Furnace Installation Made Easy

Locate the gas supply and electrical power lines, a vent for the furnace and connections to heat supply and air return ducts in the house. Set the unit in place, with its supply and return plenums or openings facing the appropriate ducts, and gas and power lines accessible for connections. Make sure all gas and power is off. Level the unit with a level, typically using adjusting screws on the bottom of the furnace to raise or lower the unit, turned with pliers or a screwdriver.

Connect the supply ducts to the output or supply plenum, using adjustable straps; typically flexible ducts slide over metal sleeves on the plenum. Install the return ducts to the return plenum, which usually is adjacent to the supply side. Seal the seams of both ducts with heat-resistant tape; make sure there is straight flow for both ducts, with no crimps or bends.

Attach air inlet and vent pipes on the unit, typically PVC types, to an outside vent, through a wall or ceiling. Slope vent pipes slightly to prevent any buildup of moisture condensation. Vent furnaces on exterior installations so the air flow is directed away from the house to an open area where it can cause no harm.

Install the gas connection, using a tee connector with a capped nipple pointing down; this is to allow drainage in case of any moisture buildup. Attach the gas supply, with the gas line on the top of the connector and the link to the furnace on the side. Fasten the tee typically with screw-type compression fittings. Use pliers or a wrench to tighten the connectors. Turn the gas on and test for leaks with a commercial leak detecting spray; look for bubbles to indicate leaks.

Make a low-voltage electrical connection to tie the furnace control panel to the thermostat in the house, typically with a 5-wire system; you may have to run these wires through walls if the thermostat is some distance from the furnace. Match the wires to the respective terminals, W to W, R to R, usually color-coded such as W for white wire. Refer to specific user manuals for schematics onthe furnace and the thermostat.

Run the 110-volt power line from a fuse box near the furnace to the power supply for the blower motor; all furnaces must have an adjacent disconnect, typically a fuse box with a fuse which can be removed to cut power. Connect the three wires, black "hot" to black, white "neutral" to white and bare copper to green ground. Fasten these with wire nuts or with straps or screws on the unit.

Connect a PVC drain pipe to the furnace condensate drain, at the bottom of one side of the furnace. Run the drain away from the house to a flower bed or area which will not be hurt by some moisture. Drain to a floor drain if the furnace is installed in a house.

Turn on gas and electrical supplies and run the furnace through a heat cycle, testing again for gas leaks, proper condensate drainage and electrical connections. Check duct connections for any leaks. Stop the test immediately if there are any leaks or unusual actions. Make sure the thermostat will adjust the furnace output.