Is Covering Your HVAC System in Winter a Good Idea?

HVAC Unit in Kirkland, WA

The benefits of winter coverings for HVAC systems have long been a subject of debate. There are many valid arguments both for and against putting covers on outside heating and cooling equipment when the weather grows cold. Determining what’s right for the system that you use in your Seattle, WA home is essential. The following deals with everything you need to know about covering HVAC systems during the cold season.

Heating and Cooling Equipment Types Are Important

Given its large number of historic properties and due to its longstanding reputation for year-round rainy weather, Seattle is one location where traditional central HVAC systems aren’t exactly the norm. Many households have radiators and baseboard heaters, ceiling fans, and little else. To modernize older properties, a lot of homeowners have installed ductless mini-split air conditioners or ductless mini-split heat pumps. There are also a number of buildings that are still reliant upon old and inefficient window air conditioners for summertime cooling.

With this in mind, it’s important to note that the value of using heating and cooling system covers varies from one equipment type to the next. For homes with central HVAC systems that provide both whole-house heating and whole-house cooling, covering outdoor AC condensers is rarely recommended. AC condensers are permanently installed outside and thus, they’re designed to withstand the natural elements. AC manufacturers anticipate that this equipment will be exposed to wind, rain, sleet, snow, and more. Even the sensitive coils that are inside an AC’s condensing unit can hold up well during extreme winter weather.

However, window-mounted air conditioners are quite different. These units are designed for spring and summer use only. When fall arrives and the outdoor temperatures start to plummet, these units should be taken down, cleaned, covered, and placed in storage. In short, recommendations against covering outdoor heating and cooling system components do not apply to all system types. To be sure about what your equipment requires, contact an HVAC company, check your owner’s manual, or speak directly to the equipment manufacturer. This is also a good idea for certain outdoor heat pump components.

Why AC Condenser Covers Aren’t Necessary in Western Washington

When people ask whether they should cover their HVAC systems in winter, they’re really talking about their AC condensers. Unless temperatures in Western Washington take an unexpected turn before the arrival of spring, these units will remain dormant from approximately late October until mid-March or early April. Although Seattle and the greater King County area aren’t known for having heavy snow loads throughout this time, there are years when several inches of snow accumulate.

The goal of covering an AC condenser during winter is to prevent snow melt, rain, and other forms of precipitation from entering this component. However, even the characteristically heavy rains of the region won’t cause condenser damage. Moreover, if it does snow in Seattle and if snow loads are heavy, the best thing that you can do for your condenser is to simply brush these accumulations off. This is something that you can take care of when shoveling your walk or clearing your roof. Much like roof clearing during the winter months, snow removal at the AC condenser should be performed gently and with a lightweight brush or broom rather than a shovel or ice pick. It’s also a good idea to get rid of accumulated snow before it melts and refreezes.

Why Condenser Covers Can Do More Harm Than Good

Given that AC condensers are built to be weather-resistant and due to the fact that all heavy precipitation can be regularly and easily cleared away, covers for these units aren’t necessary. In fact, not only are they nonessential, but AC condenser covers can actually cause far more problems than they resolve. This remains true whether you fashion your own cover out of tarps or plastic or purchase one that’s been specially designed for the air conditioner model that you own.

Efforts to create a watertight barrier between condensers and the outside world wind up trapping minor amounts of moisture inside. In fact, even seamless covers will allow small amounts of new moisture in. This creates condensation on the interior of condenser covers and increases the likelihood of rusting. If you put a cover on your outdoor HVAC equipment at the start of winter and leave it on until spring arrives, your condenser will probably be riddled with corrosion when you finally take the cover off. AC condenser covers aren’t set-it-and-forget-it solutions for AC winterization.

Is There Ever a Good Time for HVAC Covers?

Just as there are many arguments against using condenser covers, there are a few solid arguments for putting them on. For instance, if a major storm is coming that will include heavy winds, lots of freezing precipitation, and ultra-low temperatures, short-term use of a quality condenser cover might not be a bad idea. A good cover will prevent rocks, twigs, and other fast-moving debris from causing damage to the unit. However, as soon as the storm has passed, this cover should be immediately lifted off and the underlying equipment should be allowed to dry. Blocking airflow around the unit for more than two to three days at a time is bound to result in rust.

Structural Barriers Versus Covers

It’s additionally important to note the difference between structural barriers and covers. Condensers should always be strategically installed. When HVAC companies account for weather-related challenges, they choose locations for AC condensers that will provide plenty of shade in the summer and ample structural protection in the winter. This way, condensers won’t overheat when they’re needed the most, and they’ll be unlikely to sustain impact-related damage when they’re dormant. For instance, if you have a large, open backyard, your AC condenser may be positioned close to the fence that travels around the perimeter of your lot. This fence will prevent gravel and other debris from blowing into the condenser. It will also serve as a source of shade in the summer.

In regions that regularly have freezing winter temperatures, HVAC companies position AC condensers sufficiently far away from buildings to prevent damage from falling icicles. But what about impact-related damage caused by cold winter weather that isn’t easy to avoid? For instance, what happens when hailstorms pass through the Seattle region and AC condensers are left uncovered? For problems like these, structural barriers are far preferable to soft-sided covers. These can include partial enclosures made from wood, full enclosures, and roofed enclosures as needed. Unlike plastic covers, wooden enclosures won’t block airflow and they won’t increase the likelihood of rust.

The Best Way to Winterize and Protect Your HVAC Equipment

Before covering or enclosing your AC condenser, it’s always a good idea to check your warranty documents. Due to the high likelihood of condensation and corrosion when using or misusing AC covers, some manufacturers strictly forbid it. It’s also a good idea to consult with an HVAC technician before purchasing or fashioning a cover for your AC condenser. Your HVAC equipment may have specific requirements for ventilation even if a cover is only being used for two to three days at a time.

For more than 20 years, Black Lion Heating & Air Conditioning has been proudly serving residents of Seattle and the surrounding areas. We provide heating and cooling system installation, maintenance, and repair services. King County locals can also turn to us for water heater, air duct cleaning, indoor air quality, and electrical services. If you need help winterizing your home’s HVAC equipment, get in touch with us today.