# Multiple dryer (common) venting – Maytag MDG120 User Manual

## Page 12

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**IMPORTANT: **

**For extended duct work runs, the**

**cross section area of the duct work can only be** **increased to an extent. Maximum proportional** **duct work runs **

**cannot **

**exceed twenty (20) feet**

**more than the original limitations of twenty (20)**

**feet with two (2) elbows. When the duct work** **approaches the maximum limits as noted in this**

**manual, a professional heating venting air**

**conditioning **

**(HVAC) **

**firm **

**should be **

**consulted**

**for proper venting information.**

**IMPORTANT; DO NOT **

**use screens, louvers, or**

**caps on the outside of opening of exhaust duct** **work**

**MULTIPLE DRYER (COMMON)**

**VENTING**

**If it is not feasible to provide separate exhaust**

**ducts for each dryer, ducts from individual** **dryers may be channeled into a “common main** **duct.” The individual ducts should enter the**

**bottom or side of the main duct at an angle not** **more than 45° in the direction of air flow and**

**should be **

**spaced at least **

**48-% **

**inches apart.**

**The main duct **

**should be **

**tapered, with the**

**diameter increasing before each individual 14-** **inch (minimum) duct is added.**

**IMPORTANT: **

**The MDG120 is not provided with**

**a back draft damper. When exhausted into a**

**multiple (common) exhaust line, a back draft** **damper **

**must be **

**installed at each dryer duct.**

**IMPORTANT: **

**No more than four (4) dryers**

**should be **

**connected to one main common**

**duct.**

**The main duct may be any shape or cross sectional area, so long as the minimum cross section**

**area is provided. See the **

**illustrations **

**showing**

**the minimum cross section area for multiple dryer**

**round or square venting. These figures **

**must be**

**increased 10 square inches when rectangular** **main ducting is used, and the ratio of duct width**

**to depth should not be greater than **

3

**-V**

2

** to 1.**

**These figures **

**must be **

**increased in proportion if**

**the main duct run to the last dryer to where it** **exhausts to the outdoors is unusually long (over**

**20 **

**feet) or has numerous elbows (more than two**

**[2]) in it. In calculating duct work size, the cross** **section area of a square or rectangular duct **

**must**

**be **

**increased **

**20 **

**percent for each additional **

**20**

**feet. The diameter of a round exhaust must be**

**increased **

**10 **

**percent for each additional **

**20 **

**feet.**

**Each 90° elbow is equivalent to an additional 30**

**feet and each 45° elbow is equivalent to an** **additional 15 feet.**

**MULTIPLE DRYER VENTING WITH** **14” DIAMETER (2,150 CFM) EXHAUST CONNECTIONS AT COMMON DUCT**

VtRTlCAL OUCTHa

NO. OF ORrSRS

*i*

1

HKlijHThoss

«5

380 299 119

ÄMHüH WÍW ■

DUCT DIAMETCR <KI

2<

22

te

U

MOWIZOKTAU OUCTWO

**Д18-Д.-V -**

**_l**

2X0 aSARANCE

**MQN--------- r**

I-<9 3/8’

2X0 CLEARANCE

**IMPORTANT: NO MORE THAN 4 DRYERS**

**CAN BE CONNECTED TO ONE COMMON**

**DUCT (VENT).**

**FORMULAS TO CALCULATE DUCTING CROSS**

**SECTIONAL AREA**

**CROSS SECTIONAL AREA OF A ROUND**

**DUCT = .785 **

**X **

**D2 WHERE D = DIAMETER**

**OF THE DUCT**

**o**

**CROSS SECTIONAL AREA OF A RECTANGULAR**

**DUCT = WXH WHERE W= WIDTH AND H =**

**HEIGHT **

**I**

**NOTE A: OPENING MUST BE TWO (2) INCHES**

**LARGER THAN DUCT (ALL THE WAY AROUND) THE**

**DUCT MUST BE CENTERED WITHIN THIS OPENING**

**IMPORTANT: **

**For extended duct work runs, the**

**cross section area of the duct work can only be** **increased to an extent. Maximum proportional**

**duct work runs **

**cannot **

**exceed twenty **

**(20) **

**feet**

**more than the original limitations of twenty **

**(20)**

**feet with two (2) elbows. When the duct work** **approaches the maximum limits as noted in this**

**manual, a professional HVAC firm should be** **consulted for proper venting information.**

**IMPORTANT: **

**Exhaust back pressure**

**measured by a manometer at each dryer** **exhaust duct area **

**should not **

**exceed 0.3**

**inches of water column.**

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