Choosing the size of your heater for a particular space can be a challenging task. It’s like buying outfits online - a bit hit and miss. You can calculate the requirements on the basis of the manufacturer’s sizing charts, but there’s no surety that the quality and size will be just fine and you won’t know that until you purchase that item and try it out. Luckily, with heating there are many methods to reduce the chance and understanding a few measurable variables will help you make a smart and civilized choice. Like apparels, heaters should be the proper size, but they’re more like shoes and socks, a close fitting is always good. The ideal way is to understand your goals and needs, then talk to a manufacturer or heating supplier for particular recommendations.

How do the experts handle it?

When sizing the heater for a whole house, compound “load calculations” are performed that include the construction type, windows and doors, the entire house’s layout, the local climate data, and the insulation levels. To find out what size you need to buy a heater for a specific space or a room, you’ll notice some similar factors but at an extremely simple level. The purpose here is to analyze the requirements and choose an excellent fit for your home.

Basic sizing and heat values

Electric heaters are usually rated and sized by wattage. Heaters that use gas (including kerosene, natural gas, and propane types) are valued by the BTU (British thermal unit). Obviously, when you’re deciding what heater size you need, judging in terms of the weight of water is similar to baking a dessert with a plumb bob. So, let’s be clear. As per the basic guideline, you require 10 watts of electric heater for every square foot of an area. Thus, a 300-square foot space requires an electric heater with a power of 3000-watt. You can convert watts into BTUs easily by multiplying 3000 by 3.41.

For your understanding: a BTU is a form of heat energy needed to increase the temperature of 1 pound of water.

Measure the room or area

To install a heater in your room or a specific area, begin with some main load calculations and implementing guidelines. The initial step is to measure the space or room by multiplying the width by the length. Heater manufacturers do this calculation on the basis of room area only and it’s more precise to take measurements in cubic feet. Just multiply the space by the height of the ceiling.

Other factors

The calculations explained above provide you with a beginning point for knowing what size heater you should install. There are some other factors that will provide a more precise estimate. An educated installer or sales rep can use this knowledge in making suggestions for size and some manufacturers offer sizing charts that demand more than the height, space, and width details.

Some more factors that you should consider are;

  • Room insulation levels
  • Type and number of doors and windows in the space (and how frequently they are opened)
  • Height of ceiling

In simple terms, while deciding to buy a heater, remember that a room with more doors and windows means you need a powerful heater. The same is required if the room is not insulated, or is poorly installed. Even the windows from the best company have very low insulation quality, so discuss the windows and size of your room with your heater manufacturer/ supplier.