Mythbusters: The Bigger the HVAC System, the Better

While variable-capacity HVAC technology was introduced to the U.S. over 30 years ago and is very common abroad, many consumers in the U.S. are still unfamiliar with heat pump technology and are still untrusting of its capabilities. With that mindset, there are a lot of “myths” about these systems that we’re setting out to debunk!

Myth: The Bigger the HVAC System, the Better

The Truth:

Bigger does not always mean better, especially with HVAC systems. When it comes to specifying a mechanical system for a home, a system that’s too large (in both capacity and footprint) can lead to a lot of headaches, discomfort and undue burden on your wallet, as well as a shortened lifespan for your system!

You may be thinking, “How can this be? Wouldn’t a larger HVAC system just heat and cool my house better and faster? What’s so bad about that?” Trust us, you aren’t alone in that thought, but the phrase “bigger and better” doesn’t apply here.

On-Off Cycling

First, let’s cover the basics of “oversized capacity.” Capacity is the amount of heating and cooling a system provides. The “load” is the amount of heating and cooling a space needs to be comfortable. To condition your home, your HVAC system turns on full-blast then runs until it reaches your set point or preferred temperature. An oversized system might warm up your home in minutes but it’ll shut off as soon as your desired temperature is reached. Then, once the temperatures start to drop because the system is no longer running, it starts up again. This cycle is called short-cycling, and it can really put wear and tear on your system. Starting and stopping is energy-intensive, so short cycling is also wasteful when it comes to energy consumption and utility bills. Additionally, the constant on/off cycling can cause uncomfortable drafts

Performing a heat load calculation and sizing the system correctly for the space is always the best practice. Using variable speed HVAC system is also a great way to combat oversizing.  Instead of cycling on and off frequently, the compressors run constantly and ramp up or down based on the need. For even greater efficiency, a zone-by-zone control system means units can be shut off in certain rooms or areas of the home that are used infrequently. This increased efficiency means cost savings for you.

Whether conventional or variable-capacity, a system with too large of a capacity will heat or cool more powerfully than is necessary and cause short cycling. A variable-capacity system still has a range. You’re going to have performance issues if your heat pump’s lowest capacity is still too much for a space’s load. To get the best from Zoned Comfort Solutions, Beco air and heat will make sure you get a correctly-sized system.

Big Performance from Small Footprints

While your HVAC contractor makes the calls when it comes to capacity sizing, the “bigger is better” misconception among homeowners and a lot of contractors create nightmare situations for the homeowner. Always ask for a heat load calculation when installing a new HVAC system.