Most Chicago area residents have a traditional furnace and air conditioner. While this setup certainly gets the job done, it may be inferior to another option: heat pumps. Before you upgrade your home’s HVAC system, consider this alternative to the conventional furnace/air conditioner arrangement.
How Do Heat Pumps Work?
An air-source heat pump is a year-round heating and cooling system that runs on electricity. In the summer, heat pumps act exactly the same as central air conditioners. A compressor pumps air inside your home over a coil filled with refrigerant. This refrigerant absorbs heat from the air and expels the heat outside. The cooled air exits supply registers and your home stays comfortable.
Thanks to a reversing valve, the process works in the opposite direction when it’s cold outside. Even as the temperature drops, outdoor air still has heat the refrigerant can extract and expel into your home to keep you cozy in the winter.
Keep in mind that standard air-source heat pumps have a decreased capacity when the outdoor temperature drops below freezing. At this point, some type of backup heat – such as electric-resistance heating or a gas-fired furnace – may kick on to maintain a comfortable indoor temperature. (Increasingly, modern heat pumps are providing comfortable heating at lower temperatures without having to resort to emergency backup heating.)
It’s important to recognize that heat pumps are not a form of ventilation. The air that exits supply registers is the indoor air being re-circulated, not outdoor air being introduced into the home. If you want fresh air brought inside, your best option will be a whole-house ventilation system.
Types of Heat Pumps
Several types of heat pumps are available to keep your home comfortable all year round. These include:
- Air-source heat pumps are the most common type as described at the beginning of this article. These units most closely resemble air conditioners. Most are split-system units, meaning they include an outdoor compressor/condensing unit and an air handler inside the house that contains the indoor coil. Heated or cooled air is delivered by a fan that circulates it through ductwork and out supply registers around your home.
- Geothermal heat pumps are different from air-source heat pumps, although they are also powered by electricity. But instead of transferring heat from the air inside and outside the home, geothermal heat pumps absorb heat from the earth for indoor heating, or for cooling release heat back into he earth. Pipes buried underground, which usually carry a water/anti-freeze mixture, extract heat and deliver it to the interior through ductwork (heating), or remove heat from the home and reject it back into the earth (cooling).
- Absorption heat pumps are powered by natural gas, propane, solar energy or geothermal-heated water. They are usually reserved for large commercial or industrial applications, though they are sometimes used in very large residences.
- Ductless mini-split heat pumps can be used for entire homes or as add-ons without ductwork. Air conditioning can still be enjoyed as well with ductless mini-splits. They have two major components, the same as air-source heat pumps, but one or more interior air handlers have a blower built in so that air is delivered on the spot for zoned heating and cooling. You can switch from heating to cooling with the touch of a button for quick temperature changes.
How Efficient Are Heat Pumps?
Conventional heating appliances usually burn a fossil fuel to produce heat. The laws of physics restrict combustion heating to no more than 100 percent efficiency. If that’s not good enough for you, rest assured that air-source heat pumps deliver 170 to 330 percent efficiency, depending on the unit’s efficiency rating, routine maintenance, and the outdoor temperature.
How is this possible? Heat pumps move heat with electricity, rather than generating it directly. This makes it possible to move four units of heat with only one unit of electricity.
The exact efficiency of a heat pump depends on specific features the unit possesses. To enjoy the greatest efficiency possible, seek out a heat pump with the following advanced features:
- Thermostatic expansion valve: The TXV more precisely controls the refrigerant flow to the indoor coil. That way, heating and cooling demand is regulated based on specific conditions, thus saving energy.
- Variable-speed blower: This allows the heat pump to operate at multiple speeds. Picture the air conditioner in your car. If you only had two choices – high speed or off – you would find yourself continually adjusting the temperature. This is what happens in a home with a single-speed blower. The ability to operate at multiple speeds keeps your home at a steady temperature while saving energy by not cycling on and off so frequently.
- Two-speed compressor: A two-speed version can run at lower capacity when it’s mild outside. Then when demand increases, the compressor kicks into high gear. The ability to run at the lower speed most of the time saves energy.
