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?” Then they ask us, “What’s the problem with tiny zones?” Well, we’re glad you asked.

What’s the problem with tiny zones?

We define tiny zones or micro-zones 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.

How to reduce issues caused by tiny zones

One solution to high static pressure caused by smaller zones is a bypass. A bypass reroutes some of the conditioned air back into the return, so it won’t overload the ductwork. Bypass will relieve the static pressure concern, but it’s not ideal to put too much conditioned air back into the return. You might want an alternative solution.

Some alternative relief strategies include allowing blow-by into a bigger zone, or leaving a run open somewhere. Another option is to add a Smart Zone, our slave zone. A Smart Zone can open and close dampers but cannot call the equipment. This solution lets you create a zone as small as you want without major airflow repercussions.

With our Pro Panel zone control, you can designate any zone as a non-calling zone. So you won’t need to add a Smart Zone for applications with a tiny zone. Just set the small zone as a non-calling zone, and it will only receive airflow when another zone is also open.

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.

Contact us

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? Sign up for a free webinar and learn how to better determine the number of zones a building needs. Or watch our video on how to design a zoning system. We’ll share how to avoid tiny zones and micro-zoning that could potentially damage the HVAC equipment.