In a typical home there is either a heat pump, which can do both, or it’s a gas furnace for heat and an air conditioner for cooling. But there’s another choice that’s gaining in popularity as people learn more about energy efficiency and energy conservation.
In the Catawba Valley area, using electricity to heat a home is pretty cost effective. This is because electricity is relatively inexpensive here compared to the cost of natural gas or oil and our winters are fairly mild overall. So most people use an electric heat pump to do this. But there’s a catch. A heat pump works by pulling the warmth out of the outdoor air. Even in winter there is enough warmth outside for a heat pump to find heat – but only down to a certain temperature. Once the outdoor temperature gets too low, a heat pump needs a backup heat source. In most cases the backup heat source is a strip heater, or resistance heat, which we install inside your indoor unit as part of your system. Here’s the catch (I told you it was coming): this is a very expensive way to heat a house. Not quite as expensive as burning money in a fireplace maybe, but close.
In many cases there is another option. It’s called a Dual Fuel System or a hybrid, and it consists of a heat pump and a gas furnace. Kind of like the car version of a hybrid, a dual fuel system uses both electricity and gas. Of course it doesn’t use speed to decide which to use. It uses the outside temperature. It’s a pretty neat concept because it uses the best of both systems to heat your home more cost effectively and comfortably.
When it’s cold and your house needs heat, a sensor outside reads the outdoor temperature and sends a message back to the thermostat. If the outdoor temperature is above the “setpoint”, a specific temperature calculated by us, your favorite HVAC contractor, the thermostat knows the heat pump can do the job and will turn it on. If the temperature outside is below the setpoint, the thermostat knows the heat pump can’t keep up and it has to turn on the back up heat source. Instead of turning on the expensive strip heat though, it turns on the gas furnace. When the outdoor temperature rises above the setpoint again, the sensor sends a message to the thermostat which automatically switches back to heat pump mode.
There are other advantages to a dual fuel system and most of them have to do with comfort. If you read the section on heat pumps, you know that as the outside temperature drops, the air blowing out of your registers gets colder. This doesn’t happen with a furnace. The air coming out is warm. Really warm. Lots of people who have been around gas heat will tell you it’s a much warmer, more comfortable heat. It can also heat your home faster because of this and a couple other reasons that I won’t go into here. (They’re boring HVAC facts. If you want to know, please ask. We’ve got all kinds of details we can give you.)
But a dual fuel system doesn’t make sense for every house. One huge factor is whether natural gas is even available in your neighborhood. It can be expensive to run a gas line to your house if there isn’t one there yet. Another is the size and set up of your home. There are some other things too. Only a reputable HVAC Contractor is going to be able to tell you whether this can work in your home. If it’s something you’d like to check into or learn more about, please don’t hesitate to contact us. We’d be happy to help.