Gas Furnace Flue Pipe Sizing

Consequences of improperly assembled vent pipes problematic chimney flue deteriorating chimney walls can be sometimes fatal fire and carbon.

Gas furnace flue pipe sizing. Higher btuh furnaces produce higher flue gas temperatures. The design btuh british thermal units per hour capacity of the vent plus the furnace input and efficiency are factors affecting the temperature of the flue gases. I have a single 2650 sq ft home that was once subdivided one side had a 133 000 btu oil boiler and i have a 115 000 gas boiler. So let s calculate or why don t we skip those calculations and i ll give you the answers.

Proper furnace water heater venting is an extremely important issue which depends on the performance of the house chimney chimney flue or other exhaust assemblies. The different types of venting. Reduce furnace flue vent connector size below furnace outlet size. To make it simple if you have a gas water heater with a 3 draft hood and a furnace with a 4 flue collar connected to the same chimney flue you d calculate that chimney flue size based on the 3 draft hood the smaller of two.

The pipe then slips into the hole and is sealed with a high temperature silicone caulk. 6 flue 28 27 square inches 8 flue 50 27 square inches total 78 54 square inches. When we are talking about gas furnace vent pipe code we need to talk about the different types of the vents first after all you want to keep your family safe from harm. The conditions explained in this post also apply to the wood burning appliances.

Traditional gas fired forced air furnaces produce hot combustion exhaust gasses and therefore need metal vent pipes or chimneys. Oct 13 2012 brent said. You would core a hole 1 4 to 1 2 inch bigger than the outer diameter of the pipe. Clearance installations must provide the proper clearances to combustible materials as specified in the appropriate underwriters laboratories inc.

Illustrations of proper gas fired water heater venting using type b double wall vent pipe through a roof above or through a chimney below include details for the flue vent connector such as the requirement of a minimum vent connector upwards slope of 1 4 per foot of horizontal run. Let s say you have a job where you combine a furnace or boiler 8 flue with a water heater 6 flue. Conditions for listing as stated in the product catalogs and embossed on the vent pipe. Flue gas temperatures that do not exceed 400 degress fahrenheit above ambient for category i appliances.

To determine the main flue size refer to figure 3 and locate the square inch area of each individual flue size. Well making sure that you choose the right venting style will protect them. I want to purchase a new boiler to heat both sides which i have zoned.