# Calculators

Using the above tables you can get an approximate idea of the heat output needed for an average room. However these tables are for guidance only. Here are some suggestions for getting a more accurate idea of your requirements:

## Factors that affect your decision:

1. What you want to heat? If you wish to heat a room then you are looking for a stove, if you wish to heat a room and also water or radiators, then a boiler stove, could be your solution. If you wish to heat all of your home and domestic hot water, then a boiler is the choice for you.
2. What fuels you may wish to use? If you have access to chopped wood, then a wood burning stove may be an option for you. You may wish to use renewable fuels such as wood pellet, in which case either a pellet stove or a pellet boiler may be an option for you.
3. Where do you intend to put it? If you wish to put it in a room such as the kitchen or living room then a stove or boiler stove is your solution. If this is the case then you also have to consider the following:
• Location in the room – is it on an outside wall for a flue or is there a chimney in the room?
• Base for under the stove – this must meet certain requirements set down in the building regulations.
• If it is a boiler, then pipes will have to be plumbed to the location of the stove/boiler.
• As pellet stoves and boilers are electrical, a power source will be required near the appliance.

# How to work out what size stove you need:

## Why is this important?

It is very important that the output of the stove matches the area that you are trying to heat. There is no point having a stove with a very large output in small room, as the stove will not run efficiently and be too warm. Equally there is no point in having a stove with a small output sitting in a large room, which would not heat the room sufficiently. It is essential that you know the size of the room you are trying to heat at least. Other factors come into play as well, but a general estimate of the output needed to heat the room can be made using the measurements from the size of the room. There are two ways of doing the calculation,

• one is in feet, which calculates the minimum amount of British Thermal Units (BTU’s) needed to heat the room (this can be converted into kilowatts)
• the other is in meters, which calculates the minimum amount of kilowatts (kW) needed to heat the room.

Remember, that these calculations are a guideline. We recommend that you always take independent professional advice prior to making the final decision.

## Calculation in feet:

Step 1: You need to take three measurements – the length and the width of the room, and the height of the ceiling. (L, W, H) Step 2: Multiply each of these measurements – the length by the width and then by the height, and now you have the volume (cubic capacity) of the room). (L x W x H) Step 3: You multiply the volume by a factor of either 5 , 6 or 7 based on the following:

•      If your room has an average amount of windows and doors and has an average amount of insulation, then multiply the volume by a factor of 5. (L x W x H) x 5
•     If your room has a higher than average amount of windows and doors and has a lower than average amount of insulation, then multiply the volume by a factor of 6. (L x W x H) x 6
•     If you room is north facing, or has little or no insulation, or has a very high number of windows and doors, then multiply the volume by a factor of 7. (L x W x H) x 7

You now have the number of BTU’s (British Thermal Unit’s) required to heat your room. Step 4: You can convert this total to kW’s by dividing it by 3411.80. Example:

• Room dimensions – Length 17 feet, width 15 feet and ceiling height 8 feet
• 17 x 15 x 8 = 2,040 cubic feet
• for average insulation and number of windows, 2,040 x 5 = 10,200 BTU’s
• to convert to kW, 10,200 / 3411.80 =  2.99 or 3 kW stove

## Calculation in metres:

Step 1. You need to take three measurements – the length and the width of the room, and the height of the ceiling. (L, W, H) Step 2. Multiply each of these measurements (L x W x H), and now you have the volume (cubic metres) of the room). (L x W x H) Step 3. As a guide 1kW heating output will heat either 10, 14 or 25 cubic metres of space depending on windows and insulation. So you divide the volume by a factor of either 10 , 14 or 24 based on the following:

• If your room has an average amount of windows and doors and has an average amount of insulation, then divide the volume by a factor of 14. (L x W x H) / 14
• If your room has a higher than average amount of windows and doors and has a lower than average amount of insulation, then divide the volume by a factor of 10. (L x W x H) / 10
• If you room is north facing, or has little or no insulation, or has a very high number of windows and doors, then divide the volume by a factor of 25. (L x W x H) / 25

You now have the minimum amount of kW’s required to heat your room. Example:

• Room dimensions – Length 5 metres, width 4 metres and ceiling height 2.3 metres
• 5 x 4 x 2.3 = 46 cubic metres
• for average insulation and number of windows, 46 / 14 = 3.28 kW stove