Mitsubishi Electric PAC-IF081B-E Installation Manual page 49

9. Troubleshooting
No. Fault symptom
9 Water heating takes 1. Heat pump not working.
longer.
2. Booster heater cut-out tripped.
3. Booster heater breaker tripped.
4. The booster heater thermal cut-out has
tripped and cannot be reset using the manual
reset button.
5. Immersion heater cut-out has been triggered.
6. Immersion heater breaker tripped.
7. Decreased flow rate in DHW circuit.
(Only when the external plate HEX for DHW is
used.)
10 Temperature of DHW When DHW operation is not running, the DHW
tank water dropped. tank emits heat and the water temperature
decreases to a certain level. If water in the DHW
tank is reheated frequently because of a signifi-
cant drop in water temperature, check for the
following.
1. Water leakage in the pipes that connect to
the DHW tank
2. Insulation material coming loose or off.
3. 3-way valve failure
11 Hot or warm water Heat of hot water pipe is transferred to cold water
from cold tap pipe.
12 Water leakage 1. Poorly sealed connections of water circuit
components
2. Water circuit components reaching the end of
life
13 Heating system does 1. Prohibit, schedule timer or holiday mode se-
not reach the set lected.
temperature.
2. Check settings and change as appropriate.
3. The temperature sensor is located in a room
that has a different temperature relative to
that of the rest of the house.
4. Heat pump not working.
5. Booster heater cut-out tripped.
6. Booster heater breaker (ECB1) tripped.
7. The booster heater thermal cut-out tripped
and can not be reset using the manual reset
button.
8. Incorrectly sized heat emitter
9. 3-way valve failure
10. Battery problem (*wireless control only)
11. If a mixing tank is installed, the flow rate
between the mixing tank and the heat ex-
changer is less than that between the mixing
tank and the local system.
14 In 2-zone tempera- 1. When Zone 1 and Zone 2 are both in heating
ture control, only mode, the hot water temperature in Zone 2
Zone 2 does not does not exceed that in Zone 1.
reach the set tem-
2. Faulty wiring of motorized mixing valve
perature.
3. Faulty installation of motorized mixing valve
4. Incorrect setting of running time
5. Motorized mixing valve failure
15 After DHW operation At the end of the DHW mode operation the 3-way
room temperature valve diverts hot water away from the DHW circuit
rises a little into space heating circuit.
This is done to prevent the system components
from overheating.
The amount of hot water directed into the space
heating circuit varies according to the type of the
system.
Possible cause
1. Check heat pump – consult outdoor unit service manual.
2. Check booster heater thermostat and press reset button if safe.
3. Check the cause and reset if safe.
4. Check resistance across the thermal cut-out, if open then connection is broken
5. Check immersion heater thermostat and press reset button located on immersion
6. Check the cause and reset if safe.
7. Check the water circulation pump 4 (DHW).
1. Take the following measures.
2. Fix insulation.
3. Check plumbing/wiring to 3-way valve.
Insulate/re-route pipework.
1. Tighten connections as required.
2. Refer to the parts catalog in the service manual for expected part lifetimes and
1. Check settings and change as appropriate.
2. Check the battery power and replace if flat.
3. Reposition the temperature sensor to a more suitable room.
4. Check heat pump – consult outdoor unit service manual.
5. Check booster heater thermostat and press reset button if safe.
6. Check the cause of the trip and reset if safe.
7. Check resistance across the thermal cut-out, if open then the connection is broken and
8. Check the heat emitter surface area is adequate
9. Check plumbing/wiring to 3-way valve.
10. Check the battery power and replace it flat.
11. Increase the flow rate between the mixing tank and the heat exchanger decrease
1.
2. Refer to "4.7 Wiring for 2-zone temperature control".
3. Check for correct installation. (Refer to the manual included with each motorized
4. Check for correct setting of running time.
5. Inspect the mixing valve. (Refer to the manual included with each motorized mix-
Normal operation no action necessary.
Explanation - Solution
and the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
heater boss, if safe. If the heater kept running with no water inside, this may have
resulted in failure, so replace it with a new one.
• Retighten the nuts holding the pipes onto the DHW tank.
• Replace seal materials.
• Replace the pipes.
(i) Manually override 3-way valve using the main remote controller. (Refer to
[Manual operation] in section 7. Remote controller) If the valve does not still
function, go to (ii) below.
(ii) Replace 3-way valve coil. If the valve does not still function, go to (iii) below.
(iii) Replace 3-way valve. (Refer to the service manual.)
replace them as necessary.
the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
Increase size if necessary.
that between the mixing tank and the local system.
Normal operation no action necessary.
mixing valve.)
ing valve.)
en
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