Choosing the ideal heating system for your home is essential to your comfort and can even help you save on energy costs. Those who are living in moderate climates don’t need as much heating as those who are in the northern regions. Heat pumps have become popular in these areas, especially warmer climates.
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Read on to learn the benefits of choosing a heat pump over a resistive heater.
Resistive heaters are 100% efficient because they convert all electricity into heat. However, electricity is usually made from coal, gas or oil generators that only convert 30% of the fuel’s energy into electricity. Electric heat is typically costlier than heat produced from combustion appliances due to electricity generation and transmission losses.
A centralized forced-air electric furnace or heaters in every room supplies electric resistance heat. Room heaters can consist of electric baseboard heaters, electric radiant heat, electric wall heaters or electric space heaters.
Electric furnaces are one of the costliest to operate. Because heat travels through a centralized duct system, it needs more energy to work. Also, more energy loss occurs in duct heating systems due to air leakage.
Moreover, electric baseboard heaters are zonal heaters run by thermostats in every room. HVAC technicians usually install these heaters beneath windows where rising hot air meets the cold air entering from the window glass.
It may not be apparent, but temperatures more than absolute zero have heat. It means that it may feel cool outside, but heat is still present. Heat pumps utilize electricity to circulate heat around your home, helping you stay comfortable in the cooler months.
In winter, heat pumps move heat from outdoors into your cool house, and, in summer, they move heat from your home into the outdoors. Because heat pumps move heat instead of producing it, they can cool or heat your space for as low as a quarter of the cost of running standard heating or cooling appliances.
Since heat pumps generate heat from the outside air to condition your home, their energy efficiency depends on the climate outside. This is why heat pumps are more efficient at converting electricity into heat in moderate climates. On the other hand, the efficiency of this equipment reduces in colder climates since it needs to work harder to produce the same amount of energy that usually would in a warmer climate.
Ductless Mini-Split Heat Pump
A mini-split system significantly reduces energy consumption and minimizes energy loss through the ducts. This type of heat pump doesn’t need ductwork – the reason it is called a ductless system. Among all the other types of ductless systems, mini-splits are easier to use and more convenient. Some types of ductless systems use an external heating source, such as space or water heaters that utilize propane or kerosene. With a mini-split, you can enjoy the perks of a ductless system without the risks linked to external heating sources.
Air Source Heat Pump
An air source heat pump can efficiently heat and cool your home. It can give you up to three times more heat energy than the electrical energy it uses when properly installed.
Geothermal Heat Pumps
Also called earth-coupled, water-source or ground-source heat pumps, geothermal heat pumps utilize the constant temperature of the earth as the exchange medium instead of the outdoor air temperature.
Heat pumps are the most energy-efficient in most climates in the country. Compared to electric resistive heaters, they can even reduce your energy consumption by up to 50%. High-efficiency heat pumps can cut down your home’s humidity levels better than a conventional air conditioner. This means lower energy use and better indoor comfort during the warmer months. Heat pumps are also low maintenance and have no emissions. You can even get your tax credit for using the equipment.
The cost of installing and running various kinds of heat pumps vary. For instance, geothermal heat pumps have higher installation costs than air source heat pumps. This is because, with ground-source heat pumps, you need to dig down to a heat source, and it involves more complicated heat transfer systems. The terrain on your property can also affect your project’s cost.
Operational and maintenance costs of a heat pump vary depending on the type of system. A ground-source heat pump costs less to run because ground and water have a relatively constant temperature, allowing the heat pump to work efficiently. This type of heat pump system is also not exposed to the outdoor elements, helping reduce wear and tear. Meanwhile, air source systems are easier to access and repair, but they require more maintenance since they are exposed to outdoor conditions.
Energy Efficiency
The Seasonal Energy Efficiency Ratio (SEER) determines the cooling efficiency of air source and ductless split systems. For new homes in the Northeast, Midwest, Mountain States and Pacific Northwest, the minimum is 13 SEER, and, for the rest of the country, 14 SEER is the minimum. On the other hand, the heating efficiency is measured by the Heating Seasonal Performance Factor (HSPF).
If you live in a warmer climate, you should find a heat pump with a higher SEER. The American Council for an Energy-Efficient Economy (ACEEE) recommends purchasing a heat pump that’s more than 15 SEER and 8.5 HSPF.
