Combustion Air Fan Gas Furnace

A gas furnaceneeds approximately thirty feet of air for every foot of gas used.

Combustion air fan gas furnace.

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. 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. 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. To properly size the combustion air openings add the input of all fuel burning equipment inside the boiler room.

Proceed to either part a part b or part c. In high efficiency furnaces the combustion air is generally piped in directly from the outside straight into the combustion chamber. These small air combustion fans or blowers are in addition to the large indoor blower on the furnace. It may also be used with millivolt water heaters and more than one appliance.

This is roughly the equivalent of running a bathroom exhaust fan into your furnace s combustion chamber. One cfm of air for each 2 400 btu hr. Direct vented combustion appliances are designed and tested to burn fuel and draw combustion air properly even when high winds hinder draft. This creates a dedicated source of oxygen and also a cleaner install as no other provisions need to be make for combustion air.

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. If you do not have the ability to do these operations safely do not attempt them. Enter the input ratings of all appliances in table 1. Where all air is to be taken from the outdoors divide the total input of all gas appliances in the space by 4000.

Of area for each 1 000 btu hr. Total the column. Gas furnace inducer or combustion blower problems when troubleshooting understand you are working with potentially lethal voltages and a highly flammable gas. Input of gas burning appliances in the room.

Sizing combustion air openings step 1.