A What Furnace?
When buying a furnace, you can get presented with a lot of information, and a lot of words that seem to blend together. Your salesperson may say things like “High Efficient”, “AFUE”, “Condensing”, “ECM Motor”, “X-13 Motor”, “Modulating”, “Single Stage”, “Two Stage”, or “636 Certified”; and any combination of these can get confusing.
High Efficient and Condensing both mean the unit has an efficiency rating over 89%, a sealed combustion chamber, secondary heat exchanger and a combustion draft inducer. That efficiency rating is often called the AFUE (annual fuel utilization efficiency) and is the calculation to figure out how efficient the unit converts the fuel source into heat.
An X-13 motor provides constant torque for air flow, and is designed to stay consistent when static pressure increases. The motor is programmed by the furnace manufacturer to operate with the unit – size and capabilities. It leads to improved efficiency ratings over the standard PSC motor.
An ECM motor is a step up from the X-13 option. It is a DC (direct current) motor that uses magnets and windings to adjust operation. This is a variable speed motor that offers greater efficiency over the X-13 option. Again, the motors are programmed by the manufacturer of the furnace for furnace specific operation.
When a sales person mentions 636 certified, it is in reference to the venting. In 2007, Ontario’s gas code made all new high efficient furnace, water heater and boilers to be vented by Certified 636 venting. This replaces the old ABS venting that had been used for many years.
When referencing Single Stage, Two-Stage or Modulating, it usually is in reference to gas valves, and how it heats your home. A Single Stage furnace turns on at full capacity and switches off when set temperature is reached. This option allows for hot and cold swings to occur in heating the home.
A Two-Stage furnace is quieter in operation that a single stage unit, and it starts up in low fire. If it cannot reach the set temperature in a specific amount of time, it ramps up to high fire. This means the fan is running more, creating better air filtration, and decreases the hot/cold swings.
A modulating furnace starts in low fire, and increases in small increments until reaching the set temperature or it is running on high fire. This type of unit keeps temperatures in homes pretty consistent, but is designed to be running continuously at a low setting.