
The negative pressure would build up until the suction from your wood stove can’t overpower it anymore.
Then, the fire would extinguish.
Real-life rooms are never perfectly sealed. Every burning wood stove is proof of a room not being perfectly sealed.
There are always gaps and cracks below doors and millimeter openings in windows that allow air to enter your room.
If your room is airtight, then you won’t be able to heat it.
How to test: Light your wood stove. See how it burns. Then, open your window and see if the burn improves. If it improves, then your room is too airtight for your wood stove.
How to fix: Usually rooms are not airtight unless someone (you?) tries hard to insulate it.
The first thing to look at is the gap below your room’s door. Is it wide enough for air to pass it?
Even a millimeter should be enough. But if you use a door draft stopper, that’s what might be the reason. Rubber draft stoppers are worse than fabric or sponge draft stoppers, which allow a bit of airflow.
Remove all this additional air insulation from your room and see if your wood stove burns properly now.
3. Clogged air vents
The third reason for a lack of oxygen in a wood stove is the lack of airflow below your wood.
Merely opening the air intake valves does not guarantee proper airflow into your wood stove.
Your air vents could be clogged with ash.
Also, make sure your wood stove pipe is not clogged! For this, you can use a large wood stove pipe wire brush!
How to test: Check the air vents of your wood stove. Do they allow airflow? You can test this using a wire brush. Push it through the air vent and see whether ash comes out of the other end of the vent.
How to fix: Clean all of the air vents with a wire brush. Use a large wire brush for the stove pipe.
4. No wood grate
Also, make sure that your wood grate is clean. The wood grate is the metal grid on which you place the wood.
And, of course, don’t forget to use a wood grate in the first place! Pre-built wood stoves usually have a wood grate. But if you built your own stove, then you have to get a wood grate that fits it!
How to test: Have a look at the inside of your wood stove. Is there a grate on which you put your wood? If yes, is it clean and does it allow airflow below the wood?
How to fix: Clean your clogged grate. If you don’t have a grate yet, then build this US stove grate (click here to view it on amazon) into your stove. For larger barrel stoves, use this barrel stove wood grate (click here to view it on amazon).
5. Heat escapes through pipe
Fire burns with temperatures up to 2,000°F (1,100°C). Also, heat is energy. And energy does not vanish.
If there’s a fire burning in your stove and it’s not getting hot, this means that the heat leaves somewhere.
The most likely heat sink in your wood stove is the pipe. And you can’t really do much about the pipe.
You need it because the pipe is an exhaust path for the smoke. And the pipe supports the air circulation inside your wood stove.
So, we don’t really want to change anything about your wood stove pipe. But why does the heat leave through the pipe then?
The air passing through the pipe has to be hot. The reason is that hot air rises faster through the chimney, which helps suck more air into the stove.
So, it’s expected that heat escapes through the pipe.
How to test: You can verify that heat escapes through your wood stove pipe by touching the pipe. Be quick and careful! Wood stove pipes can easily get as hot as a frying pan.
How to fix: You can’t really fix the heat escaping through your wood stove pipe. Some heat always has to leave to draw fresh oxygen-rich air into the stove, which, in turn, enhances the burn.
However, if you think that your wood stove pipe gets way too hot, then you can absorb a part of the heat by wrapping a copper (or any other metal) duct or wire around the pipe. The metal will then absorb the heat from the pipe and radiate it into the room.
I think, however, that this is a waste of money, since the heat absorption improvement is only marginal. Additionally, it makes your wood stove look ugly.
And, worst of all, because the DIY heat reclaimer absorbs heat from the exhaust air inside the pipe, the exhaust air rises slower, which reduces the amount of air that is sucked into your stove.
So, trying to fix a too-hot wood stove pipe is a zero-sum game and not worth it.
6. Chimney diameter is too large or too small
All of the exhaust air leaving your wood stove goes through the chimney. The design of the chimney is crucial for a proper wood stove burn.
For example, wide chimneys are good for large wood stoves and fireplaces. Narrow chimneys are good for small wood stoves since they increase the rising velocity.
Similarly, long chimneys cause a higher hot air rising velocity than short chimneys.
