The Importance of Proper HVAC System Sizing

Did you know that central air condition units and furnaces come in different sizes? Sizing both of these HVAC system components is critical for properly functioning heating and cooling. Oversized HVAC units make it difficult to maintain indoor air comfort, lead to higher energy costs, and shorten the lifespan of the equipment parts due to something called short cycling.

Think of HVAC sizing like the Three Bears—this one’s too big, this one’s too small, this one’s just right.

HVAC sizing specifics
At Bloomfield Cooling, Heating & Electric, we get it right by performing a design load calculation for new installations or for existing systems that are not performing as expected. This heating and cooling load calculation is based on:

• Precise measurement of your home room by room
• The home’s layout and construction
• The number and size of your windows (for heat gain)
• The orientation of the house
• Your landscaping (which can provide shade and keep the house cooler)
• The insulation’s R-value (a measure of its insulating effectiveness)
• Number of occupants may also be a factor

Load vs. capacity
The heating and cooling load is a measure of how much heating or cooling the home needs based on the factors noted above. Capacity reflects the amount of heating or cooling the HVAC unit can deliver (output). Therefore, an accurate load calculation is crucial, so the HVAC contractor knows how much a system must operate to deliver proper year-round indoor air comfort, and install the correct-sized equipment.

Another load to consider when sizing HVAC equipment is the part load. Since the temperatures outside fluctuate widely (especially in northern New Jersey where we operate), a house spends a large part of the day outside of the temperature zone or conditions calculated into the design load.

For example, the biting 20-degree morning could become a sunny 45-degree afternoon in the winter, or the breezy 70-degree morning can turn into a humid 95-degree day in the summer. And as we know in NJ, it’s not unusual to experience wild fluctuations in weather conditions within one week, feeling like winter on Monday and summer by Friday. This part load must be factored into the calculations to ensure the home’s heating and cooling equipment is sized to meet these variables as well.

Evaluating all these factors helps us determine the capacity and output needed for your home’s specific HVAC system (furnace, air conditioner and heat pump).

Benefits of a properly sized HVAC system
Right-sized HVAC systems use less energy and run more efficiently. Indoor air comfort is stable and your system lives out its expected lifespan with fewer service calls needed. When the system is not properly sized, you run into big problems:

• Oversized air conditioner – An air conditioner that’s too large does not run long enough to remove moisture out of your indoor air, leaving you with a house that feels muggy even though the temperature is cool. So, high indoor humidity is one sign of an improperly sized central air conditioning unit. The reason behind this is that the oversized unit cycles on and off too quickly (short cycling), causing poor air circulation . . . and leaving you with stale, humid air inside.
• Oversized furnace – If the furnace is oversized, your heating system blasts warm air quickly to meet your thermostat’s setting, but doesn’t do so effectively. This is inefficient—again, resulting in short cycling for heat that does not yield the stable warmth you seek.
• Undersized AC – Units that are too small must run constantly to meet the set temperatures. Just as with short cycling, undersized systems increase energy bills and do not perform well in terms of indoor comfort.
• Beware of repair costs – The parts in overworked systems wear out sooner than their expected lifespan, driving up HVAC repair costs and causing homeowners to deal with system breakdowns—or system replacements—that could have been avoided if the system were sized correctly.

An HVAC system is a big investment. At Bloomfield Cooling, Heating & Electric, we make sure you get the central air conditioner, furnace or heat pump that’s the right size, so you can enjoy many years of heating and cooling with a system that meets your family’s needs properly and efficiently. Contact us if your current system is not running as it should at (973) 237-0505 or info@bloomfieldcooling.com.