Pellet heaters might pump out real heat, but you need to make sure you pick the right sized pellet heater for your home. Picking the right sized heater is essential if you want to stay warm during winter and maximise efficiency of the heater. If you’ve looked at any other posts on my website you’ll see pellet heaters range in heat output from about 6kw to 13kw. So if you want to know how to size a pellet heater correctly, read on as below I take a look at what you need to consider when deciding on what type and size pellet heater to get to heat your house.
Here’s a quick guide to what sized pellet heater to get depending on the area you want to heat. It’s very simple and more info is provided below, so I encourage you to keep reading:
- 6kw pellet heater for one room less than 80m2 or tiny house
- 9kw pellet heater for large room 80m2 or bigger and taking chill off other rooms
- 13kw pellet heater for large room and want to warm rest of house as best as possible
Room Size
First, how big is the room or area you want to heat with a pellet heater? To calculate this just take the length of one wall, the length of another wall (I’d pick the two longest walls if they are different lengths) and multiply them together. The longest walls in my lounge are 6 metres and 5 metres, so my lounge is about 30m2. That’s not exact because it isn’t a square or rectangle in shape, but it’s close enough. Once you know how big the room is then you can start to calculate what size heat output pellet heater you need.
Quick and Dirty Heater Size Calculation
A very rough rule of thumb is for every m2 of space you need 100 watts of heat from any type of heater. So, if your room was 30m2 then you’d need 3000 watts or a 3 kilowatt maximum heat output heater. Keep in mind this is a VERY basic, quick and dirty way to calculate heater size. At the bottom of this page I will include links to websites that provide much more detailed calculators, they take insulation, ceiling height, single or double glazed windows into consideration, which will give you a more accurate calculation.
However, using this method I’d need a pellet heater that can put out around 3 kilowatts of heat. The minimum heat output on most if not all pellet heaters is 3kw. This is why in many posts I say most of the time a pellet heater will be running on low heat, around 3kw. There will be very few cases where a common house in Tasmania or even Australia will have a pellet heater running on high all the time. If your lounge is 80m2, then you’ll need a pellet heater that can put out around 8kw.
Sizing a Pellet Heater to Heat a Whole House
OK, so using the quick rule above you know you might need a 8kw heater for an 80m2 lounge room. However, what if you want to keep the rest of your house warm? This gets a bit tricky because it depends on the layout or design of your house. If you live in an open plan house, then I would simply do the trick above, two longest walls of your house and use that. So if your house was 10m by 10m, then thats 100m2 or a 10kw pellet heater. If it was 150m2 then you’d want around 15kw pellet heater, which they don’t make so a 13kw would be good enough.
If you don’t have an open plan house, then it’s not so easy. Heat, even if you use a fan to help distribute heat from a pellet heater, will get trapped in hallways and rooms. This applies to any type of heater, not just pellet heaters. As I mentioned elsewhere, the best way to heat a whole house with a pellet heater is to position it somewhere that is central and connected to the rest of the house. In this case I’d look at the size of the room the pellet heater is in and go a model up.
Example, if the lounge room was small and only 30m2, you’d need a 3kw pellet heater. The smallest models put out a maximum of 6kw of heat, which would work fine if you only wanted to heat the lounge room and nothing else. But if you are wanting to heat or warm the rest of the house, then I’d go up to the “medium” sized pellet heaters which do about 9kw of heat. Again, your pellet heater won’t be running on high all the time but the extra heat output will help warm the rest of your house.
Other Pellet Heating Options for a Large House
You can see that while pellet heaters can heat a house there will be a difference in temperature between the rooms. This is because pellet heaters, like wood heaters and heat pumps, are space heaters. They are best at heating a single area. They will heat other rooms and your house but the heat will not be evenly spread throughout the house. If you want to control the heat in other rooms or have an even heat in your house then you need to get a hydronic pellet boiler.
Pellet boilers are basically central heating systems. They burn pellets just like a pellet heater heat water which is then pumped around the house to heat rooms. They come in much bigger sizes, ranging from 18kw the smallest to 50kw the biggest. In Tasmania the Sampson hydronic pellet boilers are popular and come in two models: a boiler and space heater or just a boiler. The space and boiler models heat the room they are in, like a normal pellet heater, with hot air but also create hot water that is pumped to other rooms. If you want total control over how your house is heated then you need a hydronic pellet boiler.
Different Sized Heater Models to Consider
OK, so you know the size of the room or your house and have a rough idea of how many kw pellet heater you need. Here are some models to consider. You can buy these pellet heaters in Tasmania but I also have a page dedicated to buying a pellet heater if you don’t live in Tassie.
Small Sized Heat Output 6kw
If only looking to heat a small room or don’t need much heat, I’d check out Pellet Fires Tasmania or Tas Energy and Heating if you are in Tasmania. PFTas sell a Matilda or Mini which would be fine. Both of these pellet heaters do about 2.7kw to 6kw maximum heat, which would be fine for a small area. Tas Energy and Heating sell Piazzetta pellet heaters and the Carol is a 6kw sized model, again more than enough heat.
Medium Sized Heat Output 9kw
If you have a very large lounge and or want to take the chill off the rest of your house, then in Tasmanian again PFTas and also Bass Pellet Heaters in Launceston have mid range pellet heaters that fit the bill nicely here. PFTas has the Midi 9kw and Bass has the Bass 02 pellet heater. Tas Energy and Heating also has a range of heaters that are around 8kw to 9kw, with the P920T being the most affordable.