It could be that your wood stove does not get hot because the chimney does not fit the wood stove’s size.
How to test: Theoretically, the best test for this would be to test your wood stove with a different chimney. And to test your chimney with different wood stoves. However, that’s not practical.
You can’t really know exactly which chimney and wood stove combination fits unless you consult a technician. Where I live it’s mandatory to get a professional’s approval before installing a wood stove.
But that’s not the case everywhere. So, if you did not get formal approval for your wood stove, I’d recommend checking your heater’s heating capacity and your chimney length and diameter.
Then find out online, or by consulting a professional, whether your setup works or not.
How to fix: If your wood stove and chimney combination does not work, you can usually fix it using a chimney liner.
A chimney liner is an insert for your chimney to narrow your chimney’s diameter. A proper chimney liner maximizes your wood stove’s burning efficiency and helps with proper airflow.
However, they are usually very expensive (well above >$1,000), and you usually need to hire someone to do it for you.
If that’s not an option for you, continue with the next tips!
7. Wood stove has a large heat capacity
Some materials take longer to heat up than others. Also, two objects of the same material, but of different masses will have different heat-up times.
Some wood stoves are made of different materials than others. And some wood stoves are heavier than others.
That’s why it’s perfectly normal for some wood stoves to take very long to heat up.
The wood stove in my home heats a lot faster than that of my grandparents.
A lightweight (if we can ever use that word in combination with wood stoves) metal wood stove heats up quickly. Its walls are solid, but relatively thin metal. Metal is a great heat conductor. You can feel a metal wood stove heating up within 10 minutes.
On the other hand, a large wood stove, built of metal and heat-absorbing stones will take longer to heat up. After starting the fire, the heat first has to heat up the stone slabs before it reaches you.
How to test: Your wood stove usually has a small heat capacity, and, therefore, heats up quickly, if it is plain metal.
However, if your wood stove has natural stone plates attached to it, which absorb the heat, then it will take a while to heat up.
How to fix: There’s nothing you can and should do about it. To change your wood stove’s heat capacity, you would have to add or remove parts of it, which makes no sense.
Just be more patient!
8. Stove too large for room
Stoves (and all kinds of heaters in general) have to fit your room size. You can’t heat a large room with a small stove. And accordingly, using a large stove in a small room rarely makes sense.
The main issue with large stoves is their heat capacity which causes a long heat-up time (as we’ve seen in the previous section).
How to test: You can check your stove’s manual and data sheet to see the room size it is designed for.
How to fix: Use a smaller stove in your small room.
9. Wet wood
Fresh wood outputs a lot less heat than dried and aged wood. The reason is the water content in fresh wood.
For a proper burn, you don’t want water to absorb the heat energy continuously. A fresh piece of wood has a moisture content of 70%.
This means for each pound of dry wood, there are 0.7 lbs of water.
A wood stove fire, therefore, has to provide enough heat to keep the fire going brightly and evaporate 0.7lb of water!
Additionally, the gaseous water rises out of the chimney.
That’s a lot of energy being wasted here!
So, always use as dry as possible wood! There’s a reason that burning coal (which is practically the same as wood with 0% moisture content) can melt metal, and fresh wood can’t.
How to test: Instead of using the potentially wet wood you have at home, buy dried wood at a store once. I know, it’s overpriced, but you have to do it for the sake of the experiment.
Ignite the store-bought wood and see if there’s a difference. If the fire burns properly now, you got the reason!
How to fix: Pile your wood in a dry place. Ideally, don’t cover it under a plastic cover (which would increase humidity), but keep it under a roof. If you don’t have a dry place for your wood, then build one. It’s well worth it!
Dry your wood for 1-3 years (depending on the climate you live in).
If you don’t have a supply of dry wood right now, buy dried wood for the first few seasons and let your own wood dry in the meantime.
“There is no danger in over-seasoning wood – drier is better.”
Forest Products Center tennessee.edu
Also, you can check your wood’s moisture content using this moisture meter (click here to view it on amazon). Your wood is ready when its moisture content is below 20%.
10. Outside air too warm
A wood stove can only burn properly if an air draft constantly fuels the combustion. For a proper air draft, one of the factors is the outside temperature.
