Copyright RetroZone inc.2012 



Flexdampers have eliminated many of the noise problems such as rattles found in older style damper systems.

Even without this section, chances are your Airzone installation would have no problems with noise.  But Retrozone's experience has shown that in special circumstances, such as residential bedrooms (during sleeping hours), even the slightest noise can cause concerns.  A thorough review of this section will help you avoid or fix most noise problems.


Different types of sound:

Airzone Component Sounds, including: Pump sounds

Solenoid sounds

Flexdamper Actuating Sounds

Air Sounds, including:

High velocity air rush at register

Register rattles

Airzone Component Sounds

Pump and solenoid sounds - Avoid any problem by NOT locating the Airzone control system around a bedroom or other noise sensitive area.  The pump only runs when the HVAC runs, so the slight pump hum is usually masked by the HVAC system.  

Flexdamper Actuating Sounds - Flexdampers can make a very slight "popping sound" (especially when new) when actuating.  While rarely a problem, these sounds are more pronounced in steel duct, especially when the Flexdamper is mounted at the register.  If you must register mount a Flexdamper in steel duct in a bedroom area, consult Retrozone for advice.

Register mounting the Flexdamper in a bedroom area may be acceptable if the home only has one occupied sleeping zone, and if the other zones are setback at night.  This is because the Flexdampers serving the bedroom areas would normally remain open and seldom actuate, thus having no potential to make unwanted sounds.

Air Sounds - High velocity air rush at register - As zones are closed down, more air will be forced out the remaining open ducts, sometimes causing increased register sound.  This concern is far more common with rigid steel duct than flexible duct.


Fortunately, this type of constant background sound is "white" noise, similar to a waterfall, and is usually not a problem.  However, should this sound be a problem, refer to Section 3 for methods of relieving static pressure.


Register Rattles  - More offensive is register rattles.  In a retrofit job, occasionally a register may rattle as air speed increases.  Remove and replace, or secure register vanes in such a way that rattles will not occur.  You might also try small high-density weather stripping between the register and the wall. 

Copyright RetroZone 2013


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