- Demand-defrost control: Winter temperatures in the Chicago area can plummet, which may cause the outdoor compressor to freeze. Without demand-defrost control, a heat pump performs routine defrost cycles based on a timer, whether ice is present or not. This advanced feature senses when ice is building up and only calls for defrost cycles when they’re actually necessary.
- Hybrid heat thermostat: You may be familiar with the concept of setting the temperature back while you’re away or sleeping to save energy. This concept does not work if you use a traditional manual or programmable thermostat with a heat pump because the less efficient backup heat source will kick on to restore a comfortable temperature when you bump up the temperature more than a couple degrees at a time. This negates your efforts to save energy. However, Hybrid heat thermostats are made to work with heat pumps. They ask for gradual temperature changes from the heat pump so the backup heat source doesn’t turn on.
- All-climate technology: Chicago doesn’t exactly have the climate of a tropical paradise. It’s often well below freezing for long stretches of time in the winter. Standard air-source heat pumps count on backup electric-resistance heating in these situations, which is much less efficient. More advanced all-climate heat pumps can reduce heating costs in Chicago’s cold climate by 25 to 60 percent compared to standard heat pumps. They feature a two-speed, two-cylinder compressor, back-up booster compressor and other features that allow for efficiency down to 15 degrees. A plate heat exchanger further extends performance well below 0 degrees.
Advantages of Heat Pumps
With so much to consider, how do you know if a heat pump is really right for your Chicagoland home? Consider the benefits:
- Lower energy bills: How would you like to keep your home as comfortable as possible with substantially lower energy bills? Heat pumps deliver that advantage.
- Heating and cooling from a single unit: It could certainly be in your best interest to choose a heat pump if your existing furnace and air conditioner are both on their last legs. The cost to purchase a single piece of HVAC equipment and a backup heat source could be a much more affordable option.
- Safer heating: Combustion heating appliances produce carbon monoxide as a byproduct, resulting in a risk for CO poisoning. This danger does not exist with heating equipment powered by electricity.
- Healthier environment: Energy-efficient heating and cooling doesn’t just mean lower utility bills; it also means fewer greenhouse gas emissions and a cleaner environment. Also, new heat pumps run on environmentally friendly R-410A refrigerant while it’s likely that your outdated A/C still uses the more harmful R-22 refrigerant (Freon).
- Convenient climate control: In homes with a traditional HVAC setup, the air conditioner is reawakened every spring and retired every winter. If you jump the gun, you could end up with discomfort as the seasons change. A heat pump, on the other hand, lets you change from heating to cooling for daily home comfort, even when the seasons are in transition.
Disadvantages of Heat Pumps
It’s also important to consider the other side of the coin. Heat pumps have the following downfalls:
- Lower efficiency when the temperature drops: This is perhaps the primary reason heat pumps often take a backseat to furnaces and air conditioners. Fortunately, with advanced all-climate heat pumps becoming more available, this disadvantage is diminishing.
- Noise: Heat pumps tend to run longer than furnaces; in fact, they run almost constantly in very cold weather. This can lead to constant background noise you may find disruptive.
- Drafts: Air coming from the supply registers is sometimes lukewarm in the winter. While this helps keep the home at a constant temperature, it can feel drafty if you sit right in front of a register. Some people prefer the cozy warmth of gas heat.
Operating and Maintenance Tips
If you decide a heat pump is right for you, don’t forget these important operating and maintenance tips to get the most from your investment:
- Change the air filter every month.
- Schedule preventative maintenance every spring and fall.
- Check for leaky ductwork and have a technician seal any leaks.
- Check for leaks in the refrigerant line and have them fixed right away.
- Clean the outdoor coils when they appear covered with dirt. Straighten the fins when necessary.
- Remove grass clippings or dead leaves that stick to the outdoor unit.
- Trim vegetation back at least 18 inches from the outside unit to ensure proper airflow.
For answers to any remaining questions about heat pumps, please contact us at Comfort24-7.com.
Written by Randy Gailit