Heat Pumps: The Energy Efficient Alternative to AC Units
It’s ten o’clock in the morning, and already eighty degrees. That’s when you begin thinking about the words “air conditioning” the most.
Those are the days when you’ll do anything to stay cool. Those are the days when you make plans to do everything on the inside, thankful your air conditioner is working full time.
But what about the efficiency of today’s AC units? Depending on how old your HVAC system is, it might not be as energy efficient as it could be. Which may leave you wondering what alternatives you have to staying cool and being a little greener in the process.
A heat pump may be the answer.
Don’t get confused by its name. A heat pump can both heat and cool, using a small amount of energy to move heat from one location to another. Heat pumps can pull heat out from the ground or the air, and push it into a house or a building to heat the surrounding area. A heat pump can work in reverse as well, moving the heat inside a house or building, and pushing it outside and away from your living space.
One of the biggest advantages of using a heat pump instead of your standard HVAC system is that there isn’t a separate system for heating and cooling your home. It’s all tied up in one neat and easy to use system. Heat pumps are extremely efficient because they simply transfer heat. They don’t burn fuel to create heat, which makes a heat pump more environmentally friendly than it’s gas burning alternatives.
Heat pumps work best in moderate weather conditions, where you don’t face extreme heat or cold conditions throughout the year. Which makes heat pumps a viable alternative here in the Pacific Northwest where we rarely see the extremes.
There are many different kinds of heat pumps, but in general, they operate in the same way. Rather than burning fuel to create heat, the heat pump moves heat from one place to another. The heat pump uses a small amount of energy to pull heat out of a low temperature area, and pump it into a higher temperature area. So heat is transferred from a heat source, like the ground or air, into a heat location, like your home.
Air-Air Heat Pumps
One of the most common types of heat pumps is the air-source heat pump, or air-air heat pump. This heat pump takes heat from the air outside your home and pumps it through refrigenant coils in a similar manner as your refrigerator.
The air-air heat pump takes heat from outside and transfers it to indoor air ducts. What allows the air-air heat pump to also cool is the reversing valve. When triggered, the heat pump reverses the flow of refrigerant so that the system operates in the opposite direction, taking the heat inside your home and pumping it outside, just like your air conditioner. This process continues to repeat until your home is cooled to your desired temperature.
Air-source heat pumps have two sets of refrigerant coils that transfers heat indoors, where it’s blown away from the coils by a fan, distributing it as cold air throughout your home. While you’ll typically find air-source heat pumps in a single box unit on commercial properties, usually on the roof of a building with the ductwork extending through the wall, you’ll normally find home air-source heat pumps as a split system with an indoor and outdoor component installed through the wall. Depending on the unit, there may be one or more indoor components to distribute conditioned air.
Ground-Source Heat Pumps
Ground-source heat pumps work a little differently. They absorb heat from the ground and transfer it indoors, or vice versa for cooling. The most common ground-source heat pump transfers heat from the ground by absorbing it through buried pipes filled with water or a refrigerant liquid piping system, either in a closed-loop or open-loop system. Closed-loop uses the same refrigerant and water to circulate through the system again and again. Open-loop systems use water pumped from an underground water source, extract the heat from the water and that water returns to the underground resource.
Absorption Heat Pump
A third type of heat pump – absorption heat pumps – are powered by natural gas, solar power, propane, or geothermally heated water. The main difference between an air-air heat pump and an absorption pump is the use of refrigerant for the heating and capturing process. Instead, an absorption heat pump absorbs ammonia into water, and then a low-power pump pressurizes it. A heat source boils the ammonia back out of the water, and the process begins again.
Other Heat Pumps
A mini-split heat pump can be used if your home wasn’t designed with air ducts in place. A mini-split heat pump connects an outdoor unit to multiple indoor units. It’s easy to install these anywhere because their indoor and outdoor locations can be placed anywhere. They are also very small in size, requiring only a 3 inch conduit to come through the wall.
A reverse cycle chiller heat pump heats water instead of air and can operate efficiently when temperatures fall below freezing. The reverse cycle chiller heat pump connects to an insulated water tank that heats or cools. It works in a similar manner from that point forward, sending conditioned air wherever you desire. With a reverse cycle chiller heat pump, you can also send hot water through radiant floor heating to give a warm floor during the cold winter months.
While heat pumps have been around for many years, technological advances have been made, making them even more beneficial for heating and cooling your home.
Many heat pumps today use a two speed compressor that allows heat pumps to operate close to the heating or cooling capacity needed. This helps save electrical energy, as you only use the pump to produce the conditioned air you desire, and it also reduces compressor wear.
Some models are equipped with variable or dual speed motors that allow fans to keep the air moving at your preferred velocity, which helps eliminate cool drafts and maximizes electrical savings. It also helps cut down on the noise that is sometimes associated with a blower operating a full speed.
If you choose a high efficiency heat pump, it may have a desuperheater, which recovers unused heat created during the cooling mode, putting it back into the system to help heat the water. This process can heat the water up to three times more efficiently than an ordinary water heater.
Advanced heat pump technology is now installing a scroll compressor, which compressed the refrigerant by forcing it into increasingly smaller areas. Compared with a typical compressor, these scroll compressors have a longer operating life and provide quieter function.
As with any HVAC equipment, actual energy savings depends on many things.
Is it time to look at installing heat pump technology into your home?