Midea M thermal Mono Series Engineering Data page 46

- That the water treatment is correctly executed by a qualified water specialist.
- That a glycol with corrosion inhibitors is selected to counteract acids formed by the oxidation of glycols.
- That in case of an installation with a domestic hot water tank, only the use of propylene glycol is allowed. In
other installations the use of ethylene glycol is fine.
- That no automotive glycol is used because their corrosion inhibitors have a limited lifetime and contain
silicates that can foul or plug the system.
- That galvanized piping is not used in glycol systems since it may lead to the precipitation of certain elements in
the glycol's corrosion inhibitor
- To ensure that the glycol is compatible with the materials used in the system.
Freeze protection by freeze protection valves
When no glycol is added to the water, freeze protection valves can be used to drain the water from the system
before it can freeze.
- Install freeze protection valves (field supply) at all lowest points of the field piping.
- Normally closed valves (located indoors near the piping entry/exit points) can prevent that all water from
indoor piping is drained when the freeze protection valves open.
3.5 Water Flow Switch
Water may enter into the flow switch and cannot be drained out and may
freeze when the temperature is low enough. The flow switch should be
removed and dried, then can be reinstalled in the unit.
Counterclockwise rotation, remove the water flow switch.
Drying the water flow switch completely.
3.6 Adding Water
Connect the water supply to the fill valve and open
the valve.
Make sure the automatic air purge valve is open (at
least 2 turns). Refer to Figure 3-3.3.
Fill with water until the manometer indicates a
pressure of approximately 2.0 bars. Remove air in the
circuit as much as possible using the air purge valve.
Air in the water circuit could lead to malfunction of
the backup electric heater.
3.7 Water Piping Insulation
The complete water circuit including all piping, water piping must be insulated to prevent condensation during cooling
operation and reduction of the heating and cooling capacity as well as prevention of freezing of the outside water piping
during winter. The insulation material should at least of B1 fire resistance rating and complies with all applicable legislation.
The thickness of the sealing materials must be at least 13mm with thermal conductivity 0.039W/mK in order to prevent
freezing on the outside water piping. If the outdoor ambient temperature is higher than 30°C and the humidity is higher
than RH 80%, the thickness of the sealing materials should be at least 20mm in order to avoid condensation on the surface
of the seal.
202005
Figure 3-3.3: Air purge valve
Midea CAC Confidential
M thermal Mono
Figure 3-3.2: Water flow switch
Do not fasten the black
plastic cover on the vent
valve at the topside of the
unit when the system is
running. Open air purge
valve, turn anticlockwise at
least 2 full turn to release
air from the system.
Keep dry
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