How to Tell If HVAC Zone Damper Is Normally Closed or Normally Open? 

There are different types of zone dampers. Some of them are normally closed, while others get closed only when power is applied.

To find out what type of dampers your zoned HVAC system has, consult the user’s manual. In case your damper is already installed, you’d have to inspect the ductwork – turn off the HVAC system and take note of the position of the damper’s blades (this is their normal state).

How to Tell If HVAC Zone Damper Is Normally Closed or Normally Open?   

There are two main types of dampers – some are normally closed, while others are normally closed. Once power is applied to the motor, it makes the damper open or close, and once the power gets removed – the spring brings the element back to its normal position.

  1. To figure out what type you have, you can simply consult the user’s manual. If you know the model of your damper, you can easily find the manual online.
  2. The more challenging way out would be to cut the power to the damper and take a look at its blades. If the spring made them close, then you have a normally shut damper and vice versa. 
  3. If you haven’t installed the dampers just yet, simply have a look at the component – this is its normal position. If the plate or the blades are open, then the damper is a ‘normally open’ one. 

Read: How To Adjust HVAC Automatic Dampers?

Are Zone Damper Normally Closed?

A zone damper can be either ‘normally open’ or ‘normally closed’. The functions and features of the different types would be the same.

Many manufacturers have their dampers available in both configurations and in various diameters. 

Is Honeywell Damper Open or Closed?

Some Honeywell dampers are spring open and power closed, which means that the components are ‘normally open’. But a lot of damper models come in two different configurations.

The Honeywell TrueZone Direct Drive damper, for example, can be either normally closed or normally open. You can easily check that in case you still have the owner’s manual. 

Read: How To Know If HVAC Zone Damper Is Bad?

How to Tell If HVAC Damper Is Open or Closed?

The easiest way to find out if your dampers are open or closed is to make your HVAC system call for heat from all zones. If the air is flowing through the registers, then the damper is open.

This will not, however, help you find out if the dampers are normally open or normally closed.

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How Do I Know If My Automatic Damper Is Open?

Ideally, you would want to perform a visual inspection, to find out if your dampers are open or closed when no power is applied

Some dampers are easily accessible, so all you would have to do is see if the plate or blades are closed or open when your HVAC system is not working.

Read: How To Locate HVAC Dampers In Ductwork?

Should HVAC Damper Be Open or Closed in Summer?

Usually, the people who live in two-story houses would be able to benefit from closed or open dampers during the different seasons.

In the summer, for example, you might want to close the downstairs dampers and open the upstairs ones. Cool air naturally sinks and having the dampers in such a position is an energy-efficient and effective way of keeping your house nice and cool.

Read: How To Troubleshoot A Honeywell Zone Damper?

Is It OK to Close HVAC Dampers?

Ideally, you would want to consult the HVAC technician who installed your system to find out if it would be okay to close off some of the dampers. If your system has a bypass duct, then closing the dampers will not lead to the build-up of static pressure.

However, if there isn’t another way for your heating and cooling equipment to get rid of the excess air, then you would have to keep the dampers slightly open at all times by adjusting the damper’s bleed rate.

How Do You Adjust a Zone Damper?

No matter whether your damper is a normally open or normally closed one, you can convert the component to be the opposite.

  1. Leave the damper in its normal position.
  2. Loosen the screw and then remove the motor.
  3. Push the grommet from its hole and push out a plastic plug from the opposite side.
  4. Change the holes for the plug and grommet.
  5. Tightly close the damper blade and place the motor on the opposite side.
  6. Tighten the screw and wire the damper.

Read: Can Zone Damper System Save You Money And Is It Really Worth It?


How Do You Identify a Damper?

In a lot of cases, you’ll be able to find the dampers close to the main trunk – right where it starts feeding the supply ducts. The exact place that houses the damper might have a metal lever or a screw.

The actual dampers typically look like a metal cylinder with a plate or blades inside. Automatic dampers also have an additional cover at the top of the cylinder with the motor.

How Do You Balance HVAC Dampers?

Air balancing basically means adjusting the heating and cooling system in such a way, so that every room in the house receives the proper amount of conditioned air (according to the homeowners’ preferences).

Adjusting your dampers to be open or closed plays a huge role in air balancing. But you might want to adjust the elements not only in accordance with how often you use a certain room but also by taking the seasons into consideration. 

How Do You Override a Damper?

If you have an automatic damper that has gone bad and that is normally closed, but you urgently need to push some conditioned air into the blocked zone, then you can attempt to disconnect the motor from the shaft and manually open the damper.

Why Is One Zone of My AC Not Working?

The dampers might be closed off, blocked, or simply dirty. Blocked air filters and dirty ducts might also be to blame.

If the thermostat responsible for a certain zone has gone bad, then the area won’t be receiving any conditioned air as well. 

How Do I Know If My Honeywell Damper Is Open?

Turn on all the HVAC zones in the house and check the airflow at the registers. If there is air flowing through the vents, then the Honeywell damper is open

How Many Dampers Is There in HVAC?

If you have a zoned HVAC system, then the chances are high that there is a damper in every supply duct.

How Do You Check Your HVAC Balance?

Air balancing is a complicated thing that, ideally, should be performed by an HVAC technician. The expert would:

  • Take initial airflow readings using a commercial balancing hood
  • Compare the readings to the design grille, register, and system airflow (they should be within 10% of the design airflow)
  • Adjust the fan to obtain the right CFM
  • Conduct final testings that include fan speed, temperature change, electrical, and total external static pressure measurements  

What Happens If There Is Not Enough Return Air?

The HVAC system will not be able to properly heat or cool your house if there is not enough return air

The return air ducts are the elements that bring the air back into the system. To be able to function correctly, they should be unobstructed and kept in good condition.