What to Consider When Upgrading to a High-efficiency Furnace

Making the switch to a high-efficiency furnace can improve your home's energy efficiency and overall comfort, but only if it goes off without a hitch. To make sure it does, it's important to consider the following issues that could pop up as you upgrade to a newer and more energy efficient furnace. Addressing these issues could mean the difference between a smooth upgrade and one that turns into a time-consuming and frustrating experience.

Size Matters

Most people tend not to think about the size of their heating and cooling systems, but making sure your high-efficiency furnace is the right size for your home is absolutely paramount. Having an improperly sized furnace could not only result in poor heating performance and energy efficiency, but it could also create an uncomfortable environment for you and others in your home.

The best way to avoid purchasing and oversized or undersized furnace is to have your HVAC contractor perform a load calculation prior to purchase and installation. By using the ACCA's Manual J and Manual S HVAC design procedures, your HVAC technician can help you choose the right high-efficiency furnace that's perfectly suited for your home's needs.

Your Existing Chimney

High-efficiency furnaces earn their namesake by extracting as much heat from exhaust gases as possible. As a result, exhaust temperatures are typically cooler than that of a conventional furnace. Cooler exhaust temperatures also mean you won't have to rely on a chimney to vent gases out of your home. In most cases, you can use PVC pipe to route gases through the roof and into the atmosphere.

This gives you an option of closing up your chimney for good or repurposing it for your high-efficiency furnace. If you choose the latter option, it's important to have your chimney re-sized in order to prevent backdrafting and other air imbalance issues. The extra airflow caused by an unmodified furnace chimney could have negative impact on your new furnace's overall performance and efficiency.

If you decide to forgo using your chimney and run both intake and exhaust pipes out the side of your home, make sure the exits for both pipes aren't located too close to the ground. Pipes blocked by snow, ice or debris could create a dangerous and potentially life-threatening case of carbon monoxide buildup in your home. Also, make sure the intake and exhaust pipes are located next to each other to prevent potential problems caused by differences in wind pressure.

Avoiding Condensation Problems

As your high-efficiency furnace extracts heat using its secondary heat exchanger, it can also cause water vapor in the exhaust to condense back into liquid form. Intermingled with other combustion byproducts, this condensation can sometimes prove acidic, causing damage to unprotected surfaces.

Drainage is the key to preventing most issues involving furnace condensate. To allow condensate to drain into the condensate trap and pump, the furnace exhaust vent pipe must be pitched back towards the furnace at least 1/4-inch for each foot of horizontal travel. It's also important for high-efficiency furnaces to have two drainage connections - one that directs water out of the vent pipe and into the trap and another that carries water from the secondary heat exchanger to the trap.

If you plan on using your current chimney, you should have a new liner installed to prevent acidic condensation droplets from damaging the surrounding masonry. If you live in a cold climate where freezing temperatures are the norm, you may want to utilize PVC pipe instead of repurposing your chimney, as the freeze/thaw cycle could damage the masonry.

Keep these considerations in mind as you upgrade your current furnace to an energy-saving high-efficiency model. For more information or assistance, contact companies like Quality HomEnergy.