Midea M-thermal Mono Series, Installation And Owner'S Manual

Page: 65 / 98

62
Symptom 3: Pump is making noise (cavitation)
Symptom 4: The water pressure relief valve opens
POSSIBLE CAUSES CORRECTIVE ACTION
There is air in the system. Purge air.
Water pressure at pump
inlet is too low.
• Check the water pressure.
The water pressure must be > 1 bar (water is cold).
• Check that the expansion vessel is not broken.
• Check that the setting of the pre- pressure of the expansion
vessel is correct (refer to "9.4.2 Water volume and sizing expansion
vessels").
POSSIBLE CAUSES CORRECTIVE ACTION
The expansion vessel is broken. Replace the expansion vessel.
The filling water pressure
in the installation is
higher than 0.3MPa.
Make sure that the filling water pressure in the installation is about
0.10~0.20MPa (refer to "9.4.2 Water volume and sizing expansion
vessels").
Symptom 6: Space heating capacity shortage at low outdoor temperatures
Symptom 5: The water pressure relief valve leaks
POSSIBLE CAUSES CORRECTIVE ACTION
Dirt is blocking the water
pressure relief valve
outlet.
Check for correct operation of the pressure relief valve by turning the red
knob on the valve counter clockWise:
• If you do not hear a clacking sound, contact your local dealer.
• In case the water keeps running out of the unit, close both the
water inlet and outlet shut-off valves first and then contact your
local dealer.
POSSIBLE CAUSES CORRECTIVE ACTION
Backup heater operation
is not activated.
Too much heat pump
capacity is used for
heating domestic hot
water (applies only to
installations with a
domestic hot water tank).
Check that the "t_DHWHP_MAX" and "t_DHWHP_RESTRICT" are
configured appropriately:
• Make sure that the "DHW PRIORITY" in the user interface is
disabled.
• Enable the "T4_TBH_ON" in the user interface/FOR SERVICEMAN
to activate the booster heater for domestic water heating.
Check that the "OTHER HEATING SOURCE/ BACKUP HEATER"is
enabled, see "10.6 Field settings" Check whether or not the thermal
protector of the backup heater has been activated (refer to "Controls parts
for backup heater(IBH)" ). Check if booster heater is running, the backup
heater and booster heater can’t operate simultaneously.
Symptom 7: Heat mode can’t change to DHW mode immediately
POSSIBLE CAUSES CORRECTIVE ACTION
Volume of tank is too
small and the location of
water temperature probe
not high enough
• Set "dT1S5" to maximum value, and set "t_DHWHP_RESTRICT" to
minimum value.
• Set dT1SH to 2 °C.
• Enable TBH, and TBH should be controled by the outdoor unit.
• If AHS is available, turn on first, if requirement for
turn heat pump on is fullfilled, the heat pump will turn on.
• If both TBH and AHS are not available, try to change the postion
of T5 probe(refer to 2 "General introduction").