Moreover, the cooling efficiency of geothermal heat pumps is rated by Energy Efficiency Ratio (EER) while its heating efficiency is rated by the Coefficient of Performance (COP). Depending on the type of system, the federal EER minimums are 17.1 to 21.1, and COP minimums are 3.1 to 4.1.
Size
Another thing you should consider when choosing a heat pump is size. Undersized or oversized equipment would affect your indoor comfort and increase your energy consumption. For instance, if the unit is too big for your home, it will cycle on and off many various times, reducing its lifespan.
A skilled HVAC contractor can help you choose the ideal heating and cooling system for your home. For quality air conditioning repair and installation services, turn to EZ Air Conditioning and Heating. Call us at (210) 558-7883, or fill out our contact form to learn more about our services.
Sometimes companies that make products stretch the truth, embellish features, or rely on their potential customers’ ignorance of how things work. Shocking, I know. The world of electric heating has such companies. But if you’re looking for a device that will provide electric space heating for your house, it’s actually pretty simple to figure out the truth.
Electricity is a marvelously versatile way to move energy from one place to another. One of the most important things to understand about it, though, is that it’s not an energy source or fuel, like natural gas. It’s an energy carrier, whose source is the heat of burning coal, the motion of water rushing through a hydroelectric turbine, the movement of electrons and holes in semiconductor photovoltaics, or some other energy conversion process. At the other end of the electrical system, electricity gets converted again, this time into heat, light, or some other form of energy in our homes and workplaces.
We have two primary methods to use electricity to provide space heating: electric resistance or heat pumps. Let’s look at them separately.
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Electric resistance heating. Also called Joule heating or ohmic heating, it simply wrings the energy out of the electricity and turns it into heat directly. For every one unit of electricity, you get one unit of heat. Starting with Count Rumford’s experiments showing that mechanical energy and heat are equivalent, scientists have shown that all forms of energy can be converted from one to another. (Rumford, despite the title, was an American who deserted his country and his wife to fight on the losing side of the American Revolution.)
And that’s where the law of conservation of energy comes in. To convert energy from one form to another, you have to end up with the same amount of energy you started with. Looking at the conversion factor for the units of electrical energy (in kilowatt-hours, kWh), we see that the amount of electrical energy that can be converted to heat (in British Thermal Units, BTU) is:
3,412 BTU per kWh.
So, with electric resistance heating, we’re simply converting the energy in the electricity to heat, and the number above represents the ultimate reality of the conversion. It’s a one-to-one energy transformation. One kWh of electricity in yields 1 kWh of heat out, and 1 kWh of electricity equals 3,412 BTU. You can’t get 5,000 BTU/kWh with electric resistance heating because that would violate the law of conservation f energy. Another way to say this is that electric resistance heating is 100% efficient, which makes it sound pretty good . . . even though it’s not.
An electric resistance space heater will deliver 3412 BTU of heat for each kWh of electricity used. The same is true of an electric furnace, a toaster oven (photo above), and a standard electric water heater. But there is a way to convert electricity to heat at better than a 1:1 ratio.
Heat pump. If you take that same electricity and put it into a heat pump, you can deliver more than 3,412 BTUs for each kWh of electricity you use. The reason is that you’re not doing a simple conversion from one form to another. You’re using the electricity to do work. It runs a compressor that moves refrigerant through a system that transfers heat from a cooler place to a warmer place. And it can move 3−5 as many BTUs/kWh as electric resistance gives you. My Mitsubishi heat pump has a rated efficiency of about 4:1, so it can send about 14,000 BTUs of heat into my house for each kWh of electricity I use.
(In case you’re wondering, there is another method of heating deserves mention here, too: the induction cooktop. It’s not electric resistance and not a heat pump, but it does essentially the same thing as electric resistance. It uses the energy in electricity to create heat in the cookware, so, like resistance heat, it’s 100% efficient at converting electricity to heat. It’s just better at putting the heat exactly where it’s needed.)
A 1,500-watt electric space heater provides 5,119 BTUs per hour (1.5 kW x 3,412 BTU/kWh). But that doesn’t stop companies from putting them in fancy packaging and using confusing language to make people believe they’re getting something “miraculous.” Take the Amish fireplace, for example. It’s just a 1,500-watt space heater with an Amish-made mantel.
