In this article, we take a look at the various types of forced-air furnaces, and compare the difference between single stage, two stage, variable speed, and modulating furnaces.
Single Stage Furnaces
What is Unique About a Single-Stage Furnace?
A “stage” are the different speeds that a furnace runs. A single stage furnace is essentially ON or OFF. It’s running full-bore or not at all.
Pros
- The single biggest advantage to a single stage furnace is initial cost. It’s an older-style, less efficient piece of equipment, but if you’re on a tight budget, it might be your best option.
- A single-stage furnace would be acceptable for a smaller single-story home, like a cottage or ranch.
Cons
- The biggest drawback of a single stage furnace is they are not very energy efficient. If you’re replacing an old single stage furnace with a new one, your energy bills may not change much. They’re also not very friendly to the environment because they use so much energy.
- Another big issue with single stage furnaces: warm or cold spots in your home. Temperatures may spike and drop suddenly over time.
- Finally, single stage heating systems can be quite noisy when they switch on or off, and often during regular operation.
Optimal Type of Home for a Single Stage Furnace Installation
If you’re not planning to stay in your home for very long, you might want to consider getting the least expensive option, since you won’t be in the home long enough to enjoy the benefits of lower energy bills. A bungalow or small ranch home may be ideally suited for this type of heating equipment.
Is a Single Stage Furnace Worth the Price?
A single stage furnace may be ideal for you if you’re trying to keep the cost of the furnace under control. You really should avoid this type of furnace unless it’s the only type you can afford, but we recommend springing for a superior model, like the ones described below.
Two Stage Furnaces
What is Unique About a Two Stage Furnace?
There is a low and high setting as part of the “on” setting of a two stage (AKA “dual-stage furnace”) furnace. For the most part, the furnace will run on the low setting for a fixed period of time, at about 40% capacity. If it can’t reach the desired temperature during that time, or if there is a sudden change in temperature, the furnace will quickly kick into its higher stage, running at 100% capacity until it reaches the target temperature.
Pros
- Two stage furnaces deliver heat more consistently to your home. They also respond faster to fluctuations in the weather, resulting in less drastic temperature changes in the home. They are definitely more energy-efficient than a single stage furnace, resulting in lower utility bills.
- Two stage furnaces are designed to run more quietly. And because the furnace isn’t switching on and off frequently during the course of the day, they tend to be less noticeable. Most years, a high-efficiency furnace may be eligible for a utility company rebate or government incentive.
Cons
- Two stage furnaces, as expected, cost more than a single stage furnace for the same number of BTUs. It’s really a worthwhile investment though, because it provides more consistent heating and comfort to your family. And we’ve already discussed how they are more energy efficient.
Optimal Type of Home for a Two Stage Furnace Installation
A home with multiple levels, that tends to have hot and cold spots, or if you live in an area where you experience sudden temperatures changes, a dual-stage heating system will allow your family to feel cozier, more consistently.
Dual stage furnaces are a good option for the homeowner who has the budget for a slight upgrade from a single-stage furnace in a multi-level structure.
Is a Two Stage Furnace Worth the Price?
Depending on how long you’re planning to stay in the home, a two stage furnace will cost you slightly more. If you’re planning to stay for more than a couple of years, you’ll enjoy reduced energy bills to offset the slightly higher installation cost of a two stage furnace.
VARIABLE/MULTI STAGE FURNACES
What is Unique About a Multi Stage Furnace?
A variable speed (or multi-speed) furnace watches the temperature of your home and automatically adjusts the speed of the blower motor in small increments in response to the thermostat’s request. The increased precision provides more consistent heat over time around various spots in the home.
Pros
- A variable speed or multi speed furnace gives us a higher level efficiency because the system can run at the optimal speed to reach the thermostat’s set temperature. Energy consumption can be reduced by as much as 70%.
- The results of consistent airflow throughout the home results in a better regulated temperature and constant filtering of the air. This type of furnace is much quieter because it doesn’t abruptly stop and start.
Cons
- Installation cost of a variable speed or multi speed heating system is higher than less advanced furnaces.
Optimal Type of Home for a Variable-Speed Furnace Installation
Again, the biggest factor may be how long you plan to stay in your home, because of the initial installation cost. You definitely want to be there long enough (i.e. 5-10 years) to recoup some of your cost through lower utility bills. Many variable-speed furnaces run at an improved energy efficiency and may be ENERGY-STAR® certified, meaning you may be able to cash in on government incentives or utility company rebates.
Is a Variable/Multi-Speed Furnace Worth the Price?
Planning to stay in your home 5 more years or longer, it’s definitely worth considering the higher investment of a variable speed furnace. When properly installed and maintained, this type of furnace will improve the comfort level in your home and reduce your energy bills.
MODULATING FURNACE
What is Unique About a Modulating Furnace?
The modulating furnace contains a burner system that automatically adjusts the level of fuel burned in small increments to maintain a consistent temperature. The most technologically advanced residential furnaces have both a variable-speed blower and a modulating burner, giving the homeowner the most precise and consistent heat available.
Pros
- The most thrilling thing about a modulating furnace is the consistent temperatures throughout the home.
- Because this type of furnace can adapt to quickly changing outside temperatures in small increments, it minimizes fuel waste and has the smallest environmental impact over the other types of furnaces mentioned here.
Cons
- A modulating furnace will definitely require some time to recover from the higher installation costs, but you may not notice a large difference in energy savings over a variable-speed furnace in a short time.
- The ideal strategy is to stay in your home for five years or more to ensure you recoup your investment.
Optimal Type of Home for a Modulating Furnace Installation
Ideally, staying in your home five years or more will help you recover the installation costs (with the energy savings. Modulating furnaces may qualify for various government incentives and utility rebates, so you can recoup a bit of your initial installation costs. This type of furnace works best in larger homes with a variety of heating needs and multiple zones.
Is a Modulating Furnace Worth the Price?
This type of furnace will allow you to reach the pinnacle of consistent comfort in your home, if you’re willing to spend the extra at installation time. If you’re on a tight budget, this is definitely not worth the investment. But if you want to ensure your family’s comfort in a larger home, you’re going to stay in your home at least 5 more years, and save on energy costs, it’s worth the investment.
FINAL COMPARISON: HOW TO DECIDE WHICH TYPE I SHOULD BUY?
It’s bottom line time, to decide what type of furnace should you purchase. Following are a quick recap of the different types of residential furnaces
- Single Stage The key word here is inexpensive. If you’re only going to be in your home a short time, and your home is a small cottage or ranch, and you’re on a limited budget, this type of furnace will suffice. Otherwise, get at least a dual stage furnace.
- Two Stage This is a nice step up and worth the investment for consumers who want better performance, comfort and efficiency.
- Variable Speed and Modulating If you have a higher budget available and want markedly improved energy efficiency, quieter operation, more even heating and comfort for your family, and want to qualify for government incentives through the ENERGY STAR certified program.
Whatever you decide for a replacement furnace for your central Ohio home, be sure to get it installed by a trusted certified local HVAC contractor.
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