You’re likely reading this because you are cold and not satisfied with how well your current wood stove is working. But what you really need to understand is about maximizing the efficiency of your wood stove, as it applies to the building you are trying to heat. Lets keep that in mind as we explore all the tips and tricks to keep you warm, all while using the least amount of fuel possible.
Of course, knowing how to get the most heat from a wood stove and mastering it’s efficient operation not only keeps you warmer for longer, but is cost effective too. Many of the tips you’ll find here are easy to implement and won’t break the bank.
If you haven’t yet bought a stove or you are looking to replace your stove, purchasing the right wood stove can make all the difference. Some of this article will explain many aspects of choosing the right stove so pay attention.
If you already have a wood stove and have been operating it for years, that’s OK too, the rest of this article might just give you some great ideas you haven’t previously though of to get more out of your wood stove.
We can categorize these tips as such, efficiency value add tips, fuel tips, maintenance, operation, and design specifications, (feel free to skip to the content that interests, you the most, but putting it all together will give the best results);
2. Increasing thermal size
3. Using fans to move the air
4. Ducting heat from wood stove
5. Reduce heat loss through building insulation
6. Heating the house in stages
7. Use the right type of wood
8. Quality of wood
9. Keeping the flue clean
10. Keep the fire box clean
11. Keeping seals in good order
12. Ensuring door is tight
13. Ensuring stove vents operate smoothly
14. Monitoring temperature
15. Maintaining correct fuel levels
16. Maintaining correct air flow
17. Correctly sized wood stove
18. Design technology advancement
19. Straight Flue design
20. Its all about air flow
Grab yourself a cup of something warm, there is a lot of tips to get through here.
Wood Stove Efficiency Value Add Tips
This tip is perhaps not directly related to the wood stove, but will have a significant impact on the efficiency of your wood stove operation.
We already talked about positive air pressure, but this works only up to a point where there is minimal drafts in the house. A wood stove drawing external air can never create enough positive pressure inside the house if an external door left open.
So assuming you have closed all the external doors, what’s next. Drafts in the house will allow cold air in, which requires more heating output from the wood stove to compensate.
Drafts will come in from around natural openings such as doors and windows.
All the below tests are best performed when the wood stove is lit and the house is warm, and it is cold and blowy outside, as this will help create the biggest draft or temperature difference.
a) Use a digital infrared thermometer is the quickest method, and gives you the best reference for which drafts are excessive and need to be tackled first.
Point the thermometer are various surfaces in each room to establish a base line. Then point and move the infrared thermometer around the entirety of the closed window and door edges. If you see a significant temperature difference (more than 3 degrees Celsius, or 6 degrees Fahrenheit) to the ambient temperature in the room, then that is an area allowing cold air in or warm air out.
b) Another way to find draft leaks is using the smoke from an incense candle. Incense candles produce just the right amount of smoke for this to work well.
Light an incense candle position it close to window and door gaps. Start at the top of the door and window so that the smoke does not naturally flicker. Slowly move the candle along the top gap of the window and then down each edge before finishing along the bottom edge.
If you notice the smoke changes direction, either towards or directly away from a gap that’s an air leak.
c) The same principle as the incense candle can be applied by using a flame such as with a lighter or standard candle. We don’t recommend this method simply because it uses a flame, so we won’t go into too much detail, I’m sure you can use your imagination to see how this method is used, but just make sure to watch out for light weight window dressings and flames.
d) Lastly you can use a small piece of tissue paper. Tear or cut a strip of tissue paper approximately 150mm by 50mm or 6 inch by 2 inch. Hold the tissue paper at the top and slowly move along the window or door gap as before. Because the tissue paper is so light it will react to breeze through gaps.
Here’s our best tips for plugging drafts in doors and windows
- Install New Door Sweeps (aka weather strips) at the base of all doors. (Expert tip, check for deterioration and replace every few years). (Expert tip # 2, install in interior doors that are usually closed when heating, such as laundry, bathrooms, and basement).
- Hang Insulated Curtains over all windows (Expert tip, make them close fitting and also install closed pelmets).
