Zone Systems 101

zoneWhen zone damper systems are applied, installed and used correctly, they’re amazing.

Now, if only they were always applied, installed, and used correctly….

Let’s look at some zoning misconceptions first:
• Many people think that zoning systems can compensate for, or correct, existing air distribution system (engineer speak for ductwork) issues. Wrong. Applying zoning to a system with existing problems will only make things worse.
• Some people think zoning can be applied to any building. Wrong again. Many building and homes cannot be successfully zoned because they cannot prevent temperature cross-contamination. Examples would be systems with one central return, or rooms without doors.
• End users often believe they can have one zone set at 68 degrees, and another set at 80 degrees. Not likely.
Now let’s look at what zoning can do:
• Zoning can lower energy costs by allowing the temperature to “drift” in unoccupied areas.
• Zoning can allow for subtle differences in temperature between zones.
• Zoning can increase comfort levels by applying the correct amount of conditioned air for the zones needs.
In this article we compiled some helpful information to help you recognize installation pitfalls, and to help you troubleshoot problems with existing systems.
Common zoning problems; perceived and real.
When you think of zoning problems your mind conjures up comfort issues like over conditioning, or maybe air noise. Many technicians don’t realize that damper system issues almost always cause heating and cooling equipment problems also. These collateral problems can range from relatively minor issues like frozen coils and tripped high limits, to big dollar repairs like failed ECM motors, cracked heat exchangers, and scrambled compressors.
Now, if I ask you to list the most common causes of zoning system problems you would likely say: failed thermostats, zone control panels, or maybe damper actuators. If those were your answers, you were wrong. If you said the most common cause of zoning system problems is how the system is designed and applied, you are right. Ok, stop patting yourself on the back and read on…
Considerations that need to be addressed
1) Building layout
2) Number of zones
3) Room Grouping
4) Zone size
5) Duct size
6) Bypass or dump damper selection
7) Bypass damper location
8) Equipment selection
Skip any one of these design considerations and you’re in trouble. Don’t let anyone tell you any of these is unimportant.

Patrick is Zen HVAC’s diagnostic and training guy. Patrick started in the trade the day he left technical school and never looked back. He's served in various technical and training roles in the HVAC industry but specializes in system troubleshooting and diagnostics, retro commissioning, and technical training. His moto: If I can understand it, anybody can. Patrick uses the Zen common sense approach to teach Patrick’s Likes- His Wife, kids and dog. Old pickup trucks. Hiking. The industrial Revolution. Patrick’s Dislikes- Taking work too seriously. Anything unintuitive. Emoticons :( Patrick’s Favorite famous person- Theodore Roosevelt “I am only an average man, But I work harder at it than the average man" Famous Patrick Quote- “Well, that was stupid of me”

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