What is a Modulating Gas Furnace?

Modulating Gas FurnaceIn the Ottawa Valley, it is often said that if you don’t like the weather, just wait 10 minutes. Ottawa winters vary a lot and with these changing conditions, heating requirement for your home changes too. Furnaces need to cycle on and off depending on the heating needs of the home. This on and off cycling causes wear and tear on the furnace as well as wasting energy. A Modulating Furnaces has a much wider range of heat output than a 2-stage or single capacity furnace. A typical Modulating Gas Furnace varies the heat output by up to 65%. rather than the either/or heat output of a 2-stage Gas Furnace or the on/off of a single stage Gas Furnace, a Modulating Gas Furnace uses the gas valve to make small adjustments to heat output of as little as 1% as required.

Modulating Gas Furnace Function

Variable Speed ECM Blower MotorThe Gas Valve in a Modulating Gas Furnace uses as little gas as required by making small adjustments in the heat output, using only as much gas as is required to maintain the temperature in the home. The Variable Speed ECM Blower enhances this further by adjusting the air flow to match the heating, ensuring that you feel the maximum comfort. The result is a dramatic reduction in temperature fluctuations from your thermostat set point, as well as a more even heat throughout the home. Modulating Furnaces operate very quietly, with efficiencies that can exceed 98% AFUE. In addition, the Variable Speed ECM blower uses a fraction of the electricity required by a typical furnace blower.


Modulating Gas Furnaces are available in sizes to suit any home. They are sized for the maximum anticipated heat requirements, with a little wiggle room for those days that are much colder than the norm. A Modulating Gas Furnace will vary heat capacity from as low as 35% of its full capacity, and will adjust heating in increments as low as 1% to maintain proper temperatures in your home. Modulating Gas Furnaces will rarely run at top capacity, but will operate much as a cruise control in your car. As a result, a Modulating Gas Furnace will cycle on and off much less frequently, but simply varies as required. The result is extremely quiet operation with a superior level of home comfort at the highest level of efficiency possible.


Modulating Gas Furnaces typically require a specialized thermostat to operate as their peak efficiency. These thermostats control the modulation rates as well as additional features such as humidity control and ventilation. Many are Wi-Fi Connected for remote operation. You can add a variety of accessories to a Modulating Gas Furnace. The more consistent operation of a Modulating Gas Furnace will optimize and improve the function of devices such as humidifiers, air cleaners and Heat Recovery Ventilators. Modulating Gas Furnaces cost more than less complex furnaces, but provide a superior level of comfort while using the least amount of energy possible.

Hassle Free

A Modulating Gas Furnace will last a longer that its single or 2-stage counterpart, due to the infrequent on/off cycles and rarely operating at full capacity. Ten Year parts warranties are common, with the heat exchangers typically warrantied for the life of the original owner. Modulating Gas Furnaces make much less noise than older furnaces or even new basic furnaces. The operation of a Modulating Gas Furnace is as simple as a standard furnace, but with a much higher level of comfort and efficiency.


As with any heating system, the ducts need to be properly sized so that they move air efficiently. They are however much more forgive of ductwork that is not ideal. The more consistent heat delivery and the automatic adjustment of the variable speed blower are particularly beneficial in duct systems that present challenges.

Ottawa Air Conditioner Information – How Air Conditioners Work

Air Conditioning – It’s not the heat… It’s the humidity…

A cool and comfortable home depends on precise control of humidity as well as temperature, and only a properly designed and installed air conditioning system can achieve this.

How Air Conditioners Work

Ottawa Air Conditioning system information

Air conditioners work by transferring the heat from the space they service to another, while also removing humidity. An air conditioner works very much like a refrigerator using the process of refrigeration to provide cooling for space or an entire home.

There are several types of cooling units, but in Ottawa, the most common way to cool a home is by using a mechanical air conditioner which incorporates a compressor, coils and refrigerants. Various configurations include window units,Central Air Conditioners, packaged air conditioners, packaged terminal or incremental air conditioners similar to what you would see in a hotel, and Ductless Air Conditioners.

Portable Air Conditioners are also available. Many of these also work as Heat Pumps. .
Air conditioners use refrigerant that is pumped through indoor and outdoor coils where the refrigerant pressures are varied causing it to condense and evaporate so it can can either absorb heat or get dispel heat. The air conditioning process requires some primary components for it to work effectively, and each of these components will have a bearing on the overall effectiveness and efficiency of the air conditioning system.

Air Conditioner Compressors

Air conditioners use several different types of compressors, including scroll compressors, reciprocating compressors, rotary compressors, screw compressors, and centrifugal compressors. different compressors are better suited for various applications, but residential air conditioners in Ottawa typically use scroll compressors or rotary type compressors.

Ottawa Air Conditioner CompressorThe compressor is similar to a pump which pumps cool refrigerant vapor from the air conditioner evaporator coil, then compresses the vapor to hot gas at high pressure. This high temperature vapor is pumped to the air conditioner condenser coils.

The  air conditioner condenser coils receive the hot vapor from the compressor and discharge the heat, which cools the refrigerant causing it to condense into a liquid by removing the heat that was absorbed by the refrigerant from the evaporator coils.