Large Sized Heat Output 13kw
Want heaps of heat and or have a very large room or house to warm then you definitely need something in the 12kw+ and high range. All retailers in Tasmania have you covered here. PFTas has the popular Grace 13kw pellet heater and Bass has the Bass 09 pellet heater. Bass is 12kw but you honestly wouldn’t notice the difference. If you want something with a little European style and are happy to pay, Tas Energy and Heating sells the P943M pellet heater.
Mainland Australia Pellet Heater Sizes
Most of the pellet heater size models above are only available in Tasmania, except the Piazzetta pellet heater range sold by Tas Energy and Heating. If you live in other states then please check out my post on where to buy a pellet heater in Australia. I also have some posts on the best pellet heaters in Australia and other pellet heater reviews you should check out. However, the short version is most retailers in Australia and outside of Tasmania sell Piazzetta pellet heaters. There are a few other brands but they are European, so cost about the same.
Why Pick a Big Sized Pellet Heater
Hopefully you can see from above that most of the time even a 9kw or medium sized pellet heater would be big enough. They can heat around 100m2 which is more than enough for most rooms and unless you live in a totally open plan house, then they would be enough to warm most houses. If this is the case then why go for a 13kw pellet heater? Or, if the room you want to heat is very small, say only 30m2, why go for a medium sized pellet heater when a small model would do?
First, if you want to warm the rest of the house then I’d go the medium or big models, as I mentioned above. However, the other benefit of going with a larger sized pellet heater is they come with more features. Small pellet heaters typically come with 8kg to 15kw hoppers for wood pellets. That’s fine if you are only heating one area, but some people (like myself) enjoy having 20kg to 30kg hoppers, so we don’t have to refill them offer. It’s just more convenient and less to worry about.
Next, and probably the most important if you are wanting to warm other rooms in your house, is a higher heat output will bring the room the pellet heater is in and the rest of your house up to temperature faster. This is obvious if you have a pellet heater in a shed or very large open plan area. You might only need an 8kw pellet heater but a 13kw pellet heater will heat the area much quicker. Again, it’s convenience and I like knowing my pellet heater has the additional heat if I need it.
The Nitty Gritty of Sizing a Pellet Heater
The 100 watts of heat per sqm is a very basic rule. If you want to really calculate what sized pellet heater you need then you need to measure the height of the room your pellet heater is in, what R rating insulation is in the ceiling, the walls and what type of windows you have, single or double glazed etc. Using this you’ll get a more precise calculation of what sized heater you should buy. I’ve included some links below to websites which will provide more detail.
Summary of Sizing a Pellet Heater
Picking a pellet heater that is too small will burn through more pellets as it struggles to heat the area but picking one that is too large might mean you spend a few thousand extra buying the pellet heater and won’t ever use that extra heat. If it was me I prefer to buy a bigger heater than I need. I think most people would be find with medium to big pellet heater models but if you are only looking to heat small to medium sized room and don’t care about the rest of your house and the size of the hopper, then a small sized pellet heater should be fine.
FAQ
How do I determine the size of my room for a pellet heater?
You can calculate the size of the room by measuring the length of the two longest walls and multiplying them together. For example, if the longest walls in your room are 6 metres and 5 metres, then your room is about 30m2.
What is the rough rule for heater size calculation?
A basic rule of thumb is for every m2 of space you need 100 watts of heat from any type of heater. For instance, if your room was 30m2, then you’d need a 3 kilowatt maximum heat output heater.
How do I size a pellet heater to heat a whole house?
The sizing depends on the layout or design of your house. For an open plan house, you could use the two longest walls of your house and use that. If your house is not open plan, it might be more complicated as heat can get trapped in hallways and rooms.
What options are there for heating a large house with a pellet heater?
For a large house or for an evenly distributed heat throughout the house, a hydronic pellet boiler might be a better choice. These burn pellets just like a pellet heater to heat water, which is then pumped around the house to heat rooms.
How do I know what heater model to consider?
Depending on the size of the room or your house, and how many kw pellet heater you need, there are different models to consider. This could range from small sized heat output models like the Matilda or Mini to large sized heat output models like the Grace 13kw pellet heater.
Why should I pick a larger sized pellet heater?
Larger sized pellet heaters may offer more features and more convenience, such as larger hoppers so you don’t have to refill them as often. They also provide a higher heat output, which can warm the room and the rest of the house up to temperature faster.
What factors do I need to consider for a more precise calculation of heater size?
Factors such as the height of the room, the R rating insulation in the ceiling, the walls, and the type of windows (single or double glazed) should be taken into consideration for a more accurate calculation of what sized heater you should buy.
What happens if I pick a pellet heater that is too small or too large for my house?
A pellet heater that is too small might burn through more pellets as it struggles to heat the area. Picking one that is too large might mean you spend more money buying the pellet heater and won’t ever use that extra heat. It’s recommended to choose a heater that fits your needs.
Are pellet heaters available outside Tasmania?
Yes, most retailers in Australia and outside of Tasmania sell pellet heaters. Check out local retailers or online stores for availability.
Resources
Heat Load Calculator website
Heating Load Calculator website
