If you’re on your journey of buying a wood burning stove, then one of the first questions you’ll want to get the answer to is: what size of wood burning stove should I get? This was the exact same question I found myself asking on our search for a brand new log burner. So, in an effort to be helpful, I’ve put together a simple calculator to help everyone else who find themselves in the same position as me!
The size calculator is below, but before you do it it’s important to understand that wood burning stoves have two types of “sizes.”
The first is obviously their measurements (length, depth, width). All you have to think about with this is whether these measurements will work in your home – simple.
The second is their kilowatt output. This is the measurement that stove manufacturers provide that allow you to compare how much heat a stove produces regardless of its standard measurements. A good way of visualising Kw output is to think of a plug-in fan heater – generally, they give off a 2 Kw hour heat output.
The calculator below is all about working out the kilowatt output you need for your wood burning stove.
Once you have figured that out, then all you need to do is go shopping!
All that being said, you will find that the standard LxDxH measurements of your wood burning stove directly relate to the KW output. I mean, think about it: if you can burn more wood in there, you’ll end up with more heat!
What size wood burning stove do I need? Easy Calculator
Ok so, this shows you the minimum size of stove you need in a rough figure. Obviously, you’ll need someone to actually give you advice based on the specifics of your home before you buy your wood burning stove.
You may have been surprised that the number given is so low. Don’t worry – this doesn’t mean that the calculator is wrong, it just means that this is the minimum size you require. The question you’re probably asking yourself right now is: so how come all of the stoves I’ve seen have so much more Kw hours than this calculator?
Well, the answer is actually pretty simple: just because a stove is, say, a 5 kw hour stove, doesn’t mean it always runs at 5kw hours. Think about it: it needs time to heat up , and it requires constantly full “tank” of wood to run consistantly at 5kw hours.
So, even though you may have a low figure given, it doesn’t mean you have to go for a stove that exactly matches this output.
So what size wood burner should I get for a typical UK house?
While obviously there’s no one size fits all, I’ll give you a rule of thumb answer to help you in your search (this one took me ages to figure out). I’ve based this on the common sizes made available on wood burning stove maker websites.
- 3 – 5 kw hour stoves – likely to be good for a standard sized living room in a medium to well insulated house
- 5 – 8 kw hour stoves – likely to be good for a larger kitchen/diner, or a really poorly insulated standard-sized living room
- 8 – 10 kw hour stoves – likely to be most suitable for a big, open plan room with high ceilings
- 10+ kw hour stoves – at this size, you’re talking a stove that will chuck out some serious heat. Likely not to be suitable for a “typical” UK house.
How big is too big for a log burner?
Some wood burning stoves can go up to a 30 KW heat output (or even more!) so at some point there is absolutely a limit to how big you can go when it comes to choosing a wood burner. If you buy a woodburner that has a much higher Kw output than you need then you’ll run into a few problems:
- First, when your burner is up to temperature, you’ll find that the room its in will just get too hot to sit in it comfortably. Think windows open, sweaty backs, and generally feeling “hot and bothered”
- Second, as a general rule of thumb the bigger the wood burner, the bigger the KW output. If you go for a beast of a fire with a higher than needed KW output then it’s going to look oversized and a bit silly. A bit like when you walk into a tiny living room and there’s a 90” TV taking up a whole wall.
That said, you obviously don’t have to run your wood burner at “full burn”.
So, in theory, you could get a bigger KW output stove than needed, but then just burn fewer logs.
This is worth bearing in mind if you find the *perfect* stove, but it’s two or three kw hours more than you need.
In my opinion though, you don’t need to worry too much about not getting enough heat. Much better to get one that is “reasonable” in it’s Kw hours. You’ll be able to use it more often and in milder autumn weather without having to worry that it’s going to run too hot and make a whole room unlivable.
Do you need an air vent or air brick for a wood burner?
In the UK, if your house is well insulated and isn’t very drafty, then you’ll need appropriate ventilation if you’re having a wood burning stove installed, according to building regulations (see here on the HETAS site). Having more ventilation helps your fire to burn better, and stops smoke from coming back into your house.
Now, there doesn’t seem to be a black and white rule about when you should have an air brick or air vent installed. It comes down to each home’s unique situation, and the size of the stove you want to have. Bottom line is that your installer will be the one to properly advise you.
But, if it helps, the rules of thumb that we were told by our wood burning stove installer was that if your stove is more than 5kw, in an average sized living room, in a well insulated house then you’ll most likely need an air brick installed. Now, we don’t live in a new-build house, and there’s plenty of drafts coming in (oh, it’s so fun!) so we didn’t need one put in for us.
I think if we were to live in a sealed-up new build, then it’s probably likely that we would have had to have an air brick put in whatever the situation.
Don’t worry about having one installed if that sounds like it applies to you. The regulations specifically set out that air vents shouldn’t be installed where they are likely to cause an uncomfortable draft etc.
How this wood burning stove size calculator works
This wood burning stove size calculator works by working out the amount of air volume in your room (LxWxH) and then applying an adjustment based on your insulation level.
This “adjustment factor” might sound complicated, but it’s actually pretty simple. Basically, the better insulated your home, the less the heat loss is.
So, if you have more insulation, you’ll need less KW hours from your stove to keep the temperature in your house comfortable.
So, the calculator basically divides the volume in your room by a standard heat loss amount for different types of insulation levels and gives you an indication of the approximate amount of KW hours you then need. In geeky terms, this is all about the “U” value of your insulation – the higher the value, the more insulation you get!
The following is a rather dry video, but it helps you to get your head around insulation and its effect on heatloss as expressed in Kw hours. Probably worth a watch if you’re struggling to sleep!
