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How To Save Energy With A Right Sized HVAC System

By Your Advisor 7/7/16 9:00 AM Time to read:

When it comes to installing an HVAC system, a larger unit is not necessarily better. In fact, units that are too large for a home often come with increased installation and maintenance costs. While there is technology that currently exists to aid in accurately sizing a new HVAC system, some contractors still use casual methods of sizing. In some cases, contractors will purposely oversize a system in order to reduce the amount of call backs, allow for future home expansion, or simply because the customer demanded it. Here's a detailed explanation on why oversizing is a problem and how right sizing a system can actually save you money and reduce energy consumption.

The Problem with Oversizing

Homeowners will encounter many issues if they choose to install an oversized HVAC system. For instance, a system that is too large for a home will inevitably suffer the negative effects of short-cycling. Short-cycling occurs when an HVAC system is runs and stops at short inefficient intervals. This happens when an oversized system's capacity heats or cools a home too quickly. Increased system usage will create wear and tear on the interior components leading to a reduced system lifetime. For example, a blower with too much power will create excess duct pressure resulting in duct leakage down the road. Additionally, a system that is short-cycling will not be on long enough to perform adequate dehumidification which contributes to that muggy and clammy feeling in the home. By far the worst symptom of oversizing will be the uncomfortable temperature variations. When getting a system sized, homeowners should steer clear of any contractor that relies only on their experiene when designing the system..

The Benefits of a Load Calculation

An effective load calculation will take into account unpredictable variables which is why an appropriate size would be 10 to 15 percent larger than the "right" size. When performing a load calculation, technicians take into account many factors including:

  • Age of building
  • Intended use
  • Ventilation and insulation
  • Heat generated from lighting and machinery
  • Number of people in the building
  • Size, shape, and orientation of the home
  • Local climate

A precise load calculation ensures that an HVAC system maintains the desired temperature without having to overwork itself. A proper load calculation can also reveal potential areas of improvement in the home that may be causing excess heat loss or gain. While this is not the main purpose of the calculation, it is a helpful ancillary result.

Sizing an HVAC system takes more than an educated guess to perfect. Proper load calculation ensures that an HVAC system runs at maximum efficiency so that residents can experience ideal comfort levels and low maintenance and utility costs.