How to select a vent-free gas heating product

  • Step 1: Determine if your house construction is loose, average or tight.

  • Houses with loose construction typically have no storm doors or storm window, no vapor barrier, no weather stripping and if fireplaces are present they are undampered. Houses with average construction typically have loose fitting storm doors and storm windows, a vapor barrier, weather stripping and if fireplaces are present they are dampered.
  • Houses with tight construction typically have tight fitting storm doors and storm windows, a vapor barrier, weather stripping and if fireplaces are present they are dampered.
  • Step 2: Determine if you will install the vent-free gas heating product in an isolated space or a freely-communicating space.

  • An isolated space is a room that does not have openings into other rooms and has one or more doors to other rooms that can be closed.
  • A freely-communicating space connects to other rooms in the house through openings not equipped with doors - for example, archways, doorways without doors, hallways and stairways.
  • Step 3: Determine the size of your space for which supplemental heating is desired.

  • In feet, measure the length of the space, the width of the space and the height of the space from floor to ceiling Round each measurement to the nearest foot. Multiply these three numbers (length x width x height). This will tell you the size of the space in cubic feet (ft 3). The space may be a single room or adjoining rooms and other areas such as hallways and stairwells. Exception: If the space is a single room that can be isolated from the rest of the house by closing the door(s), then calculate onlye the space of that single room.
  • Step 4: Determine if you want a vent-free gas heating product that cycles on and off by means of a thermostat control or one that you must turn on and off with a manual control.

  • Step 5 : Determine the vent-free gas heating product's input by referencing the charts below.

  • If you will install the vent-free gas heating product in a freely-communicating space, use Chart A. Find the column that matches your house construction (loose, average, or tight) and the type of control you selected (thermostat or manual control). In that column, find the number that is closest to the size of the space you calculated. In the far right-hend column of the chart will be the input of the product you need. You should purchase a vent-free gas heating product of approximately this input.
  • If you will install the vent-free gas heating product in an isolated space, use Chart B. Find the column that matches your house construction (loose, average, or tight) and the type of control you selected (thermostat or manual control). In that column, find the number that is closest to the size of the space you calculated. In the far right-hand column of the chart will be the input of the product you need. You should purchase a vent-free gas heating product of this input or less.