About Duel Fuel Systems

      Since it is a rare task to replace your central heating and cooling system, let's start with some basic knowledge about a typical set-up. The most common heating and cooling system set-up is a gas furnace with a coil and an electric air conditioner. This is a ‘split system', which means the coil is located inside the home with the furnace and the rest of the cooling component (the AC) is outside...hence the system is split between locations, giving its name. The air conditioner uses the furnace's blower to distribute cool air when it's hot outside. The furnace heats the home with a fossil fuel (i.e. natural gas, propane or oil) when it's cold outside. The hybrid is different from a typical system because it provides two heat sources: electric heat and a fossil fuel. In many locations, it is more economical to heat the home with the electric heat pump, at least until the outdoor temperature falls below a specific temperature point. Below that temperature point, the furnace heats the home more economically.

       A dual-fuel or "hybrid" system actually uses a heat pump with a gas furnace. The outdoor system is the heat pump, and instead of an air handler, the indoor section uses a gas furnace with a coil. The heat pump is set to heat the home until the outdoor temperature reaches a specific degree. Once below the set outdoor temperature, the system switches to gas heat.

      The contractor simply installs a compatible, programmable thermostat featuring dual fuel mode and an outdoor temperature sensor on the heat pump. The installer or homeowner can enter the “set-point” in the thermostat, which becomes the trigger temperature to change from electric to gas heat. The dealer should be able to provide the most efficient “set-point” based on the system’s capacity, efficiency and regional climate requirements. During heating season, when the outdoor temperature falls below the set temperature for the heat pump, the system will switch over to gas furnace heating.

      A hybrid combines the best of both a furnace and heat pump to heat your home cost effectively and comfortably. Here are the reasons why hybrids are economical:

1) Heat pumps can heat a home for fewer costs than a furnace above specific temperatures.

2) The furnace can heat the home for fewer costs than a heat pump below specific temperatures.

      At specific outdoor temperatures, heat pumps have a difficult time keeping up with demand and become less efficient in heating the home. Supplemental heat is required to help keep the home comfortable during those temperatures. In a traditional heat pump system, and electric heating kit is installed in the indoor section to supplement the heat. Unlike the heat pump that moves heat from outside, these supplemental options will increase electricity at a greater rate because they must create heat. This is a common set-up for markets in which the only heat source is a heat pump.

      However in markets where furnaces are the dominate heat source, and air conditioners are used to cool in the summer, hybrids make the most sense. Not only can a heat pump cool the home as efficiently as the air conditioner, they can cost effectively heat the home to specific temperature lowering the consumers total heating costs for the winter. When the outdoor temperature requires additional heat source, the heat pump will turn off, and the furnace will take over to heat the home. This is done economically by setting the thermostat to a specific outdoor temperature, which can vary per household.

       The outdoor heat pump must at least meet the government minimal efficiency standard of 13 SEER/7.7 HSPF, but you can also choose from several more efficient heat pumps that carry the ENERGY STAR rating. The gas furnace must meet the 78% AFUE energy efficiency requirements. Our heat pumps range from 13/8.0 HSPF to 20 SEER 10/HSPF, and our gas furnaces range from 80%-97.4% AFUE.

Most efficient options.

      A high-end heat pump like the iQ Drive® Heat Pump features a sensor and thermostat control that is ready for dual-fuel operation. Because of its patented controller technology, it is not only the most energy efficient air-source heat pump available; it can operate at lower set points than other air-source heat pumps nominally rated at the same capacity. Translated, a 3-ton iQ Drive Heat Pump could be set to continue to run at a lower outdoor temperature than that of a typical 3 ton Heat Pump. This system also features extraordinary dehumidification during humid summers and extremely quiet operation. It is compatible with any of our iQ Drive Ready furnace or air handler products.

Mid-efficiency options.

      Even if you are not in the market for the top-of-line dual-fuel system like the iQ Drive®, you can get a mid-efficiency system, like a 15 SEER Heat Pump with a 80 or 95.1% AFUE Furnace. Many of these systems also qualify for the Federal Tax Credit (U.S. only) which provides up to $1500 in a tax credit. Check with your local utility company to see if there are special rebates for installing high efficiency heating and cooling equipment. In the U.S., you can check out the Database of State Incentives for Renewables and Efficiencies (http://www.dsireusa.org) for information on incentives in your state.

Standard efficiency option.

      If you can only invest in the minimum-efficiency systems, they are still up to 30% more efficient than most systems installed between 1992 and 2005. A standard efficiency system is not likely to be eligible for a local rebate nor is it eligible for the federal tax credit program. However, choosing a standard efficiency dual-fuel system over the standard efficiency furnace/air conditioning system will still yield savings in operating costs.

Is there a hybrid option for a packaged system?

      Some locations use a packaged system instead of a split system. A packaged system houses the entire system (coil, blower, etc.) in one outdoor system. If you have a packaged system that heats your home through gas/electric or heat pump technology, you may want to consider our iHybrid. This all-in-one comfort system takes advantage of gas and electric heat to reduce operating costs.

A qualified contractor can help determine the right system for your home.

      The key to getting the most economy out of a hybrid is identifying the economic balance point temperature. This is the temperature in which a furnace begins heating the home for fewer costs than the heat pump. A contractor can simply calculate this using the manufacturing heat pump and furnace ratings and local utility costs. A hybrid system is unlikely to be cost effective if the economic balance point is higher than 35° F.

      If the balance point falls below 35° F, then there is a better chance a hybrid will be the choice system, but only a contractor can determine the true savings vs. investment decision. Factors such as home structure, equipment selection, local utility costs, weather and usage will all play a role in determining the final economic benefit.

      More than likely, if you already have a furnace and an air conditioner, a hybrid will have a payoff. If you have short summer seasons and reasonable fuel rates, like Alaska, then a hybrid is probably not the right choice. If you have short winters and long summers, like parts of Florida, then a heat pump system to heat the home may still remain the right system economically.

Click here for Maytag's Estimated Annual Hybrid Operating Costs