A heat pump works by transferring heat from one location to another. It looks much like an air conditioner but can provide heating or cooling depending on the setting. Heat pump installation is more common in milder climates, as most units would require a supplemental heat source if it gets too cold outside. We’ll now more thoroughly answer the question, “How does a heat pump work?” and explain the different types available.
How a Heat Pump Heats or Cools a Home
A furnace works hard to create heat. An air conditioner cools the air using a mechanical process. However, a heat pump works by redistributing heat rather than creating it. Ambient heat from the air or ground is transferred to the refrigerant, which flows through the indoor coil. A fan helps bring warm air into your home. But in cooling mode, the system works in reverse. It absorbs heat from inside your home and the refrigerant moves this heat to the outdoor unit, where a fan helps release it outside.
The system moves heat by changing the pressure of the refrigerant. This fluid readily absorbs heat at low pressures and evaporates into a gas. Meanwhile, gaseous refrigerant has a higher energy level than the outside air at high pressures. Therefore, it can pass the heat to the surrounding air. The cooling process helps condense it back into a liquid.
Thus, in summer, the unit works as follows:
- Warm air from indoors blows across the refrigerant coil.
- Heat is absorbed by the liquid, which evaporates into a low-temperature gas.
- Cooled air is released into your home.
- The refrigerant, in vapor form, passes through the compressor.
- As a hot, high-pressure vapor, refrigerant moves through the outdoor coil and releases heat into the outdoor air.
- Now a high-temperature liquid, the refrigerant passes through an expansion valve. This relieves pressure and reduces the liquid’s temperature.
- Low-temperature, low-pressure liquid refrigerant is pumped back to the indoor unit.
The heat pump works the same way in heating or cooling mode. A reversing valve enables it to switch from one mode to another. Even when the outdoor temperature is relatively low, the system can draw heat energy from it and release it into your home. And it can transfer heat outside no matter what the outdoor temperature is.
When switching from cooling to heating mode, the function of the indoor and outdoor coils reverses. The indoor coil becomes the condenser and the outside coil becomes the evaporator.
Air Source Heat Pumps
Air source units are the most common. A typical air source system has an outdoor unit with a coil and a fan that facilitates heat exchange. The indoor unit is an air handler with a coil and fan that moves air through the coil and into the ductwork. Other key components include the compressor, an expansion valve that regulates refrigerant flow, and a reversing valve.
Together, these components allow the heat pump to pull heat from or release it outdoors. The system works much like a standard refrigerator.
Ground-Source Heat Pumps
While air-source heat pumps are split systems with outdoor and indoor components connected by a conduit, ground-source systems work a little differently. The most common design consists of a network of buried pipes that use water or refrigerant to absorb heat from the ground.
A closed-loop system circulates the same water or refrigerant in a repeating cycle. An open-loop system pumps water from an underground source, extracts heat from it, and returns the water to the same source. More water is pumped from the well to extract more heat.
Absorption Heat Pumps
Absorption heat pumps were once reserved for large-scale applications. However, they’re becoming more practical for homes. The system is powered by natural gas, propane, geothermal-heated water, or solar energy. An absorption system does not compress refrigerant; instead, it absorbs ammonia into water and a small pump pressurizes the liquid. The heat transfer process occurs as ammonia is boiled out of the water in a constant cycle.
Mini-Split Heat Pumps
A heat pump doesn’t necessarily need ductwork to distribute conditioned air. A mini-split heat pump connects multiple indoor air handlers to a single outdoor air-source unit. The locations for the indoor and outdoor units are flexible. The conduit connecting them requires just a 3-inch hole to be drilled in an exterior wall.
Contact Monarch Home Services
“How does a heat pump work?” is becoming a more common question for homeowners. Central California’s climate is well-suited for heat pumps. Our indoor climate specialists can determine the size and type of unit needed and provide heat pump installation, repairs, and maintenance. High-quality service ensures you see lower utility costs and experience other benefits of installing a heat pump. To learn more, call (661) 215-6745 or contact us online.