Blog

What is the Big Problem With Tiny Zones?

A common question our tech support team receives is, “How many zones can an Arzel panel handle?” In many cases, we have to ask, “How small of a zone do you want to create?” or “How much air do you want to stuff down that duct?”

The Problem:

We define “tiny zones” or “microzones” as any zone with a design airflow of less than 20% of the total system. If the HVAC equipment is staged in a way that we can slow the blower and reduce capacity, we go a little further. Tiny zones are problematic if we have a fixed amount of air that we have to try and push into a much smaller part of ductwork.

The effect of attempting to push ten pounds of air into one pound of ductwork can create several problems:

  1. There’s potential for objectionable air noise
  2. In an attempt to satisfy the small zone too quickly, the temperature overshoots and/or humidity will build-up
  3. Air can become too warm from heating or too cold from cooling because we are moving less air across the heat transfer surfaces

Solutions:

The solution to high static pressure caused by smaller zones is a bypass. By definition, bypass puts conditioned air back into the return, potentially making the temperature problem worse.

Some alternative relief strategies are blow-by into the big zone or leaving a run open somewhere. Another option is Slave Zones because they open and close dampers but cannot call the equipment. The use of slave zones will enable you to create a zone as small as you want without major airflow repercussions.

When designing a zoning system with a homeowner, proceed with caution if your customer wants to subdivide the system to less than 15% to 20% of the total. Take a look at the whole system and make sure you have a plan for dealing with that extra airflow. When in doubt, you can always call the zoning manufacturer for design help. Here at Arzel, you can talk with our tech support specialists and they will help you identify potential problems and solutions that will work best for you and your customer.

Would you like to learn more about proper zone sizing and system adjustments? CLICK HERE to sign up for a virtual comfort college course and learn how to better determine the number of zones a building needs, avoid tiny zones and micro zoning that could potentially damage the HVAC equipment.

Recent Posts
View All

1. EASY – Arzel®’s line of EzySlide dampers can typically be installed in less than 5 minutes, in 3 simple steps, making them perfect for retrofit. These dampers are available in branch sizes 4″ through 16″ and trunk sizes 8X8 through 12X28 in side and bottom-mounted configurations. The round EzySlide dampers have a sticker template […]

Remember when you were in the market for a new home, and can you recall the exhaustive process of browsing through countless realtor sites looking for the perfect match? After looking at your top choices, were you surprised by the state of the home’s HVAC equipment? Was the equipment about 15-30 years old, or still […]

The worst question is that which goes unasked. This statement certainly applies to HVAC sales, especially when offering accessory products like HVAC zoning. However, when working with your homeowner, it is essential to ask questions about their needs, not the product. It is more effective to first look into their comfort issues and then match […]

Consider this real-world math story problem: According to recent US Census data, there are about 122 million existing homes in the U.S. HVAC Zoning is only offered 24% of the time to homeowners. About 73% of homeowners have reported they experience comfort issues year-round. How many zoning opportunities are you missing each year? These numbers […]