Two-Stage Gas Furnaces - Tips for Buyers - How a Gas Furnaces WorksTwo-Stage Gas Furnaces - Tips for Buyers - Two-stage gas furnaces make up over 30% of all gas furnaces installed in residences in the USA. Two-Stage gas furnaces are more efficient than single-stage gas furnaces in most cases. When purchasing furnaces always check the ARI website for and efficiency ratings and comparisons.

Two-Stage Gas Furnaces | Higher Efficiency Furnaces - How It Works

The two-stage gas furnace runs at two different levels. A low fire and a high fire rate. The low fire runs at low demand. The high fire rate runs when there is a bigger demand. High fire or the second stage is 100% and usually, only kicks in when the temperatures are really cold outside. When the temperatures are milder outside the furnace runs at low fire. Therefore it uses less gas and in theory less electricity.

Two-Stage Gas Furnaces - Tips for Buyers - The Payoff

Saving electricity depends on the type of blower motor in the Two-stage furnace. A PSC blower motor will consume more energy than an ECM blower motor. It is best if you are purchasing a gas furnace, to purchase the furnace with the ECM motor. That is rather than the PSC blower motor. The payoff with an ECM motor is in electrical use. However, down the road, if the blower fails it will cost more for the repair. ECM motors are more expensive than PSC motors.

Two-Stage Gas Furnaces - Tips for Buyers - Blower Motor Factors | Advantages and Disadvantages

The PSC motor is a standard motor that has two or more windings inside of it. One for low speed and one for high speed. The low speed is used when the furnace is in low fire. The high speed is used when the furnace is in high fire. The PSC motor also uses a run capacitor. The ECM blower motor is variable speed and is electronically controlled. A control board causes it to work at one speed or another depending on the firing rate. Nearly the same as the PSC motor except the controls are simpler for the PSC. When choosing a two-stage gas furnace and you have a choice between the two different types of blower motors which do you choose?  The simpler less efficient PSC blower motor or the more complex, more efficient ECM blower motor?

The consideration here is repair costs when something happens. Since the ECM motor relies on an electronic control board it will be more expensive to repair if something goes wrong with the board. Whereas the PSC motor, typically relies on a simple relay for control and relays are cheap. These are factors you need to consider when purchasing one or the other. The biggest problem I have seen with ECM motors are power quality issues. If you live in an area that is susceptible to power surges and outages then you will likely want the PSC motor over the ECM motor. Either that or purchase and install a power filter to ensure no problems like surges and outages have a negative effect on the electronics.

Two-Stage Gas Furnaces - Tips for Buyers - Efficiency Testing

The two-stage furnace had a little controversy to it when they first entered the market as there was no official test for the furnace except the single stage furnace test. The NIS or National Institute for Standards made hay out of it and ASHRAE made official tests for the 2-stage furnace that are now used by ARI. ARI (formerly AHRI)  is the official testing agency that certifies efficiency ratings for HVAC equipment. All 2-stage furnaces on the market now are certified using the new test so efficiency ratings are accurate.

Buying a two-stage gas furnace is a big decision because usually, the cost of this new furnace is higher than a single gas furnace. When considering the purchase of any new furnace you have to take into account the future cost of fuel which rarely goes down. So you have to consider your budget for buying a new furnace versus the future cost of operating the gas furnace you are purchasing.

Two-Stage Gas Furnaces

Another consideration to have when purchasing higher efficiency furnaces is the resale value of the home. The more efficient the house the more attractive the house is for a potential buyer. Always remember the big variables when replacing any HVAC equipment. Good luck. 2-Stage Gas Furnaces - Tips for Buyers - See our reviews for 2 stage gas furnace reviews.

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Two-Stage Gas Furnaces - Tips for Buyers

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