51
8. Troubleshooting
No.
Fault symptom
Possible cause
Explanation - Solution
9
Water heating takes
longer.
1. Heat pump not working.
1. Check heat pump – consult outdoor unit service manual.
2. Booster heater cut-out tripped.
2. Check booster heater thermostat and press reset button if safe.
3. Booster heater breaker tripped.
3. Check the cause and reset if safe.
4. The booster heater thermal cut-out has
tripped and cannot be reset using the manual
reset button.
4. Check resistance across the thermal cut-out, if open then connection is broken
and the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
5. Immersion heater cut-out has been triggered.
5. Check immersion heater thermostat and press reset button located on immersion
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.
6. Immersion heater breaker tripped.
6. Check the cause and reset if safe.
7.
Decreased flow rate in DHW circuit.
(Only when the external plate HEX for DHW is
used.)
7. Check the water circulation pump 4 (DHW).
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
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
1. Take the following measures.
• Retighten the nuts holding the pipes onto the DHW tank.
• Replace seal materials.
• Replace the pipes.
2.
Insulation material coming loose or off.
2. Fix insulation.
3.
3-way valve failure
3. Check plumbing/wiring to 3-way valve.
(i) Manually override 3-way valve using the main remote controller. (Refer to
<Manual operation> in section 7.2.) 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.)
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 in the service manual 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. Check settings and change as appropriate.
2.
Check the battery power and replace if flat.
3. The temperature sensor is located in a room
that has a different temperature relative to
that of the rest of the house.
3. Relocate the temperature sensor to a more suitable room.
4. Heat pump not working.
4. Check heat pump – consult outdoor unit service manual.
5. Booster heater cut-out tripped.
5. Check booster heater thermostat and press reset button if safe.
6. Booster heater breaker (ECB1) tripped.
6. Check the cause of the trip and reset if safe.
7. The booster heater thermal cut-out tripped
and can not be reset using the manual reset
button.
7. Check resistance across the thermal cut-out, if open then the connection is broken and
the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
8. Incorrectly sized heat emitter.
8. Check the heat emitter surface area is adequate
Increase size if necessary.
9. 3-way valve failure
9. Check plumbing/wiring to 3-way valve.
10. Battery problem (*wireless control only)
10.
Check the battery power and replace it flat.
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.
11.
Increase the flow rate between the mixing tank and the heat exchanger decrease
that between the mixing tank and the local system.
Summary of Contents for PAC-SIF051B-E
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