- Use a Door Snake (aka Door Draft Stopper) under all doors.
- Apply insulated window film to all glass areas.
- Replace light weight external doors with solid wood. (Expert tip, make sure external doors don’t have glass panels).
- Install foam insulating tape around window and door frames.
Dense materials such as clay bricks soak up lots of heat, and retain that heat for a long time. This can be used to our advantage by keeping room temperature more constant for longer periods of time.
You can stack clay bricks next to the wood stove. The bricks will heat up over time due to their close proximity to the wood stove. The bricks will continue to radiate heat for many hours after wards, so even when your wood starts to run low after an overnight burn down the brick will still be radiating some heat.
There are many wood stove fans on the market, specifically designed to sit on top or attach to a wood stove. But there are other ways to use airflow to your advantage.
As you know hot air rises, but air can also be pushed in a direction and pulled towards low pressure areas. So you can setup some gentle airflow in your house to pull down the hot air that gets trapped in the top half of the room (on the ceiling) by placing floor mounted fans at far ends of a corridor and directing airflow towards the wood stove.
This will help push cold air towards the wood stove where it can be heated and simultaneously draw down the hot air where it can be used to heat the lower half of the room.
Additionally turning on ceiling fans will help push hot air down to the lower half of a room as well.
Consider installing ceiling fans in high ceiling areas that would otherwise trap unused warm air.
Borrowing from the last two ideas you can also take warm air from near the wood stove and pipe it to colder areas of the house.
Setup a open ended pipe (made from non flammable material) next to the bricks (or attached directly to the wood stove if you can find the right fitting such as a heat reclaimer). Run the pipe from the wood stove to a cold area of the house. Place a small fan at the end of the pipe and fan the fan so it blows out of the pipe.
This will draw warm air from the wood stove and slowly warm the cold areas of your house.
Warning, there are dangers with connecting a wood stove to ducting installed through a house, we recommend you control a HVAC specialists before attempting this.
Depending on the construction materials used in your home, heat can be lost very quickly or retained to maintain comfortable temperature levels all night.
The biggest benefit for most house is to insulate the roof, which can be done relatively easy with reflective roof insulation materials.
The next area to address heat loss is through windows, adding insulation film and insulating curtains can work well.
The last major heat source of heat loss is through walls, which can be much more tricky to insulate. Best to consult a professional to get a quote if your looking at doing that.
Simply put, when starting a fire, try and heat the parts of the house where you are spending all of your time first.
Close off rooms that are not occupied at least until the room temperature starts to rise to a comfortable level. Close bedroom and bathrooms, laundries etc. Trying to heat too much of the house too quickly is a sure fire way to burn through too much wood fuel.
Once the fire is well lit, maintaining temperature through every room in the house can be a great efficiency tip. If for example you close off a laundry, all the time. There will be some point in time that you need to go in there. That’s when a large amount of cold air will rush in and need to be heated. Opening up all the house rooms will heat up the building structure where heat soak will then help to stabilise the temperature and keep the whole house warm for longer.
Wood Stove Fuel Tips
Starting a fire is easier if using softer woods. Soft wood has lower energy density that hard wood but fire catches hold more quickly, so soft wood is great for building a base and getting a fire started.
Hard woods are better for burning longer and can have significantly more energy to be released when burnt.
Meaning that once a fire has started, loading the fire box with hard wood will be must easier to maintain a higher and constant heat for much longer than softer wood.
Consider using manufactured compressed logs as they hold an increased amount of BTUs, and are great for long overnight burns.
High quality wood is simply wood that has been seasoned. Seasoned wood is a term used for dried wood.
Seasoned wood has been cut and stored for a season (usually the months of the year your wood heater is not operating), which has the effect of drying it out.
Seasoned wood has a lower water content thereby allowing the wood to burn cleaner and hotter. There are some tricks to make sure you season the wood correctly, including covering, storing off the ground, splitting before storing, stacking arrangement, and allowing air flow.
