Why Cold Temperatures Can Wreak Havoc on Your HVAC Unit

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Don’t let the next winter storm take you by surprise.

Heating, ventilation, and air conditioning (HVAC) units are built to withstand the snow and ice, but every unit has its limits. Many units in our area were pushed past those limits during Winter Storm Grayson last week. The storm rolled through January 3rd and 4th and left a half foot or more of snow piled up in eastern sections of North Carolina. Wind gusts topped 70 mph in some areas!

Even if you’re aware of the extreme importance of interior HVAC care, specifically the changing of the air filters, switching to programmable thermostats, and getting the system inspected annually by a professional, you should never lower your guard when it comes to your heater and air conditioner. The care of the outside HVAC unit is crucial, especially since snow and ice can have a lasting effect on your system well into the spring and summer.

Ice Build Up

Not all incidences of snow and ice build-up is an emergency situation. In fact, in a heat pump, it’s a normal part of operation on extremely frigid days. Heat pumps operate via a refrigerant that absorbs temperature from the Earth’s atmosphere. When the refrigerant absorbs heat, excess moisture builds up on the processing coils. When outside temperatures are at or near zero degrees, that moisture freezes up almost instantly. The system may run a little more sluggishly on those very brutally cold days, but it will return to normal as the temperatures rise.

Falling Snow and Ice

A “normal” ice buildup on heat pumps and HVAC systems is pretty rare because units are manufactured to take into account this moisture freezing with an automatic defrost setting. When ice buildup is detected, the unit switches to a heat distribution mode to melt ice off the coils—all while back-up heat keeps your house warm. Sometimes thermostats will display “auxiliary heat” or “aux heat” on the wall display in your home when this occurs.

It generally takes 30 minutes for the defroster to do its job, but it needs air flow to do so. When snow builds up around the outdoor unit and ice forms on top of the HVAC, components can’t breathe and the defrost cycle will not work—raising electricity usage, but, more importantly, putting unneeded strain on the entire system. And this is also true for units covered in such things as leaves, shrubs, and ivy—so, make sure you keep the area around units clear year-round so they can breathe and function properly. Keep in mind that when it is approximately 35 degrees outside, the unit can no longer efficiently transfer ‘heat’ from the outside air into your home, making it more difficult to keep your home warm.

Any Lasting Damage?

So, we know that snow and ice causes inefficient operation, but other problems with the unit can appear as well. When a unit is encased in ice, an emergency shut-off is triggered as the system freezes up. With no heat coming into your home, the water pipes are more likely to burst and cause major damage.

Even though the components of your outside unit are designed to withstand the elements—hot or cold—it may still be possible for heavy ice to bend the aluminum fan and coil fins. If this happens, you’ll most likely know because of the noise the unit will make! Another concern during weather extremes is the workload placed on unit components—they may be working twice as hard with limited airflow which can cause a burn out or short circuit.

Planning Ahead

Protecting your HVAC system from extreme weather starts at installation and should continue throughout the life of the unit. Follow these guidelines to keep things running smoothly:

  • Your outdoor unit should not be installed directly on the ground. They should instead be elevated to keep them out of possible snow or standing water. Apex Heating and Air does this as a standard part of our installation procedure.
  • Consider building a wind barrier with shrubs or a fence, but remember to keep them far enough away for servicing and air flow.
  • Keep the unit at least 18 inches away from the exterior wall of the house to increase air passage and to avoid drifting exposure.
  • Monitor your heat pump and outdoor HVAC systems in the winter. Snow buildup should be shoveled away, gutters should be cleaned, and ice should be melted away with warm water to prevent possible damage to the system. If it’s so cold that the warm water will refreeze, let the defrost cycle run once or twice or call one of our service technicians.

A Few Suggestions

With winter hanging around for the next few months, thermostats are working overtime. That means high heating costs for many of us, but there are ways to keep those bills as low as possible.

Here are a few mistakes you might be making and how to fix them:

  • Turning up a thermostat too high to heat a cold house quickly. When coming home to a cold house, it might be tempting to turn up the heat to try and warm things faster. But thermostats don’t work like an accelerator on a car, and turning the heat up to blistering levels won’t warm your home faster. Be patient and save money.
  • Turning the thermostat way down at night. It’s best to avoid extremes with your thermostat. If you let the temperature fall dramatically overnight, it’s going to require a lot of work from your system to warm things up in the morning—costing big bucks when the electric bill arrives.
  • Overworking a thermostat that has its limits. If you want the house to be 70 degrees, and your thermostat is only reaching 66 degrees, turning the thermostat up to 74 degrees to make up the difference could force your furnace to work beyond its capability. Instead, call Apex Heating and Air to find out what’s causing the problem. Heat could be escaping somewhere in your home or the furnace may be faulty.
  • Heating an empty house. Since we can now control pretty much everything from a phone app, the easiest way to save money is to install a system that can be adjusted remotely. Heating an empty home is a huge waste of money, so a programmable thermostat can save hundreds of dollars every year.
  • Leaving curtains closed on sunny days. While you’re away, open the curtains to allow as much warm sunlight as possible to heat the house. Solar warmth can go a long way not only in heating a house, but can help give the furnace a break during the warmest hours of the day.
  • Leaving some windows pushed up, but not locked in place. Loose or slightly open windows may allow warm air to escape (along with your hard-earned money). Enable the locks to create a seal that will keep the warm air where it belongs.

Just like shoveling snow or salting walkways, make maintenance of your HVAC system a priority this winter.

For more information on HVAC system maintenance, call (919) 467-8823 or (919) 367-0102 or click here.

About Apex Heating and Air Conditioning

Founded in 1969, Apex Heating and Air Conditioning Inc. provides complete sales and service of heating and cooling products. As a Factory Authorized Carrier® Dealer, the company is proud to offer top-notch customer service and expertise. Whether you’re in need of routine service for your HVAC system, or you require installation of a new heating or cooling system, the knowledgeable staff will work with you to ensure you’re given the information you need to make the best decision for your family or business.

(Sources: U.S. Department of Energy; The Air Conditioning, Heating, and Refrigeration NEWS; The Weather Channel; AC & Heating Connect; and The Weather Company.)