Sizing a Furnace: The Ins and Outs

If it’s been several years since your last furnace installation, you’ll discover that new furnaces are equipped with high-efficiency components that are more durable and provide greater heating performance than furnaces produced just a few years ago. Keep in mind, to get the best performance from your furnace replacement, sizing a furnace correctly is vital.

Sizing a Furnace Replacement

Sizing a furnace is a crucial element of the installation process. A furnace installation that’s oversized for the home’s heating load produces poor comfort and efficiency results. It can also result in early malfunctions and component deterioration down the road. On the other hand, furnace capacity which doesn’t meet the heating demand is going to be unable to meet your home comfort needs.

Here are some of the important questions you can expect to hear from an experienced contractor regarding sizing a furnace installation.

Do you experience hot or cold spots in any of the rooms?

  • This is an important question which helps determine airflow imbalances, heat gain and loss properties from room to room and the ability of the current furnace to supply adequate heating evenly and comfortably.

Are there any remodeled rooms or room additions?

  • Retrofitted rooms and room additions, especially in older homes, are often constructed from different building materials than the original home construction. Different materials have different heat resistance properties, and this must be accounted for during the home evaluation.

How many people live in the household? What are their ages and energy usage habits?

  • This question serves the occupants and is important for system sizing in that it helps determine temperature preferences in relation to the heating load, and the approximate amount of moisture typically present in the home from breathing, cooking, bathing and other activities of occupants.

When was your masonry chimney last inspected?

  • New furnaces produce acidic condensation in the exhaust gases and require special precautions and components for safe venting. Masonry chimneys typically shouldn’t be used for modern furnace systems for this reason. However, if the masonry chimney is in good condition, and if it’s entirely lined with clay tile, it may support the exhaust of a mid-efficiency furnace with an annual fuel utilization efficiency (AFUE) rating of 80 to 89. On the other hand, to maintain home safety and structure integrity, it’s recommended that a powered venting system constructed of appropriate materials (metal or PVC) is used to vent exhaust gases.

Have you noticed any drafts near windows and doors?

  • Air leaks around doors, windows and other wall apertures, like around pipes, flue and wiring, are quite reasons for high energy bills and poor home comfort. A little caulk and weatherstripping goes a long way to solving comfort and efficiency issues in the home’s shell. First make sure you seal the attic hatch, or you’ll be sending your energy dollars up into the rafters.

Have you performed any energy efficiency upgrades, such as adding insulation?

  • A good insulation barrier is important to obstruct heat transfer through the ceiling, floor and walls. For best results, ask your contractor to conduct a home energy evaluation. Special equipment is used to reveal issues with air leaks and inadequate or damaged insulation. Sealing up your home lowers the heating load, reducing the capacity required when sizing a furnace replacement.

Are there any rattling, clamoring or banging noises coming from the air ducts?

  • In addition to asking questions pertaining to sizing a furnace, good ductwork design is important for furnace efficiency, in regards to heating capacity, home comfort and fuel efficiency. Air ducts with debris, leaks, damage or other flaws significantly hinder free airflow, create hot and cold spots and will compromise the performance of your new furnace. Rattling, clamoring and banging noises are positive indicators of problem ductwork. Sealing and insulating the ducts or designing a new duct system along with sizing a furnace replacement may be necessary.

Everyone wants the best deal possible for major purchases, and autumn is a great time to size up your furnace options and take advantage of pre-season specials and rebates. Sizing a furnace correctly will help ensure you get the right size for the best deal and long-lasting performance./p>

If you need help selecting and sizing a furnace replacement for your home in Elmhurst, Maywood, Westchester and all surrounding areas, contact us at Riley Heating & Cooling.