As you probably know, hot air rises above cold air. That’s why your wood stove’s exhaust gases go out of the chimney in the first place.
But there’s another detail: The greater the temperature difference between the wood stove waste gases and the outside, the faster the hot gases rise.
This means your wood stove will have a stronger suction on very cold days than on warm days.
So, if the outdoor temperature is mild, this might be one reason for your wood stove not getting hot.
It’s very likely that it is not the sole reason. The hot waste gases going up the chimney are always significantly hotter than the outdoor air. They are usually between 300°F and 480°F. So, a change in outdoor temperature of +20°F would not affect the draft much.
A 20°F outdoor temperature increase would decrease the draft between 4.1% and 6.7%.
So, while it is never the sole reason, the outside air being too warm can be a factor.
How to test: Check the temperature outside. Is it significantly warmer than on other days?
How to fix: To compensate for the draft decrease you have to open the air intakes up more. If they are already fully open, you can also increase the air intake by opening the wood stove door a bit.
11. Wood stove fan or blower
Stop using wood stove fans or wood stove blowers! Wood stove fans and blowers are small devices that blow the hot air from the wood stove into the room.
A wood stove fan absorbs the heat from the stovetop or the stove pipe. Then it converts it to rising air and uses the kinetic (movement) energy from the rising air to rotate a fan. The fan then blows the warm air into your room.
A blower usually does the same thing, but it is battery-powered.
While the idea of a wood stove fan sounds good at first, it turns out to be a complete hoax. And they can even harm your wood stove.
Wood stove fans absorb the heat from your stove. This means that your stove (and the hot gases in it) miss this heat energy.
In turn, the hot waste gases going up the chimney have a smaller temperature. And “cold” waste gases don’t move up the chimney with force.
This means they don’t create enough pull to draw more air into the wood stove. This, in turn, hinders the fire inside the wood stove to burn properly.
How to test: Check if a wood stove fan stands on your wood stove. Also, check the wood stove pipe for a fan. It does not even necessarily need to be a fan. Anything that absorbs heat from your wood stove is bad.
It could be a coil wrapped around your wood stove pipe. Or it could be a metal structure that absorbs heat in any other way.
How to fix: Remove any object that prematurely absorbs heat from your wood stove.
12. Dirty inside
Even if your wood stove’s air intake is good, the dirt and ash in your wood stove’s burning chamber could prevent it from getting hot.
Ash and creosote insulate the inside of your wood stove. They don’t prevent the fire from burning.
Even worse: Ash and creosote sticking to the walls of your wood stove can increase the amount of heat trapped inside your wood stove.
This can increase the heat inside the wood stove. But, accordingly, it reduces the heat outside the wood stove.
While it is very unlikely that the ash and creosote in your wood stove insulate the heat completely, it is another factor that can reduce the heat your wood stove gives off.
How to test: When your wood stove is cold, draw your finger along the inside wall. Is there a layer of ash and dirt? If yes, how thick is it?
How to fix: In any case, clean the inside walls of your wood stove. Also, to prevent dirt buildup in the future, I recommend cleaning the inside walls of your wood stove once every two weeks during the heating season.
What to do if your wood stove is still not getting hot?
If, after checking all of the potential causes of your wood stove not getting hot, your wood stove is still not heating properly, I’d assume that something is critically wrong either with the wood stove or the chimney.
So, I recommend checking the chimney. Verify that your chimney is free of any obstructions. Did a cat fall into it? Or is it clogged with fallen leaves from autumn?
A seriously clogged chimney is unlikely, but if your wood stove still does not get hot, then that’s something you should double-check.
If your chimney is OK, and you still have no idea why your wood stove is not working, I would recommend consulting a chimney sweeper.
Alternatively, if you suspect your wood stove is trash (because you bought it who knows where), then throw it away and buy a new one from a stove company nearby. Let them install it. If it doesn’t heat properly, they will figure it out!
Conclusion
Almost all wood stove problems are caused by a lack of airflow into the stove.
There are many things that cause a lack of airflow. It could be a bad design of the wood stove, a too-wide chimney, and an overly dirty burning chamber.
Also, it could be bad wood. Only use well-seasoned dry wood!