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SmartZone Advanced: Method to reduce/eliminate pressure relief with variable speed fan systems

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We have discussed here the myths and facts about zone control and bypass.  As the debate still continues, ecojay SmartZone has yet another innovative way to reduce or possibly eliminate pressure relief (bypass, dump zone, etc) in certain circumstances.


  1. Variable/Multi speed fan (DS/BK/DH* Terminal on equipment)
    *DS/BK/DH energized = High speed fan
  2. Two (2) Zone systems only (although a 4 zone board can be used)
  3. One of the zones cannot be smaller than 30% of total airflow

This method will only allow high speed fan when BOTH zones are calling.  If only one zone is calling, low speed fan will run.  NOTE: The system, depending on duct sizes, may still require some method of pressure relief even if it is much less.  Typically, a small amount of "leakage" into the largest zone when the smallest zone is calling will accomplish what (if any) pressure relief is needed.  If using ecojay SmartZone dampers, they can be set easily to leak any amount of air necessary.

ecojay smartzone - low fan DS-BK when 1 zone calling using y2.JPG

SPECIAL NOTE: This method is VERY similar to using zone 1 thermostat for controlling DE-humidification.  For more about this see the article here.

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Always find out more by contacting us at ZoningSupply.com about your application.