Air Conditioner – Metering Devices

Ottawa Air Conditioner Metering Device

In order to ensure the condensing and evaporation is done in the most efficient manner possible, the refrigerant flow must be metered as it flows through the system. Most air conditioners in Ottawa today use devices call thermostatic expansion valves (TXV). As the liquid refrigerant leaves the air conditioner condenser it is pumped to the metering device located at the inlet of the evaporator coil. The metering device restricts the refrigerant flow, allowing only the right amount to flow through it. With a TXV, the amount of refrigerant flow is based on the actual work, or energy required to cool the home. Previously, capillaries tubes and orifices were used according to the capacity of the air conditioning system, not the actual cooling required. A TXV provides for a significant improvement in efficiency.

Air Conditioner Evaporator Coils

Ottawa Air Conditioner - Evaporator Coil

In an air conditioner system, the evaporator coils  function is to absorbing heat. As air passes over the evaporator coils a heat exchange process takes place between the air and the refrigerant.  While traveling through the tubes in the coil, the refrigerant evaporates, absorbing the heat from the air being pushed across the coils. The air conditioner evaporator coil conditions the air in two ways. The temperature of the evaporators coil is below the dew point. of the air, meaning it will caused moisture, or humidity, in the air to condense into water.  The process results in sensible cooling as well as latent heat removal. The latent heat removal is part of the process of drawing moisture out of the air, while the sensible cooling is dropping the actual temperature of the air. So, it really is the humidity, not the heat. On a hot and humid summer day, both types of heat removal are required to make you more comfortable.

All the air conditioner components, properly matched and operating together are necessary to make any air conditioner system work. It is critical that they be engineered and matched as a system. When looking to buy an air conditioner in Ottawa, be sure to inquire about all the components and how the air conditioning contractor intends to match up the system.

Resources are available from AHRI (Air-Conditioning, Heating, and Refrigeration Institute), who independently test and rate the efficiency of air conditioners with specific coils and air handler or furnace combinations. Most available air conditioning rebates rely on the AHRI certification numbers for the specific combinations of air conditioning and heating equipment to verify that the actual operating efficiency of the system complies with the rebate requirements.

To learn more about  Air Conditioning for your home in Ottawa, Kanata or Orleans, why not contact Below Zero Heating & Air Conditioning Today!

Air Conditioning – Care & Maintenance


Common Air Conditioning Maintenance Issues

Important Maintenance of Evaporator Coils

Air Conditioning Evaporator Coils Act Like Filters Too!

The most common problems with air conditioners are a result of Dirty Evaporator Coils. These are usually out of sight, in your duct-work, so are often overlooked as an air conditioner maintenance item.  Symptoms of a dirty Evaporator Coil are often mistaken for low or improper refrigerant levels, but dirty coils can also be a source of mould and mildew when not proper air conditioning maintenance is overlooked. The outdoor Condensing Coils are often more visible, and in is an easy air conditioner maintenance item. These can be cleaned using a simple garden hose in most cases. Many factors can contribute to your system operating less efficiently than it should. An inefficient system means higher energy bills. These can result in the compressor working harder than it should, reducing the life span of your Air Conditioner or Heat Pump.

Proper Air Conditioner Maintenance

Dirty Furnace Filters - Important Air Conditioner Maintenance

Does Your Filter Look Like This?

With proper air conditioner maintenance, most air conditioners or heat pumps should last about 15 years. Higher quality, properly installed units can last much longer. You can follow a few simple air conditioner maintenance  steps to ensure you benefit from the longest life span, and keep your system operating:

  • Check all hose connections for leaks, and make sure the condensate drain tube is draining freely.
  • Ensure your filters are clean. A better quality air filter is best, and the frequency of required filter changes will vary.
  • Air Conditioner Too Close

    Many Air Conditioners are installed too close to the house, blocking air flow

    Ensure the outdoor Condensing Unit is clear of obstructions. a good rule of thumb is to keep things like plants and shrubbery at least 2 ft. away to ensure adequate airflow. An Air Conditioner, improperly installed too close to the house, can be a big problem too.

  • Dirt and dandy lion fluff, among other things, will buildup on the outdoor Condensing Unit Coils. This can be cleaned using a garden hose. if this is not freely visible, due to protective louvers, make a point of checking it periodically. this can normally still be cleaned by spraying water through the louvers.
  • Keep furniture and drapes away from registers.
Professional Air Conditioner Maintenance in Ottawa, Ontario

Other important air conditioner maintenance measures are best handled by a professional. Even if there is no obvious issue, you should consider having a professional inspection done once a year to identify early signs of trouble and keep your system is running as efficiently as possible.

Below Zero Heating and Cooling, in Ottawa, Ontario, offers air conditioner maintenance packages that can do this for you automatically. With an annual maintenance plan, there is no need for you to remember. Simply contact us to set up a plan and we will call you when your air conditioner maintenance is due.

ECM Variable Speed DC Blower Motors


ECM Variable Speed Motor

ECM motor, DC motor, variable speed motor, electrically efficient motor – all different names for similar types of the furnace motor. The main feature is the High energy efficiency, relative to conventional blower motors. But there are other significant benefits to consider.

The two main types are Constant Torque, often referred to as “electrically efficient”, or sometimes known as X13. Although very efficient in relation to conventional fan motors, X13 motors are about half as efficient as ECM Variable speed motors and are less capable of maintaining precision air flow.

ECM,  Variable Speed are fully variable and can be programmed to maintain constant air volumes, even in the most challenging duct systems. Rather than setting a speed, the motor is set to deliver the volume of air required for the utmost in system efficiency. The result is improved air flow and home comfort.

An added benefit to this technology is extraordinary reliability due to the brush less design and cool operation.

An ECM DC blower motor is an important and beneficial feature to consider when shopping for your next heating system.