Everything You Need to Know About a Wall Furnace

After Alice Parker received the first central air heating system patent in 1919, it didn’t take long for other home heating innovations to appear.

The first coal-fired wall furnace, designed to minimize cost and necessary floor space, appeared around 1935. Recessed into the wall, the device pushed warm air through ducts to different parts of the home via a small motorized fan. Wall furnaces grew more popular by the 1950s because they provided a space-saving alternative to cast iron radiators, full-sized standard furnaces and electric baseboard heaters.

What Is a Wall Furnace?

Also called wall heaters, wall furnaces are self-contained, compact heating units permanently mounted in or on the wall of a building and vented directly through the wall or roof.

Often producing warmth by burning fuel, but occasionally powered by electricity, these units circulate air inside a sealed internal chamber. The air is warmed through combustion or an electric heating element, then blown out the front of the heater and into the room being heated.

Unlike standard forced-air furnaces, modern wall furnaces don’t use any duct work for distributing warm air or venting combustion gases. Their small size and relatively simple installation makes them ideal for heating small, open spaces. Wall furnaces can generate heat from one of three sources:

• An internal electric element;
• The home’s natural gas line;
• A liquid propane gas tank stored on the property.

Wall Furnace Costs and Considerations

If the space you want to heat is small and fairly open, a wall furnace is well worth considering. Typically, wall furnaces cost between $1,800 and $2,500, depending on size, heat source and heating capacity. Wall furnaces average half the unit price of a central forced-air furnace. Installation costs are also lower because wall units don’t require ducts and venting required is comparatively simple.

But wall furnaces certainly aren’t for everyone. They average only half the heat output of central forced-air furnaces in BTUs, depending on the size of each. And since they’re direct heaters — they rely on natural air movement in a building to heat the space — they become less effective the further away they are from an area that needs heat.

They work great for well-insulated smaller spaces with few walls. But larger homes, colder winters and less-than-ideal insulation will all likely lead to unsatisfactory performance from a wall furnace.

Wall Furnace Safety Measures

Modern, properly-installed wall furnaces are remarkably safe. However, like all heat sources, they come with risks. Knowing these potential problems and how to deal with them will prepare you for the safest possible experience with a wall furnace.

• Always hire a licensed furnace specialist to install a gas-burning wall furnace. Gas units involve more risk than electric, because there is the possibility of gas leaks and carbon monoxide poisoning. Many areas also have strict rules regarding how venting is installed, what sort of pipes are used, how the gas line connects, etc.
• Although electric units are safer, unless you’re an experienced electrician, it’s still best to have an electric wall furnace installed by a licensed professional.
• Have a furnace technician do annual inspections of your unit to make sure it’s functioning properly.
• Keep the heating coils of your electric wall furnace clean and dust-free, because dust and debris on the coils can be a fire hazard.

Wall Furnace Energy Efficiency Ratings

For the one room or mainly open concept space a wall furnace is designed to heat, its energy efficiency is quite good. Because wall furnaces blow warm air directly into the room instead of forcing it through a network of ducts, wall furnaces are more energy efficient than their central air counterparts.

Today’s wall furnaces are often rated at 80 to 90 percent annual fuel utilization efficiency (AFUE). Note that older units that work with a natural draft instead of a fan are often considerably less efficient.

Wall Furnace Maintenance

Like all heating appliances, wall furnaces need routine maintenance.

Start by cleaning the outside of your furnace with a damp cloth, paying special attention to the vents, making sure they’re clear of dust and dirt. Next, shut off power to your furnace, then remove the outer cover to access the inside. Use a duster or a carefully handled vacuum cleaner with a soft brush attachment to remove dust and debris from the fan blades and motor.

Once a year, if you have a gas burning unit, clean your venting (the exhaust pipe that leads outside). Make sure to wear a dust mask and rubber gloves for this job. If you’re unsure of yourself, hire a licensed technician for the cleaning. Otherwise, carefully open the vent pipe and remove any debris with a damp rag or vacuum cleaner.

Wall Furnace Fixes and Repairs

Most modern wall furnaces include lots of specialized parts and computerized functions, timers and programs. That’s why if something goes wrong, you’ll almost certainly need to call in a licensed specialist to fix it. Some common problems you might encounter are:

• Banging noises;
• Pilot light problems;
• Short cycling;
• Gas leaks;
• Thermostat problems;
• Limit switch problems.