Good Wood Stove Maintenance Practices
Too much smoke will start to constrict your flue as the smoke particles gather and cling to the inside, thereby gradually reducing efficiency over time.
You can think of excessive smoke as a bit like fatty plaque deposits in arteries causing a heart attack. If the flue contains rough deposits these will slow the air flow. Additionally soot deposits stuck inside your flue will effectively reduce the flue diameter further reducing air flow.
So, just like you don’t want a heart attack, neither does your stove.
Unimpeded air flow is essential. Old ash from fully burnt logs needs to be removed before often.
If you live in a climate that requires the fire to be constantly lit, this is a bit trickier than if you can restart a fire each day.
Ash from a constantly lit fire will need a bit of caution for its removal. Best option is to remove the ash each morning or when the fire has been left for an extended period of time and is at its least intense (coolest).
Carefully shift the remaining un-burnt wood aside making sure you do not smother the un-burnt coals. Using a steel fire shovel scrap the ash into another area and scoop into a steel bucket. Remember the ash is hot so use a bucket with a handle and make sure the bucket is not resting on a floor surface that is flammable or easily marked.
We just can’t say this enough, efficiency of wood stove design is all about airflow. When an engineer designs a wood stove they are thinking about adding air at certain points through the clever direction of air flows ensuring the best burn.
A firebox that isn’t properly sealed as per its intended design could allow air to enter that disrupts the intended firebox air flows, potentially reduced secondary burning.
We recommend checking wood stove door seals before each season and budgeting for replacing the door seals every other season.
As previously stated keeping the door closed ensures the correct firebox air flows will be maintained.
It is OK to open the door when starting a fire but once its going let the stove design take over and trust that adding air by the inbuilt vents is more effective.
It will certainly help with keeping smoke from escaping from the door.
Once the wood is burning well adjusting a wood stove can be thought of in the mold of “less is more”. Don’t establish a habit of frequent adjusting, this takes practice but you will get there.
Having said that, there will be times when you do need to adjust the air vents to optimise the air flow. Wood stoves have to deal with high heat so air vents are usually simple designs, complex and high heat that warps metal isn’t a good combination.
Simple designs usually means that air vents don’t always operate smoothly. Ensuring the air vent controls are free from debris and damage offers the operator more finite and therefore smooth adjustment of the air vents.
We recommend when cleaning out ash from the fire box running a quick check of the air vents to ensure smooth operation, and a quick clean if necessary.
Note, do not spray with any lubrication (yes some people not thinking about flammable liquids will do this), its dangerous. A quick wipe over and moving parts with a clean dry rag should be all that is required.
Wood Stove Operational Tips
These days with technology advancements wood burning stoves can automatically adjust their heat output to a preset temperature. But you can just as easily do this yourself with a standard room thermometer.
Using a thermometer can sometimes stop disagreements when different people are feeling warmer or colder, a quick reference of the thermometer can confirm a normal temperature range. This also happens often when someone comes in the from the cold and they want to turn up the heat as their normal “feel” for room temperature is out of balance due to cold exposure, and other times they think they will warm up quicker.
The down side to frequent adjustment to balance room temperature is that this often gets the fire burning quicker, and using more fuel than necessary.
And here’s a big don’t. Don’t keep opening the door, this reduces so much heat a takes a while to recover. Your wood stove is designed to operate with doors closed. If you want the best performance, once the fire is going, only open the doors to add more wood.
Once the fire is going well, maintain the wood levels. Don’t let the fire burn down all of the wood, but also don’t overload, as this can overheat and become a very dangerous situation.
Additionally, over filling will just consume more wood than necessary, and if you are reading this, that’s not your goal.
This point is where we need to realise that the term efficient is a relative term. It relates to what you want from your wood stove at that moment in time. You might want to maintain a room temperature because that’s the part of the house you are living in, but you might want to just keep the chill at bay over night.
Its usually only with practice that you can set air flows for either consistent warmth, are for longer overnight burns.
Best advise here is to use the thermometer, practice, and watch and learn.
Many stoves have more than 1 air flow vent, a primary and secondary is common in newer stoves.
