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Installing a Gas Wall Furnace

A wall furnace packs all the elements of a forced-air heating system into a compact cabinet that mounts in or on an exterior wall. With direct-venting models, a pair of metal pipes—one inside the other—penetrates the wall. One pipe supplies fresh air for combustion; the other exhausts fumes. With direct venting, you don’t need to run a chimney to the roof. And because the fire is fed with outside air rather than house air, the system conserves indoor heat and runs more efficiently.

Check local community and building codes before buying a direct-vent furnace. Some codes restrict the type you can use and also may require professional installation. After installation, have the gas company come out to inspect it for safety; they will probably do so for free. Except for the gas line, there is nothing tricky about the installation. You’ll need to make a wall opening, and if you choose a horizontal model, you may have to install a header.

Position the furnace near the center of the wall, where doors, drapes, or furniture won’t block the airflow. The outside vent should be at least 24 inches below the eaves or other overhead projections and 12 inches above the ground. You’ll also need to run 120-volt power from a nearby wall outlet, a junction box, or the service panel. If you can cut the drywall or plaster accurately, the heater’s flange should neatly cover the hole and you won’t need to patch the wall.

Tools: Hammer, drill, saber saw or reciprocating saw, screwdriver, pliers, wire stripper, tubing cutter, pipe wrench, caulking gun.

Flush-mounted units. You can hang some units directly on the wall with brackets supplied by the manufacturer. This reduces carpentry and saves plenty of installation time, but the furnace will protrude out into the room.

Recessed units. Many units are recessed into the wall. Many can fit in the standard 14 1/2-inch space between studs; wider units call for extensive carpentry. To prepare for a recessed installation, locate studs, cut away drywall or lath and plaster, and remove any insulation.

Avoiding and Testing for Gas Leaks - Before working on a gas line, turn off the gas at the nearest shutoff valve. Open a window before opening the line, because a small amount of gas will be in the pipes. After making the connections, turn on the valve and test for leaks. Brush a mixture of dishwashing detergent and water onto all the fittings. Bubbles indicate a leak. All gas leaks call for immediate action. If you ever detect the unmistakable aroma of escaping gas, open some doors and windows, extinguish all cigarettes and open flames, close the main gas shutoff valve, and call your gas utility company.

1. Cut the opening. Remove drywall or plaster if you are installing a recessed unit. Determine where the flue will exit the house. Use a long bit to drill a hole through the drywall or plaster and out the exterior wall. Enlarge the hole using a saber saw (shown). When installing a flush unit, use an extra-long bit to drill the hole and cut from both the inside and the outside.

2. Run the lines. Drill holes and run three lines—code-approved gas pipe, cable for 120-volt electrical power, and low-voltage cable for the thermostat (Step 4). These can come through either the wall or the floor.

3. Install the vent. After you’ve installed the furnace, assemble the vent, making connections airtight by caulking the baffle plate. Be careful not to crack the connections where the vent pipes attach to the furnace and where the door opens for access to the burner and pilot. Leaks here will blow out the pilot.

4. Add a thermostat. Some units come with an integral thermostat, but a remote thermostat gives a more accurate reading and makes for more comfortable heating. Run the thermostat cable through the ceiling or the floor, or behind the baseboard.

Installing an Electric Heater

Electric heaters put out quiet, almost instantaneous heat— just what you need to take the nip from chilly bathroom air, warm a basement shop, or boost the temperature in a chronically cool room. Because electric heaters needn’t be vented, you can tuck one almost anywhere. Although these heaters use expensive electric power, using one strategically could cut the cost of running your central heating system. Consider, for instance, installing a baseboard unit in a room that’s used only occasionally.

Electric heaters require lots of power. With small 500- to 1,000-watt models, you may be able to tap into a 120-volt receptacle on a lightly used circuit. If a unit draws more than 1,000 watts, however, it should have its own 20-amp circuit. High-output heaters require a 240-volt current—a job for a professional electrician. An electrician also might install a remote switch next to a door or in another convenient location. Timer switches save energy by shutting off a unit after it has operated for a preset time period. For safety reasons, don’t place the heater or the switch near a bathtub or other wet place. And make sure the heater’s grille can’t be penetrated by a child’s fingers. The instructions here show how to recess a fan-powered model into a wall. A ceiling fixture with lamp-type heaters also may include an exhaust fan.

Tools: Drill, keyhole or saber saw, wire stripper, screwdriver.

1. Prepare installation site. Most wall heaters are made to fit between studs. Locate studs, drill a starter hole, then carefully cut out the opening with a keyhole saw or saber saw. In outside walls you’ll probably find insulation in the cavity. Cut it off above and below the opening.

2. Tap into an electrical source. Shut off power to any electrical circuit being worked on. For small units, tap electricity from a nearby outlet box. For larger units, you’ll have to run a new, separate circuit from the main service panel.

3. Run electrical cable through the heater housing. Most units come with a housing that has mounting flanges for attaching to plaster or drywall. Run the electrical cable through the housing before installing it.

4. Complete the electrical connections. Complete the wiring connections; the unit has a built-in junction box. Slip the heater into its housing and screw on the grille to make it tamper-resistant.

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