Drain Line Connection - Pentair Autotrol 255 Installer Manual

Installer Manual 255/LOGIX 742-762-764 - Installation
5.8.

Drain line connection

Note
Standard commercial practices are expressed here. Local codes may require changes to
the following suggestions. Check with local authorities before installing a system.
The unit should not be more than 6.1 m from the drain. Use an appropriate adapter fitting to connect
12.7 mm plastic tubing to the drain line connection of the control valve.
If the backwash flow rate exceeds 22.7 lpm or if the unit is located 6.1-12.2 m from the drain, use
19 mm (3/4") tubing. Use appropriate fittings to connect the 19 mm (3/4") tubing to the 19 mm (3/4")
NPT drain connection on the valve.
The drain line may be elevated up to 1.8 m (6 ft) providing the run does not exceed 4.6 m and water
pressure at the softener is not less than 2.76 bar. Elevation can increase by 61 cm for each additional
0.69 bar of water pressure at the drain connector.
Where the drain line is elevated but empties into a drain below the level of the valve, form a 18 cm loop
at the far end of the line so that the bottom of the loop is level with the drain line connection. This will
provide an adequate siphon trap.
Where the drain empties into an overhead sewer line, a sink-type trap must be used.
Secure the end of the drain line to prevent it from moving.

Note
Waste connections or the drain outlet shall be designed and constructed to provide
connection to the sanitary waste system through an air-gap of 2 pipe diameters or 25.4 mm
(1"), whichever is larger.
Caution
Never insert the drain line directly into a drain, sewer line or trap. Always allow an air gap
between the drain line and the wastewater to prevent the possibility of sewage being back-
siphoned into the softener.
40 / 92
Air gap
Drain
Ref. MKT-IM-021 / A - 20.02.2019