The primary vent allows lots of air in to get a fire started. Lots of air equates to lots of flame, or a larger flame. Big flames are ideal for starting a fire but not necessary for maintaining a burn once the fire box is up to temperature.
When starting a fire, all air vents should be wide open. Read your specific wood stoves operational manual to confirm.
Once the larger logs are in the fire and have caught this is the time to start slowly closing the primary vent. You will notice the flame size will drop and it will appear that the flames also slow down. Low and slow flames are a sign that your fire is starting to operate the highest efficiency range.
Once the primary vent has been closed down finer control can be achieved with the secondary air vent lever. Best way to operate the secondary air vent is to monitor temperature with a thermometer. Make small adjustments then wait, temperature changes in a room take some time, so don’t make changes before the stove has time to catch up.
Note, aftermarket damper plates are available and usually cheap. These can be installed in your flue to control airflow and trap heat in.
At various times you will need to reload wood. Best way to do this is place more mood on the fire and do not adjust the vents at all. If the fire box still has enough heat the new logs will catch fire so enough. If you waited too long to put more wood on the fire you may need to open up the primary vent to help the log catch, and start all over again. This often happens after and overnight burn down.
Wood Stove Specifications Tips
17. Make sure your stove is correctly sized, and has the right heat output, for the area you are trying to heat
It might sound obvious but a stove that is too small just wont keep up with a large area to heat. A wood stove that is too small will consume lots of fuel and struggle to keep the area warm.
But its also just as bad and perhaps less obvious for a stove that is too large or has too high a heat output for the area.
A wood stove that is too large will be difficult to control because you will usually be trying to keep it burning cool. Slow or cool fires usually produce a lot of smoke.
There is also a consideration to be made for the climate, deep cold winters will require a wood stove that is higher rated than areas with short and mild winters.
Many later model wood stoves have incorporated technology advancements in recent years.
Some of these technology enhancements include,
- material coatings such as ceramics,
- electronics to adjust air flows and automatically maintain constant temperatures,
- multiple combustion chambers where air is added at different stages to burn gasses not burned in the primary combustion cycle,
- clever air flows that can blast air at the fire and effectively “wash” the glass,
- pellet stoves, that use carbon neutral and very efficient fuel.
- heat reclaimer or heat exchanger mounted in the flue.
If you are looking at upgrading to a new wood stove, consider what technology best suits your needs and budget.
A good flue design is paramount to the performance of any wood stove.
You can think of a flue a little bit like the engine in a car, without an engine the car cannot make power, the power in a flue is up draft.
As we all know hot air rises, and as it rises it creates a draft, the hotter the air the faster the draft. The draft draws in air through the wood stove air inlet vents, therefore pumping air into the fire, the more air a flue can flow the hotter the fire can get.
Considerations of flue design;
- diameter matches the wood stove outlet diameter,
- most of the flue is inside the area to be heated, as the flue gets hot it will radiate that heat into the room,
- if a hotter air creates a faster draft then it stands to reason than an insulated flue that reduces heat loss will effectively be a bigger pump and be able to flow more air,
- bends in the flue will reduce airflow so avoid bends, make your flue as straight as possible,
- if you have to install bends (such as if going through a wall) then install a T section with a cap on the outside wall, this will make cleaning so much easier.
Its all about air flow. As we discussed above with flues airflow is critical. The flue drives the air flow but the air has to come from somewhere. It doesn’t make sense to warm up the building and then use that warm air to fuel the fire and send it up the flue. The best solution is an air inlet vent that is external to the building bringing in lots of fresh air.
A short inlet pipe, sucking air external air, with no bends, and matched to the diameter of the inlet port of the stove is ideal.
An additional benefit of external air supply is reducing drafts in the house. When the flue is drawing air through the fire and the air is coming from out side the heat radiating from the wood stove create a small positive pressure inside the house, (assuming the house is mostly air tight), this positive pressure is just slightly above the outside air pressure. As air will flow from high pressure to low pressure areas this will reduce a draft from entering the house.