Combustion Air Fan Gas Furnace

One cfm of air for each 2 400 btu hr.

Combustion air fan gas furnace.

To properly size the combustion air openings add the input of all fuel burning equipment inside the boiler room. Input of gas burning appliances in the room. Field controls cas 6 fan in a drum combustion air system up to 900 000 btu this product is designed for use with any oil or gas fi red furnace water heater or boiler with 24 vac or 120 vac control systems. Enter the input ratings of all appliances in table 1.

Of area for each 1 000 btu hr. 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. 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. Where all air is to be taken from the outdoors divide the total input of all gas appliances in the space by 4000.

In high efficiency furnaces the combustion air is generally piped in directly from the outside straight into the combustion chamber. 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. Total the column. It may also be used with millivolt water heaters and more than one appliance.

Proceed to either part a part b or part c. This is roughly the equivalent of running a bathroom exhaust fan into your furnace s combustion chamber. Direct vented combustion appliances are designed and tested to burn fuel and draw combustion air properly even when high winds hinder draft. The easy answer is oxygen is a key element in combustion therefore your furnace needs air.

These small air combustion fans or blowers are in addition to the large indoor blower on the furnace. This creates a dedicated source of oxygen and also a cleaner install as no other provisions need to be make for combustion air. If you do not have the ability to do these operations safely do not attempt them. 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.

The furnace is now a closed loop system pulling air from the outside and then sending it back out with the combustion gases.