Transcript Short Rules of Unico

Plenum
• Plenum design is based on Equal Static
Pressure using Static Regain
• Most duct systems are designed to
maintain Equal Friction or Equal Velocity
• Static Regain – robs the energy from the
moving air (high velocity) to create static
pressure to over come friction in the duct
so that equal pressure is obtained.
Short Rules of Unico
A Summary
Airflow
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Airflow
Airflow
Airflow
A MINIMUM OF 200 CFM per ton MUST
be maintained at all times
Not Equal Friction
This is what most think of for
Warm Air Systems
Unico System Uses Static
Regain
An Example of Static Regain
Plenum Sizing
Diameter
Max CFM
Typical Model
7”
700
1218 or 2430
9”
1000
3642
10*
1300
4860
These are MINIMUMS, to be safe you
can always use 10”
Plenum Length – Rule of Thumb
• Plenum can be up to 150’ equivalent
length
• First Tee = 30’
• All other = 15’
• Elbows = 15’
60/40 Rule
• Split 50/50, no more than 60/40
• Applies to all tees
70/30 RULE
• No more than 30% of CFM on side branch
24 Inch Rule
Space Takeoffs evenly
For Every 5 feet Over 10
You Lose 10% of Capacity
Keep runs at 12 feet or less
(if possible)
The longer the run the
less air is delivered
Steps to a Unico Layout
• 1. Do a total load calculation for the
buildings
• 2. Do a room by room load calculation
• 3. Determine where the air handler/return
will go
• 4. Run the plenum as long as you can to
connect the tubing
• 5. “Connect the Dots”