Mitsubishi Electric City Multi PWFY-P36NMU-E-BU Data Book page 59

15. INSTALLATION
Caution for water pipe installation
Consider the following when designing and installing a water piping system.
 Do not use steel pipes as water pipes.
- Copper pipes or stainless steel pipes are recommended. If iron pipes are used in the existing system, do not connect
a new circuit to the old one. Keep the existing and new circuits separate.
 Light pipes are similar to other air-conditioning pipes, however, please observe the following precautions during installation.
 Before a long period of non use, purge the water out of the pipes and thoroughly let them dry.
 Use a closed water circuit.
 When operating the unit, add brine to the circulating water to prevent it from freezing. To use brine in the system, DipSW 1-10
must be set to ON.
 When installed in a low-ambient temperature environment, keep the water circulating at all times. If that is not possible, purge
the water out of the pipes completely.
 Do not use the water used for this unit for drinking or food manufacturing.
 When the ambient temperature is 0 ˚C (32 ˚F) or lower during stop operation, keep the water circulating at all times, or purge
the water out of the pipes completely.
Model
PWFY-P36NMU-E-BU
PWFY-P36NMU-E2-AU
PWFY-P72NMU-E2-AU
*1 When the attached expansion joints are installed.
Selecting a water pump
Use a pump that is large enough to compensate for the total water pressure loss and to supply sufficient water to the unit.
Installing the strainer
 Install the strainer at the angle of 45˚ or less as shown in [Fig. 3-1-A].
 Install the supplied strainer at the water inlet.
[Fig. 3-1-A]
Precautions during installation
 Use the reverse-return method to insure proper pipe resistance to each unit.
 To insure easy maintenance, inspection, and replacement of the unit, use a proper joint, valve, etc. on the water intake and
outlet port. In addition, be sure to install a strainer on the water intake pipe. (In order to maintain the heat source unit, a strainer
on the circulating water inlet is necessary.)
* An example of the heat source unit installation is shown in [Fig. 3-1-B].
 Install a suitable air vent on the water pipe. After sending water through the pipe, be sure to vent the excess air.
 Condensed water may form in the low-temperature sections of heat source unit. Use a drainage pipe connected to the drain
valve at the base of the unit to drain the water.
 Install a back flow-prevention valve on the pump and a flexible joint to prevent excess vibration.
 Use a sleeve to protect the pipes where they go through a wall.
 Use metal fittings to secure the pipes, and install them so that they have maximum protection against breakage and bending.
 Do not confuse the water intake and outlet valves.
 This unit doesn't have any heater to prevent freezing within tubes. When the water flow is stopped on low ambient, take out the
water from tubes.
 The unused knockout holes should be closed and the opening of refrigerant pipes, water pipes, power source and transmission
wires should be filled with putty and so on to prevent from rain. (field construction)
 Wrap some sealing tape around the screw part to prevent water leakage.
 Hold the pipe on the unit side in place with a spanner when installing the pipes or strainer.
Tighten screws to a torque of 50 N.m.
 Water pipes can get very hot, depending on the preset temperature. Wrap the water pipes with insulating materials to prevent
burns.
 Install the expansion joint (accessory) at the inlet after installing the strainer, and outlet.
MEES20K028
Water inlet
PT 3/4 Screw
PT 3/4 Screw
PT 1 Screw *1
Y-type strainer
AIR TO WATER
Water outlet
PT 3/4 Screw
PT 3/4 Screw
PT 1 Screw *1
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