Heat Pump Options
You’ve heard of heat pumps, and about how efficient they are; how they can potentially cut your heating and cooling costs. But maybe you’re confused by the concept and all the bells and whistles you’ve heard. Let’s talk about heat pumps and some of the add-ons that can go with them.
How a heat pump works
A heat pump transfers heat rather than generating it. That is the basic working principle. Even in the hot summer, heat from inside the house can be dissipated outside. And even in winter, there is enough warmth in the outside air to gather and use.
The system circulates a chemical refrigerant that is sometimes gas and sometimes liquid. A combination of valves, compressors, and condensers gets the refrigerant to the right conditions to lose or take on heat. In summer an expansion valve cools the refrigerant just before it enters the home. In winter a different expansion valve makes the outside coils suck in ambient heat that can then get pumped to the inside unit.
Basically, it uses the science of how compression and expansion change the temperature and physical state of some chemicals. It’s sort of like blowing on food to cool it down. The air escaping your mouth decompresses and cools a little bit. Because it has so much less machinery than a conventional system, it saves electricity and money. Compared to many conventional systems, savings may be up to 50%.
What kinds of heat pump are there?
The three main types are air source, water source, and geothermal. They all work by circulating a refrigerant through the lines – heat transfer instead of heat generation. Geothermal and water source both involve burying the lines underground, while air source keeps them within the unit. As a result air source is cheaper to install. Water source and geothermal still have lower operating costs, though, because underground temperatures are more stable than air. Ground and water source also work better in colder regions with frequent freezing temperatures.
What are other heat pump options?
Regardless of where the heat transfer begins and ends, there are other options that can go into almost any heat pump system. Let’s look at some of them.
- Dual speed compressors. A standard compressor operates at one capacity regardless of what the circumstances call for. By including a speed below full capacity, dual speed compressors save energy whenever the temperature does not need them on full blast. Saving energy saves money.
- Variable speed fans. These are like the dual speed compressors. Instead of only working at one speed, these fans can vary energy use according to current conditions. Again, energy and money saved.
- Desuperheaters. A device that gathers waste heat from air conditioning, which would normally be dispersed outside. This salvaged heat can be used to heat water, and are sometimes more efficient than standard hot water heaters.
- Scroll compressors. Most compressors work with a piston on a revolving wheel, a concept that goes back to the discovery of steam power. Scroll compressors have two sheets inside them, rolled like scrolls so that when one moves inside the other it pressurizes the contents. They have fewer small moving parts than piston compressors, so they have a longer operating life. They are also quieter, and systems with them produce 10-15 F more heat than piston compressor systems.
If you get a heat pump, the kind you should get depends a lot of climate and soil conditions (pdf) where you live, as well as on your budget. You’ll want to consult with experienced HVAC professionals before making that decision. If you are considering a heat pump for your home, give Twin Air a call at (703) 754-1062 or visit us online.