1. Plumbing Systems CNST 305 Environmental Systems 1 Dr. Berryman
Sizing DWV
Plumbing Systems
CNST 305
Environmental Systems 1
Dr. Berryman
4bc
Drain, Waste, Vent
Chapter 2,5,6 Appendix C (Wentz) and  (Toa)   

2. Design Guidelines VENTS Above ground venting cannot be less than 1 ¼”
1 ¼” vent can handle on 1 DFU
Underground venting cannot be less than 2” in diameter
Vents must be a certain distance from the trap that it serves
An individual vent must not be less than ½ the size of the drain that it connects
An individual vent should not be larger than the drain that it connects
Downstream piping always bigger than the upstream section
A vent line must be 6” above flood level rim of the fixture before turning horizontal
Branch vents must slope toward a drain
Some codes require that at least one of the building’s VTR be 4” in diameter or larger
DRAIN/WASTE
All traps must be vented
The waste stack cannot be smaller the the largest horizontal branch connecting to the stack
At least one waste stack same as building drain
No branch pipe smaller than the one that proceeds it
Above ground cannot be less that 1¼”
Below ground cannot be less than 2”
1 ¼” drain pipe can handle on 1 DFU
A drain line cannot be smaller than the trap arm to which it is connected
Use 4” trap arm for floor mounted water closets

3. Sizing Drain Waste Determine number of plumbing fixtures to install
Layout fixtures in space to codes (ie ADA)
Determine site utilities
Generate isometric
Determine minimum trap size for each fixture (tbl 2-2)
Determine DFU
Add DFU values starting from the farthest end of system

4. Drain/Waste Iso Determine DFU… TDL 60o 90o 30o From Tbl 2-2 GIVEN:
Water Closet – Siphon jet w/ flushometer valve, pressure = 15 psi
Wall Urinal – Siphon jet with ¾” spud/flushometer
Lavatory
TDL = 100’
Determine DFU…
From Tbl 2-2

5. Determine Trap Size for Drains
From Table 2-2:
Water Closet = 3”
Wall Urinal = 2”
Lavatory = 1 ¼”

6. Add DFU
Water Closet = 6 DFU
Wall Urinal = 4 DFU
Lavatory = 1 DFU

7. Size Waste Branches

8. Sizing Waste (cont.)

9. Sizing Vents

10. Complete DWV Isometric

11. Sizing Circuit or Loop Vents

12. Next Time Test Review In class homework assignment
Review notes and reading
Able to use books/notes
Due 10 minutes before end of class
We will grade and review assignment
Next week – Start HVAC

13. GIVEN:
Water Closet – Siphon jet w/ flushometer valve, pressure = 15 psi
Wall Urinal – Siphon jet with ¾” spud/flushometer
Lavatory
TDL = 100’