The National Weather Service is predicting the possibility of a massive weekend snowstorm in Boston. High-efficiency furnace owners should take note! Heavy snowfalls can interfere with the proper operation of high-efficiency furnaces, but a few simple precautions can help keep your furnace working properly, even in bad weather.

Like conventional furnaces, high efficiency furnaces exhaust waste gases directly to the outside of the home. Unlike conventional furnaces, high efficiency furnaces also take in fresh air from outside the home. The free movement of fresh air and furnace exhaust gases is critical to the safe, proper operation of a high-efficiency unit.

The high efficiency intake and exhaust ports may be separate pipes or they may be a combined unit called a concentric vent terminator. This vent design provides isolated fresh air and exhaust capabilities in a single unit. The concentric vent terminator can be used in either a horizontal (through the wall) or vertical (through the roof) configuration. Homeowners and installers alike often prefer the concentric vent terminator because this approach requires only a single hole to be made in a home’s exterior wall, or through the home’s roof.

For those homeowners whose high-efficiency units exit through separate pipes through the side of the home, significant snowfall can interfere with the free flow of air through the intake and exhaust ports. This can, in turn, cause snow and ice to accumulate in and around the ports, and reduce or completely block air flow to the furnace. The ultimate result is that the unit will shut down, probably just when you need it most!

As a general rule, keep a 3′ area around your high-efficiency intake and exhaust ports clear of snow, organic debris (including decorative landscaping), and other objects. Do not stack or store items around the intake and exhaust ports for your high efficiency furnace and remove snow buildup periodically during a storm to prevent icing.

Your intake port should have been installed above the “snow line” – at least 1′ above grade. If your intake port is not at least one foot above the ground, clear the area regularly throughout a storm to ensure that snow buildup and icing don’t affect the operation of the furnace. When your resources permit, consider having the intake port raised to at least 1′ above grade to prevent future problems.

Keeping your exhaust port clear is also very important. The exhaust port allows toxic by-products of combustion to exit the home safely. As with the intake port, maintain a clear 3′ perimeter around the exhaust port. Don’t stack or store items in this space and clear away snow accumulation regularly to allow the exhaust gases to escape your home safely.

A distance of up to 3′ should separate your intake and exhaust ports. If your intake and exhaust ports are right next to each other, your intake port could be admitting contaminated exhaust air back into your home. The concentric vent terminator is an exception to this, but this vent is designed specifically to keep fresh and exhaust air separate. If your intake and exhaust vents are right next to each other, consider having one of the ports moved, or consider having a concentric vent terminator installed to prevent possible exhaust gas contamination of your furnace’s intake air.

As a side note to heat pump owners – your heat pump condenser can also leave you out in the cold if you don’t take proper precautions during a storm. Some heat pump condensers have a special defrost mode that you can engage to ensure that your condenser remains frost-free. Some defrosters are automatic, while others work on a timer that you can adjust.

If you have a timed, adjustable defroster on your heat pump condenser, set the defrost timer to turn on every 30 minutes during the storm to reduce frost buildup. (Some frosting is normal, but a heavy layer of frost isn’t!)

To keep your heat pump happy, make sure the condenser area is clear of debris and objects that will restrict air flow to the condenser unit before the snow starts to fall. As with a high-efficiency furnace, keep a clear, 3′ perimeter around the outdoor unit.

Clear away snow buildup on the unit regularly to prevent melting snow from turning to ice. Do not cover, block or obstruct the unit while snow is falling, however.

With this particular storm system, the National Weather Service is predicting between 1′-2′ of snow on Friday and Saturday, and is predicting freezing rain or sleet on Monday. Freezing rain is a known hazard to heat pump condensers. If ice buildup is preventing the unit’s fan from operating properly, shut the unit down and clear the ice manually, or let it melt on its own.

Do not attempt to break or chip the ice that has accumulated on the unit; this could cause expensive damage to the copper piping. Instead, use warm water to melt away the ice buildup. (Make sure the water you’re using is draining away from the unit!) If the water you’re using to de-ice your condenser doesn’t drain away from the unit properly, clear the gutters on the unit or move the water away manually before it freezes.

If you cannot unfreeze your heat pump condenser, give us a call at Boston Standard Plumbing & Heating at (617) 362-0377 . We offer true, 24-hour emergency service, and we’ll restore the heat to your home.

Visit Boston Standard Plumbing on Facebook!

DIY Blog, DIY Heating, Tips and Tricks

Skip to content