Combustion Air Fan Gas Furnace

In high efficiency furnaces the combustion air is generally piped in directly from the outside straight into the combustion chamber.

Combustion air fan gas furnace.

Sizing combustion air openings step 1. These small air combustion fans or blowers are in addition to the large indoor blower on the furnace. Where all air is to be taken from the outdoors divide the total input of all gas appliances in the space by 4000. One cfm of air for each 2 400 btu hr.

Proceed to either part a part b or part c. Gas furnace inducer or combustion blower problems when troubleshooting understand you are working with potentially lethal voltages and a highly flammable gas. On the other hand if you were using the inside volume of air in the house for combustion it would be pulling it into the furnace and sending it right outside. It may also be used with millivolt water heaters and more than one appliance.

If a gas fired furnace is located in an open area basement or utility room and the ventilation is relatively unrestricted there should be a sufficient supply of air for combustion and draft hood dilution. The furnace is now a closed loop system pulling air from the outside and then sending it back out with the combustion gases. To properly size the combustion air openings add the input of all fuel burning equipment inside the boiler room. Enter the input ratings of all appliances in table 1.

The easy answer is oxygen is a key element in combustion therefore your furnace needs air. Some heating appliances furnaces boilers and water heaters are designed to isolate the combustion process from the living space entirely avoiding the need for complex combustion air and venting schemes. This is roughly the equivalent of running a bathroom exhaust fan into your furnace s combustion chamber. If you do not have the ability to do these operations safely do not attempt them.

Total the column. Of area for each 1 000 btu hr. Input of gas burning appliances in the room. All gas fired appliances must have both a flue chimney to exhaust the leftover products of combustion outlet as well as combustion air to provide the oxygen for burning inlet.

This creates a dedicated source of oxygen and also a cleaner install as no other provisions need to be make for combustion air.