If your old furnace is on the way out and you want to find a new furnace with a solid balance of initial affordability and long-term efficiency, buy a two-stage furnace.
Two-stage furnaces are far superior to their single-stage counterparts, and slightly less efficient than modulating furnaces. But most families don’t need the incrementally better efficiency offered by modulating furnaces because the price difference between modulating and two-stage is so great.
That’s a lot of jargon, isn’t it? Let us clear this up.
What are these stages?
Older furnaces usually have two settings – on and off. Burning fuel to produce heat or waiting to burn fuel to produce heat.
Two-stage furnaces operate at two levels, for example:
- 100% when the temperature outside drops below -35.
- 60% on most winter days when the temperature hovers around -15 or -20.
Your two-stage furnace may also start operating at 100%, but drop to 60% to maintain the temperature.
The lower setting is important because it reduces the cold swings in your house and consumes less fuel. It’s the setting your furnace will run at most of the time. The furnace doesn’t blast out a load of hot air, let the house cool, blast hot air, etc… It gets the house to the temperature you want and maintains that temperature through gentle, consistent heating
How does the furnace know when you use full blast vs, the smaller flame?
Your thermostat is smarter than it gets credit for.
The computer in the thermostat communicates the required setting to the furnace based on some nifty programming, and the furnace responds with the appropriate fuel burn.
Your thermostat accounts for the temperature outside, inside, and the current fuel consumption of the furnace.
But how does that actually save energy?
Think about it like your car.
If you want to go really fast, like 100% fast, you put your foot to the floor and burn through fuel like crazy. You’ll go fast, but you will have to stop for gas sooner than you would if you only held the pedal down 60% of the way.
If your furnace burns fuel at a rate of 60% to maintain the temperature in your house, you save money. A single-stage furnace will burn much more fuel to achieve the same result.
And there’s another bonus!
A two-stage furnace filters your air better.
It runs more often, circulates air through the filter more often and removes more harmful air pollutants that build up inside through the winter.
Stagnant air has the opportunity to collect and concentrate pollutants, while moving air has the opposite effect.
When you learn most indoor air is more dangerous to your family’s health than the air outside, you start to appreciate the value of good air movement and filtration from your furnace.
So is a two-stage furnace right for your family? It will:
- Save on your energy expenses.
- Heat your home more completely, eliminating cold spots and,
- Filter your air better.
It will do all of this for a lower price than a modulating furnace.
If price is a consideration, two-stage is a great balance between cost and function. Two-stage furnaces are quick to install and will last 15+ years with proper maintenance.