Step 25- Install the Heating Appliances
One of the things I was most excited about, yet also most apprehensive about, was installation of the heat pump. Installation of refrigerant systems like AC units and heat pumps is a delicate process and requires quite a few expensive tools. Refrigerant gas leaks are odorless yet can be very dangerous to ones health. That having said, heat pumps are absolutely incredible innovations and it is completely mind boggling to me why more people don’t have one. The average American has a natural gas furnace to heat their home with an efficiency of about 85%, meaning that only 85% of the energy you pay for electricity to power it is used to heat the home. The rest is lost out of the exhaust duct. Then, they have an entirely separate machine, an air conditioner, to cool their home. The heat pump replaces both of these units with a single, wonderful machine that is up to 300% efficient! That means that three times as much energy as you power it with is created to heat the room. Now, you might recall from your high school physics class that energy cannot be created or destroyed, so how could a heat pump possibly create more heat than the energy that is put into it?
The answer is that a heat pump doesn’t create heat at all! It uses the small amount of energy you power it with to MOVE heat. When you want to cool the house it takes heat from inside your house and moves it outside. When you want to heat, it takes heat from outside your house and moves it indoors. Now you might be wondering, when I want to be heated, it is usually cold outside. How could a heat pump possibly find heat outside on a cold day to move indoors? The answer to this is that heat is relative. If it’s 20 degrees Fahrenheit outside, that may seem cold to you and me, but that might be a warm day for someone in Antarctica. On a cold day, there may not be as much heat outside as on a warm day, but there has to be some heat or the temperature wouldn’t be able to get any lower. In fact, the temperature at which no heat exists is -459.67 degrees Fahrenheit. Now THAT’S cold!
So a heat pump moves heat. The unit I purchased by Fujitsu is the most efficient unit you can buy at the moment, and it has the ability to find heat even when it is -15 degrees Fahrenheit outside, which would be virtually impossible in the area where I am building. The way it performs this function is quite complex, but I will drastically simplify it for you. First, you have to understand the simple law of physics that says temperature and pressure are directly related. If you have ever used a pressurized spray can before you might recall that the can gets colder as you are spraying. This is because the pressure inside the can decreases as the contents are sprayed out. The lower pressure inside the can results in a lower temperature.
So my heat pump has a long copper tube full of refrigerant called R410a. When you want to heat up the house, the refrigerant moves through the tube from inside the house to outside, where a fan blows air across it. Even though it is cold outside, the refrigerant is even colder so it warms up as the fan blows air across the tube. That refrigerant is then run through a compressor, which pressurizes it, so it becomes very hot. The refrigerant runs through another tube back inside the house where a second fan blows air across it. The refrigerant is now very hot, so the air warms as it blows across the tube, and the refrigerant cools off. The refrigerant then travels to what is called an expansion valve, where the volume of the tube holding the refrigerant increases. This reduces the pressure of the refrigerant, in turn lowering its temperature. At this point the refrigerant has returned back outside to where it started it’s journey and the process repeats itself. The only energy the system needs are to run the compressor, the fans, and the controls. None of the energy is used to create heat, and the energy required to operate the machinery is much less than the energy required to create heat.
To cool the air in the summer, the heat pump uses a valve that allows it to reverse the process, moving heat from inside the house to the outside. It’s that simple! There are several performance ratings for heat pumps. The SEER rating is a measure of how efficient the unit operates in the summer, and the HSPF is a measure of how efficient it operates in the winter. If you can find a unit with better ratings than mine, please let me know! To my knowledge it is the most efficient unit you can buy.