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.

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SPRD08

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

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SPRD09

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

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SPRD10

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

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SPRD12

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

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SPRD14

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

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SPRD16

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

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RDM18-SPC

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

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RDM20-SPC

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

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ZDSM2020-SPC

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

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ZDSM2420-SPC

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

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ZDSM3024-SPC

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

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Warranty Information


WHEN INSTALLING ANY ZONEFIRST PRODUCT...

Read instructions carefully. Failure to follow the instructions could damage the product or cause a hazardous condition. Ensure that the installer is a trained, experienced service technician. After completing installation, use these instructions to check product operation.

LOCATION

The Zone Dampers are installed typically near the furnace/ air handler plenum and in the air duct takeoff to the zone. Always make sure the dampers are accessible for wiring, checkout, duct cleaning and replacement of damper or motor is ever needed.

HUMIDIFICATION

Do not install dampers in heating systems where spray or atomizing type humidifiers are installed in the furnace plenum or air supply duct. Excessive lime or mineral deposits accumulate on damper blades and cause improper operation. For humidification, use evaporation type humidifiers or return air type humidifiers.

INSTALLATION CONSIDERATIONS

Install Zone Dampers (ZDS) or (ZDB) into a squared air duct. Frame misalignment may jam the damper blades. Do not weld dampers to air ducts.

ZONEFIRST warrants its products to be free of defects and to provide trouble free operation for a period of five (5) years from date of installation. The warranty is limited to the cost of the product and does not include claims for labor or consequential damage. Prior authorization must be obtained from ZONEFIRST before returning and product. Products returned under warranty and found to be defective will be replaced or credited. Items returned within the warranty period that are found not to be defective and those items that are out of warranty are subject to a minimum repair or inspection fee. All returns must be sent freight prepaid with the return authorization number clearly marked on the packing slip. Returns without prior authorization will be refused. All items damaged in freight cannot be returned and a claim with the freight carrier must be made.

Returns: All returns must have prior authorization and are subject to a 20% re-stocking charge. Special order items may not be returned for credit. Returns are for credit only and can only be used towards future purchases.

View ZoneFirst's Warranty Policy