If you are trying to determine what size electric heater to install in your room for greatest electric heater efficiency there are some simple guidelines to follow in figuring this out. First of all, you need to figure out how big your room is, and then based on the square feet size of your room you should be able to determine what wattage heater to buy, as well as other HVAC load calculations.
There are, however, a few different things to take into consideration that may affect the outcome of your electric heater calculations and your heat gain calculation.
The first thing to figure out is how energy efficient the room is. For example, a modern building that is fully insulated will require about 10 watts of heat per square foot. If, however you have little insulation and your home was not built to be energy efficient, chances are that you may need to up that amount to 12 watts per square foot. For an older home that has no insulation, where the windows are quite drafty and not well placed you may need to count on 15 watts per square foot.
Another thing to take into consideration is the height of your rooms too. Regular ceiling height is around eight feet. If your ceiling is higher, however, for example in a conservatory or in an older styled home you need to increase the wattage of the heater by 25 percent for every two feet of height over the regular height of 8 feet.
Likewise in rooms with a lot of glass windows, again the conservatory comes to mind, or even a living room with big wall to wall windows, or sliding glass doors that lead to an outside patio, you also need to increase the wattage of the heater by 25 percent or more, depending on the amount of glass in your room.
If you find that your heating needs are over 2000 watts, it might be best and more efficient to buy two heaters, rather than just getting one big one. This will distribute the heat more evenly around the room, thus saving you money in the long run because the heaters will be better regulated and will operate at a lower temperature. Just using one heater to heat up a big room may not be that effective. You may find the end of the room away from the heater will be quite cool still and the heater will be forced to run all the time as the thermostat will never turn off.
Some examples:
- Heating a 12 x 10 foot room, in a modern day, energy efficient room: You would need to get a heater that is at least 1200 watts.
- Heating a 12 x 10 foot room, with 10 feet high ceilings: You would need 1200 + 25% or a 1500 watt heater.
- Heating a 12 x 10 foot room in an older house that is not insulated: You would need 1800 watt heater.
- Heating a 22 x 15 foot room in a house that has large glass windows all along one side: The room is 330 square feet so you would need a heater that is 3300 plus an additional 25% because of the glass windows, giving a total of 4,125 watts. In this instance you would probably want to invest in two heaters, installing them at opposite ends of the room.
There are many online sites that will provide you with an electric heater calculator that will quickly and easily provide you with a way to determine your heating needs. You will need to know the size of your room and be able to answer simple questions relating to ceiling height, insulation and other basic structural formations. You will also need some idea of the optimum temperature you would like to sustain while the heater is on. Some may find it easier to use these sites, than to try to figure out all of the details. You will
When buying your heater, it is likely that you often won’t be able to find one that is the exact wattage you need. If that is the case, you should just buy the next size up. Of course ,you should also consult with a local electrician before installing your electric wall heater as they often need to be on their own breaker. In some areas, you also need to have a registered electrician install them, so be sure to find out if that is the case in your area before going ahead with a self-installation.