By-Pass Sizing Calculator

Often with zoning systems a By-Pass is needed to relieve excess air when only a small zone or number of small zones cannot deliver the required air flow thru the HVAC System. A by-pass is often ducted back into the return air or into non-critical, common conditioned temperature areas such as entry ways, hallways, basements, etc.

Select your Maximum Total System Cubic Feet per Minute (CFM), then enter the CFM of your Smallest Zone to calculate the type of By-Pass Damper you require.

Note: If the By-Pass CFM amount is 30% or less of the Total System CFM, No By-Pass is required.



The By-Pass Damper you are looking for is SPRD08.

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The By-Pass Damper you are looking for is SPRD09.

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The By-Pass Damper you are looking for is SPRD10.

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The By-Pass Damper you are looking for is SPRD12.

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The By-Pass Damper you are looking for is SPRD14.

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The By-Pass Damper you are looking for is SPRD16.

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The By-Pass Damper you are looking for is RDM18 w/SPC.

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The By-Pass Damper you are looking for is RDM20 w/SPC.

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The By-Pass Damper you are looking for is ZDSM2020 w/SPC.

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The By-Pass Damper you are looking for is ZDSM2420 w/SPC.

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The By-Pass Damper you are looking for is ZDSM3024 w/SPC.

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What is Zoning?Zoning - Precise Temperature Control, Convenience & Energy Savings for Both Residential & Commercial Applications

Zoning allows homes or offices to be divided into separate temperature zones, in essence room to room temperature control. Zoning is capable of providing this by putting a thermostat in each room or (zone). The thermostat then signals an automatic air control damper in the duct for that room or zone which controls the flow of the conditioned (heated or cooled) air. With zoning, only the area(s) needing conditioned air get it, while areas that are already comfortable do not. This solves the problems of rooms becoming too hot or too cold.

ZONEFIRST’s products can be used with any forced air heating and cooling system to improve the overall comfort, increase the energy efficiency of the HVAC System and provide added convenience of a thermostat in each room or zone.


Watch a video to see how Zoning works!

Zoning Energy Savings

When 55% of your energy bill is for Heating and Cooling, you sure don’t want to waste it in rooms that are not being used or already warm or cool enough. Add a ZONEFIRST Zoning System to reduce HVAC Energy Consumption as much as 30%!

ZoneFirst Home

A ZONEFIRST Zoning System along with a central forced air HVAC System creates the ultimate experience in terms of COMFORT, ENERGY SAVINGS AND CONVENIENCE. Allowing you to live in and raise your family in a healthy, clean environment with other features such as air cleaning, humidification, de-humidification and ventilation.

New home installation is typically less expensive than the cost of retrofitting existing homes. Charges would vary based on the accessibility for running thermostat wires and designing the duct system for zoning; existing systems may need duct modifications to accommodate zoning. The costs would further be determined by the type of HVAC equipment (furnace/air conditioner vs. heat pump), type of thermostat (setback vs. non-setback), etc.

Installation of a ZONEFIRST Zoning System provides substantial savings over installing an additional HVAC or “split” air-conditioning system. Additionally, one unit compared to two saves money in operating costs and energy. Maintenance costs are also decreased when comparing the expense of replacing dampers to the inevitable replacement of a furnace or air conditioning unit every 10-15 years.