If you need something bigger, there’s the electric furnace. Common in places like Florida that don’t have much of a winter, these devices again use electric resistance heating. It’s 100% efficient, as is the simple space heater and Amish fireplace.
Here are some things to look out for when evaluating efficiency claims for electric heating systems.
1. Misleading comparisons. Newspaper ads for the Amish fireplace compared it to a coffee maker. That’s just another form of electric resistance heating, with the same 100% efficiency. Interestingly, they said it uses less energy than a coffeemaker, but the current specs for a Mr. Coffee rate it at 900 watts, significantly less than the 1,500 watts of the Amish fireplace.
One that I came across recently is the Cocoon Thermasi electric furnace. Although they do a good job of camouflaging it, the source of the heat seems to be electric resistance. That makes it 100% efficient in converting electricity to heat, just like any other furnace. They claim, however, that it “uses up to 41% less energy than a traditional electric furnace.” More on that in a bit. The most important thing to note, though, is that they’re comparing their product to electric furnaces, not heat pumps.
Another way to mislead by comparison is to use the old apples-and-oranges trick. An electric furnace is 100% efficient, whereas a gas furnace may be only 80% efficient. But you can’t compare the direct burning of a fuel onsite to heating with electricity brought in from a power plant. Coal-burning power plants, which still provide much of our electricity in North America, are only about 35% efficient. So there’s an efficiency multiplier effect here that makes a 100% efficient electric furnace only about 35% efficient when you consider the source.
2. Using technical terms without much explanation. The Cocoon Thermasi electric furnace does this well. Thermal mass, control algorithms, controllable infrared heat spectrum . . . It’s easy to use this type of language to fool people who don’t have science or engineering backgrounds. It sounds impressive, right? Once you understand that there are really only two ways to heat a house—electric resistance and heat pumps—you can cut through the nonsense. Which category does it belong in? In this case, it’s electric resistance: 3,412 BTU/kWh. It’s not a heat pump, which can be 10,000 BTU/kWh or greater.
3. Muddying the waters between total energy use and rate of energy use. Energy and power have led to a lot of confusion. Energy, measured in kWh, is what you pay for when you get your electric bill. Power, measured in watts or kilowatts, is the rate at which you use that energy. A 1,500-watt space heater might well use less energy than a 15 watt LED light bulb over the course of a month. It depends on how much time each operates. If you use the space heater for one hour and the light bulb for 200 hours, yes, the space heater uses less energy: 1,500 watt-hours vs. 3,000 watt-hours. (This is a doubly clever trick because it also uses method #1 by throwing in a misleading comparison.)
Alternatively, a product could use more energy and claim to be more efficient by using less power. All you need is to find an appliance that cycles on and off when it’s heating. By reducing the amount of time a product is off, you can use less power for a longer time, and then point to the power use, not energy consumption, to claim higher efficiency.
Although the Cocoon Thermasi electric furnace descriptions are spare on details, I believe this is what that product does. Thermal mass, once it’s heated up, allows you to use less power because you can draw out some of the stored heat when there’s a call for heat. The UL page “verifying” the manufacturer’s claim, also spare on details, indicates that their test was based on power: “The power usage results for equal air flow and heat rise were compared among the three units.”
Once you understand that all-electric heating uses one of the two methods above—electric resistance or heat pump—it’s a lot easier to sort through efficiency claims. If it’s electric resistance, you’re not going to get more than 3,412 BTU/kWh. Period. If it’s a heat pump, the same electricity can move 10,000 or more BTU/kWh. That’s why Georgia, my home state, banned electric furnaces used as primary heat sources a decade ago.
As I mentioned at the outset, electricity is a great energy carrier. It keeps getting cleaner every year, and it’s the key to getting away from fossil fuels. It’s also the best way to do zero-energy homes, which is my goal for the home I live in and the reason I got rid of my gas meter.
But we have to be smart about how we use electricity, which means using electric resistance heat only in places where it makes sense. We’re never going to have a heat pump toaster oven, but for space heating, water heating, and even clothes dryers now, heat pumps are the way to go.
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Allison Bailes of Atlanta, Georgia, is a speaker, writer, building science consultant, and founder of Energy Vanguard. He is also the author of the Energy Vanguard Blog. You can follow him on Twitter at @EnergyVanguard.
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