GCH15010
44
No.
Fault symptom
Possible cause
Explanation - Solution
10 Temperature of DHW
tank water dropped.
When DHW operation is not running, the DHW
tank emits heat and the water temperature
decreases to a certain level. If water in the DHW
-
cant drop in water temperature, check for the
following.
1. Insulation material coming loose or off.
1. Fix insulation.
2. 3-way valve failure
2. Check plumbing/wiring to 3-way valve.
(i) Manually override 3-way valve using the main remote controller. (Refer to
<Manual operation> in section 9-4.) If the valve does not still function, go to (ii)
below.
(ii) Replace 3-way valve motor. If the valve does not still function, go to (iii) be-
low.
(iii) Replace 3-way valve. (Refer to 11. DISASSEMBLY PROCEDURE.)
11 Hot or warm water
from cold tap.
Heat of hot water pipe is transferred to cold water
pipe.
Insulate/re-route pipework.
12 Water leakage
1. Poorly sealed connections of water circuit
components
1. Tighten connections as required.
2. Water circuit components reaching the end of
life
2. Refer to PARTS CATALOG for expected part lifetimes and replace them as
necessary.
13 Heating system does
not reach the set
temperature.
1. Prohibit, schedule timer or holiday mode se-
lected.
1. Check settings and change as appropriate.
2. The temperature sensor is located in a room
that has a different temperature relative to
that of the rest of the house.
2. Relocate the temperature sensor to a more suitable room.
3. Heat pump not working.
3. Check heat pump – consult outdoor unit service manual.
4. Booster heater cut-out tripped.
4. Check booster heater thermostat and press reset button if safe.
Reset button is located on the side of booster heater, covered with black rub-
ber cap. (See 4. PART NAMES AND FUNCTIONS for position.)
5. Booster heater breaker (ECB1) tripped.
5. Check the cause of the trip and reset if safe.
6. The booster heater thermal cut-out tripped
and can not be reset using the manual reset
button.
6. Check resistance across the thermal cut-out, if open then the connection is bro-
ken and the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
7. Incorrectly sized heat emitter.
7. Check the heat emitter surface area is adequate
Increase size if necessary.
8. 3-way valve failure
8. Check plumbing/wiring to 3-way valve.
(i) Manually override 3-way valve using the main remote controller. (Refer to
<Manual operation> in 9-4). If the 3-way valve does not function, go to (ii) below.
(ii) Replace 3-way valve motor. If the 3-way valve coil is replaced but the
3-way valve does not function go to (iii) below.
(iii) Replace 3-way valve. (Refer to 11. DISASSEMBLY PROCEDURE.)
9. Battery problem (*wireless control only)
9.
tank is reheated frequently because of a signifi-
Check the battery power and replace if flat.
14 In 2-zone value ON/
OFF control, only
Zone2 does not
reach the set tem-
perature.
1. When Zone1 and Zone2 are both in heating
mode, the hot water temperature in Zone2
does not exceed that in Zone1.
1. Normal action no action necessary.
2.
Faulty wiring of 2-way valve
2.
Refer to installation manual, "5.3 2-zone valve ON/OFF control".
3.
Faulty installation of 2-way valve
3.
Check for correct installation. (Refer to the manual included with each motor-
ized mixing valve.)
4.
Incorrect setting of Running time
4.
Check for correct setting of Running time.
5.
2-way valve failure
5.
Inspect 2-way valve. (Refer to the manual included with each 2-way valve.)
