Hot Water Piping Work - Panasonic 2WAY Multi U-16GE3E5 Manuel D'installation

5. HOT WATER PIPING WORK

Precautions on Hot Water Piping Work
• The allowable pressure for the hot water piping in the outdoor unit is 0.7 MPa.
• Attach water release valves and air release valves to the hot water piping at the appropriate locations. If air
becomes mixed with the fluid in the pipe, this could result in noise, corrosion, or reduced performance.
• Use a hot water circulation rate in the range from 35ℓ/min to 51ℓ/min.
If a circulation rate outside this range is used, this could result in a breakdown or air blockage in the pipe
due to corrosion or freezing of the heat exchanger.
• Be sure to fully perform the heat-retention work for DHW piping.
Failure to provide adequate heat retention will result in heat loss. This could also result in damage due to
freezing during periods of extreme cold.
• Attach the pump for DHW to the inlet piping side for DHW.
• For the DHW piping, select pipes with a connection port diameter of 27.2 mm or larger, and pay careful
attention to the flow rate. Route the piping by minimizing bends and pipe resistance, and use union joints
and similar parts near the outdoor unit so that the outdoor unit can be easily separated.
• Attach a strainer (80 mesh or higher) to the outdoor unit inlet pipe for protecting the DHW heat exchanger
in the outdoor unit. Also attach valves before and after the strainer and at the outlet pipe for maintenance
and servicing.
• Attach a temperature gauge and pressure gauge to the piping. These are needed for conducting checks of
the operation status and for maintenance.
• During test operation, attach a water temperature gauge and flow rate adjustment valve to the water piping
to enable adjusting of the hot water flow rate while watching the water temperature gauge. Also, do not
touch the adjustment valve once adjustment is complete.
• Attach pipe support fittings to the DHW pipes at appropriate locations so that no excessive loads are
applied to the outdoor unit.
• Select the pump for DHW based on the water pressure loss characteristics shown in the table below.
50
0 35
0 12.5
40
30
20
10
0
30 35
Hot Water Pipe Cleaning and Air Bleeding
• Be sure to always perform cleaning of the pipe system for removing dust, cutting debris, and other objects
inside the pipes and removing flux debris inside the pipes which can cause deterioration of antifreeze
solution and generation of gel compounds.
Be sure to fully bleed the air. If any air remains in the pipes, water will not flow, and the pipes cannot be
cleaned.
40 45
16.3 19.7
40
Circulation rate [ℓ/min]
Fig.20 Characteristic of Hot water pressure loss
EN - 21
50 55
24.6 29.7
45 50
60 65
34.8 40.6
55 60