Hydronic Baseboard Heater Sizing

  • 1-2 hours
  • Beginner
  • 0-20
What You'll Need
Tape Measure

A hydronic baseboard heater is a special type of heater which makes use of liquid such as water to control the temperature within a room. The heater itself is fitted at the bottom of a wall and they are designed to work by sucking in the cold air at the bottom, heating it up and then pushing it back out of the top of the heater. Because these heaters work at lower temperatures than most other types of heater they can be installed so that they are flush with the wall.

Hydronic baseboard heaters are different to other types of heaters and so you will need to give some special consideration to when you are installing them. Ensure that you are choosing the right size of heater to provide plenty of heat to your room. Choosing a heater which is too small will result in the room being unable to heat properly, and a heater which is too large will be a waste of energy.

Step 1 - Measuring your Room

First start by using your tape measure to measure the length and width of your room. This doesn't need to be extremely accurate as it will only be used to calculate the heating requirements for your room.

Step 2 - Work out the Square Footage

Calculate the square footage by multiplying the length (in feet) by the width (in feet) of your room. This will give you an answer in square feet, if you measured in meters then you will get an answer in square meters.

Step 3 - Insulation

Insulation is what prevents heat from escaping in your home, the better the insulation your home has the less heat you will need. If you have a very old house then the insulation will probably be pretty poor. In this case you should allow 12.5W per square foot. In an average house with R-11 insulation in the walls and R-19 insulation in the ceiling you will need 10W per square foot. In a very modern house with full insulation, R-19 in walls and R-38 in ceiling you will only need to allow 7.5W per square foot.

Step 4 - Any Adjustments

The watts required per square meter are for an average room, if your room is a bathroom then you need to use a minimum of a 1000W heater. If your ceiling is over 8 feet then the wattage needs to be increased by 1/4 for every 2 feet over this height.

If you live in a part of the country which has very harsh winters then you should fit a more powerful heater to account for these harsh winters. The figures above are simply a rule of thumb.

Step 5 - Choosing Heater

Next you just need to choose your heater. They are all measured in watts and so it's a simple matter of finding one which will be able to heat a space the size of your chosen room efficiently and effectively.