What is the Difference in a Single-Stage, Two-Stage & Variable Capacity Furnace?

Posted by Ohio Heating

Aug 29, 2019 7:41:00 AM

Do you know the differences between single-stage, two-stage and variable capacity gas furnaces?  How many stages a furnace has is determined by its gas valve type. The more stages a furnace runs on, the better temperature balance and air filtration you have in your home. furnace Bryant 22

A single-stage gas furnace has a gas valve that opens at 100% capacity. If it is a 100,000 BTU per hour furnace, it is always at the 100,000 BTU rate. These furnaces are the least expensive, are very dependable and are less costly to repair. Their biggest drawback is that they are not very energy efficient. Most have single-speed blower motors, so they blow at full speed all the time and tend to be noisier than two-stage or variable capacity equipment.

A two-stage gas furnace has valves that can open at either about 70% or 100%. This means that the 100,000 BTU furnace can operate at 70,000 BTUs per hour or at 100,000 BTUs per hour. These types are usually moderately priced, fairly dependable and repair costs are about average. Efficiency is low to high depending on the model and how often you run the equipment at 100%. This equipment runs at the low stage most of the time, which is 65% or 70% depending on the furnace model. With this equipment, there are longer cycles and fewer temperature swings of one to two degrees. Most have multi-speed or variable-speed blowers. They operate at a low speed until the furnace is hot and then speed up.

A variable capacity furnace (also called a modulating furnace) has gas valves that modulate between about 40% and 100% capacity. A modulating 100,000 BTU furnace can operate at any heating level between 40,000 and 100,000 BTUs. These furnaces are more expensive but have a very high efficiency rating. They run at the lowest capacity necessary to maintain balanced temperatures in your home. All have variable-speed blowers, which means there is rarely any cool air coming from the ducts or any change in temperature. They are also the quietest furnaces.

Which type is best for you? When choosing a new furnace for your home cost is always important. There are three ways to look at cost.

  1. Initial price: The cost of buying a gas furnace and installation
  2. Operating cost: The energy cost for running the furnace (determined by its efficiency)            3. Repair costs

In Central Ohio, a high-efficiency gas furnace can pay for itself in less than 10 years, sometimes less than five years in some cases. You need to decide whether it is worth it to pay more for the added climate control of a two-stage or modulating furnace.

Buying a new heating system for your home can be confusing. Selecting just the right options and features can be difficult. Our highly trained team at Ohio Heating & Air Conditioning can help you make the right decision.

Our sales, service and installation teams are specially-trained in the design and installation of heating systems. They can help you determine the right system for your home and your budget.

Easy Financing • Apply Online • Low Monthly Payments*

Ohio Heating financing

When an Ohio Heating & Air Conditioning technician steps into your home, you know you are getting a technician who has demonstrated exceptional levels of knowledge in HVAC.

Our Technicians are:

  1. NATE Certified
  2. Bryant Factory Authorized
  3. Licensed and Bonded
  4. Experienced on all Makes and Models

Contact Us Now!

* Subject to qualifying credit approval. Plan 3128. 84 payments. Beginning with 1st transaction, 12 month promo period with no payments required followed by 84 amortized payments based on the balance at the end of promo. Interest charged to account is waived if entire purchase balance is paid before the end of promo period. No prepayment penalty. Interest Rate stated in your loan agreement fixed for life of loan. No Interest if paid in full during the promotion period

Topics: Replacing Your Furnace, choosing a new heating system

Follow Us!​

We hope you find the information useful.  If you have any questions, please contact us.


Subscribe to Email Updates

Recent Posts