Ventilation (DHM090R4000 & DHM120R4000)
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Fresh air needed
Good air quality is based in part on the capacity of the home's ventilation system. The capacity to ventilate is measured in CFM (cubic feet per minute) or L/s (liters per second) of fresh air being distributed in the living space. If the dehumidifier is being used for ventilation, use the ASHRAE 62.2 Ventilation Standard, the Room Count Calculation Method, or the Air Change Per Hour (ACH) Method to determine your continuous ventilation needs. Next, divide the continuous ventilation need by the dehumidifier's ventilation capacity to determine the number of minutes of ventilation per hour.
DHM090 and DHM120 models have a 6" ventilation inlet. DHM065 can not control ventilation.
ASHRAE 62.2 Ventilation Standard
|
Floor area (ft²) |
Number of Bedrooms / CFM |
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0-1 |
2-3 |
4-5 |
6-7 |
>7 |
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| < 1500 | 30 | 45 | 60 | 75 | 90 |
| 1501 - 3000 | 45 | 60 | 75 | 90 | 105 |
| 3001 - 4500 | 60 | 75 | 90 | 105 | 120 |
| 4501 - 6000 | 75 | 90 | 105 | 120 | 135 |
| 6001 - 7500 | 90 | 105 | 120 | 135 | 150 |
| >7500 | 105 | 120 | 135 | 150 | 165 |
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ANSI/ASHRAE STANDARD 62.2-2010 - Ventilation Air Requirements; values in cfm |
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Room Count Calculation Method
| Living Space | Number of Rooms | x CFM (or L/s) |
= |
CFM Required |
| Master Bedroom | x 20 cfm (or 10 L/s) |
= |
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| Basement | x 20 cfm (or 10 L/s) |
= |
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| Single bedroom | x 10 cfm (or 5 L/s) | = |
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| Living Room | x 10 cfm (or 5 L/s) | = |
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| Dining Room | x 10 cfm (or 5 L/s) | = |
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| Family Room | x 10 cfm (or 5 L/s) | = |
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Recreation Room |
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x 10 cfm (or 5 L/s) | = |
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Other |
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x 10 cfm (or 5 L/s) | = |
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Kitchen |
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x 10 cfm (or 5 L/s) | = |
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Bathroom |
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x 10 cfm (or 5 L/s) | = |
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Laundry Room |
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x 10 cfm (or 5 L/s) | = |
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Utility Room |
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x 10 cfm (or 5 L/s) |
= |
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Total Ventilation Requirement |
= |
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Air Change Per Hour (ACH) Method
Formula:
TOTAL cubic feet × 0.35 per hour = total cubic feet per hour
Take total and divide by 60 to get cubic feet per minute (CFM)
Example:
A 25 ft. × 40 ft. (1,000 sq. ft.) house with basement
1,000 sq. ft. × 8 ft. high × 2 (1st floor + basement) = 16,000 cu. ft.
16,000 cu. ft. × 0.35 ACH = 5,600 cubic feet per hour
5,600 cu. ft. ÷ 60 minutes = 93 cubic feet per minute (CFM)
Result:
93 CFM is your ventilation need
Ventilation Rates Per Hour
To determine the ventilation rate (minutes per hour), divide the continuous ventilation rate calculated above by the dehumidifier's ventilation capacity found in the table below. The ventilation capacity of the dehumidifier is determined by the model, damper configuration, and static pressure.
| 0.0" WC | 0.5" WC | ||||||
| No Dampers | With Return Damper | No Damper | With Return Damper | ||||
| CFM | L/S | CFM | L/S | CFM | L/S | CFM | L/S |
| 320 | 151 | 260 | 123 | 150 | 71 | 140 | 66 |
| 0.0" WC | 0.5" WC | ||||||
| No Dampers | With Return Damper | No Damper | With Return Damper | ||||
| CFM | L/S | CFM | L/S | CFM | L/S | CFM | L/S |
| 370 | 175 | 280 | 132 | 180 | 85 | 170 | 80 |
Example
Calculated Continuous Ventilation Rate: 105 CFM
Dehumidifier Configuration:
Model: DHM090
Damper Configuration: With Return Damper
Static Pressure: 0.5" WC
Ventilation Capacity: 140 CFM
Ventilation Rate Calculation: 60 min x (105 CFM / 140 CFM) = 45 min
Result:
Ventilation Rate = 45 min