As heating and cooling technology gets more sophisticated, clients are asking builders to help them find the best options for their buck. Ultimately, the right choice depends on climate, utility prices, and available fuel sources, not to mention return on investment. And as direct-vent, high-efficiency furnaces become the norm, hybrid heating systems can be a savvy solution in cold or mixed-temperature climates.
“Hybrids have been around for a while, but they’re becoming more prevalent,” says Tim Heitz, sales manager of JK Mechanical in Lancaster, Pennsylvania. “Heat pumps are efficient to a certain point, but when temperatures dip below 35 degrees, their efficiencies start to die pretty fast.”
Here’s how a hybrid, or dual-fuel, unit works: An electric heat pump (air source or ground source) is combined with a propane or natural gas furnace, and the system draws on one or the other fuel source depending on the outside temperature. Electricity costs rise sharply with the use of electric resistance backup heat, which kicks in when temperatures fall below about 35 degrees. When the thermometer drops, a hybrid unit will automatically switch over to the high-efficiency propane furnace, which improves energy efficiency, lowers utility costs, and provides greater indoor comfort.
Homeowners like having that choice, says Tom Archer, senior product manager for heating products and indoor air quality at Carrier. “In the north, people use a heat pump and high-efficiency furnace together because over the last decade or two, we’ve seen massive fluctuations in gas and electric prices,” he says. “We predict we’ll continue to see them move up and down. You can adjust the cutover point between the heat pump and furnace so you’re getting optimal economic and comfort balance.”
As energy prices fluctuate, homeowners can determine the point at which switching over will save the most money, Archer adds. It’s also a matter of comfort. If they prefer the warmer air delivery of the furnace, they can adjust the transition point up or down. The furnace lasts longer too, because it runs fewer cycles.
“If customers felt the heat pump was running a bit cool, we would simply set the switch-over temperature higher; it brings up the heat coming out of the registers.”
In his region, Heitz sees custom and semi-custom builders adopting hybrid heating for their clients. The payback is pretty clear, though it depends on a home’s insulation and exposure. “It costs about $38 to produce the equivalent of a million BTUs with an electric heat pump if the temperature is 20 degrees outside, and a typical house here will go through 10 million BTUs a month,” he says. “But if I go to a propane furnace at today’s prices, the cost is about two-thirds the cost of electric. People are very satisfied with the hybrids because the switchover is automatic. We set a switchover point above the place where the electric resistance heat comes on, and there is no extra maintenance, except for filter changes.”
These synergistic systems can also reduce carbon output. In areas that depend on coal for power, electric resistance backup heat creates higher CO2 emissions compared with hybrid systems. A homeowner in the Midwest can offset the CO2 emissions from a single car for an entire year by using a high-efficiency hybrid furnace instead of an air source heat pump only. A heat pump can be downsized too, if a propane furnace is handling the more extreme heating loads.
“I can tell you we’ve had zero complaints, and we have had periods where we put in large numbers of them,” says Scott Pearson, sales manager at Standard Heating, Minneapolis, a York dealer. “If customers felt the heat pump was running a bit cool, we would simply set the switch-over temperature higher; it brings up the heat coming out of the registers.”
Keep an eye out for tax credits or rebates to make a hybrid system an even better deal. Because hybrid heating systems reduce peak electrical demand at the coldest times, some electric utilities offer incentives to customers that have them installed. Check with your local utility and visit dsireusa.org for the latest incentives.