What is the Difference Between a Modulating and 2-Stage Furnace?

A modulating furnace keeps your home within one to two degrees of the temperature you set. The furnace will run more often than a single or two-stage. A two-stage furnace will turn on or off to keep your home at the right temperature while a modulating furnace will stay on to keep the temperature more consistent. It increases and decreases the flame to keep temperatures consistent.

A modulating furnace is on more often and this means it can seem noisier than a two-stage furnace. Here are a few of the differences between two-stage and modulating furnaces:

1. A modulating furnace is on more often and noisier because of it
2. A modulating furnace is more expensive
3. The modulating furnace is slightly more eco-friendly
4. Modulating furnaces have a larger SaskEnergy rebate available (ask us how to get yours today!)
5. A modulating furnace is more expensive than a 2-stage

In our opinion the modulating furnace is a nice furnace to have but likely more than your home needs. A two-stage furnace will get you a very similar output without the high price tag. Your energy savings between the two will not make up for the difference in price. Generally, the difference in the eco-friendly nature of the modulating furnace is about 1% in the annual fuel utilization (AFUE) efficiency rating.

Additional costs of a modulating furnace include the type of controller used to control the furnace. If you use a regular single or 2-stage controller or thermostat to control the modulating furnace they are no more efficient than a 2-stage and might actually be less efficient because they are not able to modulate the furnace to unlock the full potential.

Understanding Your Heat Loss and Heat Gain Calculation

There is only one way to correctly identify the size of equipment you need in your home. A heat loss and heat gain calculation. While a pro can often give you the best guess as to the size of machine you need it will never be as accurate as the loss and gain calculation.

Here are some things you need to know about heat loss and heat gain:

• It needs to be done by a specialist and can cost around $500
• Looks at everything from windows to insulation
• Uses your home age in the calculation
• Uses square footage
• It takes into consideration the direction of your home to the sun
• Looks at how far sofit overhang goes over your home

The cheaper way to calculate what loss and heat gain is to have a professional take your square footage, and the year your home was built, look at your insulation and calculate a general number for sizing.

Additional Furnace Costs

There is no way to know 100% that there will be no additional costs when your furnace is taken out and replaced.

Here are a few questions to ask your furnace specialist before accepting their quote to make sure they have accounted for important secondary factors.

Do I need to change my chimney?
A Mid-efficient furnace needs to use the chimney.

If the load is taken off the chimney, you now have a chimney that is too large. A too-large chimney means you no longer have the pressure to push the carbon monoxide out of your home and you now have to downgrade the chimney to keep your home safe

Before your furnace is completed you will have a gas inspection that will likely catch any chimney issues. The problem is this causes extra fees later.

What about potential moisture issues?
A mid-efficiency furnace uses the air in your home for combustion drawing in air from the front door of your furnace. Because the air is being drawn into the furnace directly it will help reduce the moisture level in your home.

A high-efficiency furnace will take the air for combustion directly from outside. This will keep the moisture inside your home because it’s not being drawn into the front of the furnace. In fact, the high-efficiency furnace has a sealed combustion chamber so surrounding room air has no effect on the furnace in the room.

When switching from a mid-efficiency to a high-efficiency furnace this is something you have to consider.

Is my ducting the correct size for my new furnace?
There are very few mechanical experts in Saskatchewan. Because of that ductwork can often be sized incorrectly. Your ducting may need to be properly fitted for your new furnace.

When your furnace is installed your furnace specialist must perform a temperature rise test to ensure the furnace meets the manufacturer’s installation instructions as well as to pass the required gas inspection. All manufacturers require the furnace to run inside a specific temperature scale.

If it is not within the specific scale listed on the manufacturer’s rating then the furnace can not be registered for warranty nor will it pass a gas inspection. This is because the furnace won’t last its life expectancy if it doesnt meet the manufacturer’s rating.

The life expectancy is greatly reduced when the furnace runs outside of the temperature rise zone listed on the furnace data rating plate. This temperature rise is based on the ductwork that exists inside your home and the installation quality as well.

It can be difficult to know whether it’s worth replacing your furnace or simply trying to repair it. We advise calling an HVAC specialist to give you a quote on both the repair and replacement. It may even be worth replacing your furnace for the energy efficiency you can get. There are also good rebates in Saskatchewan on furnaces from Sask Energy.

Ask Questions About Your Specific Furnace

If you want an honest opinion from a trusted expert in the Regina area give us a call at (306) 552-5489. We will provide you with all of the information and make sure you truly understand what a repair and replacement will look like in your home.