Mitsubishi Electric QAHV-N560YA-HPB Data Book page 33

4. System Design
4-1-3. Pipe gradient and air venting valve (Outlet hot water pipe)
During the hot water storage operation, the air dissolved in the water is discharged in the form of bubbling from the outlet
hot water pipe to quickly raise low-temperature water to the required temperature. When the air accumulates in the pipe,
the resistance of the water circuit will increase and the flow rate will extremely decrease. Because of this, an installation of
automatic air venting valves is required when there is a pipe that slopes down in the outlet hot water pipe.
Install the pipe with an upward gradient of 1/200 or more toward the air vent to prevent air accumulation in the pipe.Also,
install air venting valves to the places where air can accumulate. The installation example is shown below.
If the crosscut pipe is located lower than the hot water outlet of the heat pump unit, raise the pipe near the unit and install
an automatic air venting valve.
Automatic air venting valve
Upward gradient 1/200
4-1-4. Outlet check valve (When installing multiple units)
When connecting multiple units with pipes in parallel, install a check valve at the outlet pipe of each unit. If a check valve is
not installed, a circuit in which warm water flows back will be created in some units during the defrost cycle or abnormal
stop, and other units will come to an abnormal stop due to sudden change of the inlet water temperature.
4-1-5. Water Pipe Hole Size and Location
Hot water outlet
(Bronze Rc3/4, female screw)
Water inlet
(Bronze Rc3/4, female screw)
MEES19K001
Air separator
Air venting valve installation example
122
199
Front view
Automatic air venting valve
Heat pump unit
Base
19
Service panel
54
Automatic air
venting valve
Hot water outlet
Crosscut pipe
9
26 26 54
755
Side view
32