Mitsubishi Electric ecodan ECOSLIM150L-PP-MEUK Installation Manual page 70

Troubleshooting
28
XXXXXXXX XXXXXXX
No. Fault Symptom
8 Cold water at tap.
9
Water heating takes
longer.
10 Temperature of DHW
tank water dropped.
Pre-Plumbed Slimline Cylinder Installation Manual
70
(continued)
Possible Cause
1. Hot water run out.
2. Prohibit, schedule timer or holiday
mode selected.
3. Heat pump not working.
4. Booster heater cut-out tripped.
5. The earth leakage circuit breaker for
booster heater breaker (ECB1) tripped.
6. The booster heater thermal cut-out
has tripped and cannot be reset
using the manual reset button.
7. Immersion heater cut-out tripped.
8. Immersion heater breaker (ECB2)
tripped.
9. Motorised valve fault
1. Heat pump not working.
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.
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 significant 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. Motorised valve failure
Explanation - Solution
1. Ensure DHW mode is operating and wait for DHW tank to re-heat.
2. Check settings and change as appropriate.
3. Check heat pump – consult outdoor unit service manual.
4. Check booster heater thermostat and press reset button if safe.
Reset button is located on the side of booster heater, covered with
white rubber cap. See component parts diagram (Installation manual of
Hydrobox, section 3.) to find out its position.
5. Check the cause and reset if safe.
6. 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.
7. Check immersion heater thermostat and press reset button, located on
immersion heater boss, if safe. If the heater has been operated with no
water inside it may have failed, so please replace it with a new one.
8. Check the cause and reset if safe.
9. Check plumbing/wiring to motorised valve.
(i) Manually override motorised valve using the main controller. (Refer to
<Manual operation> in section 7.2.) If the valve does not still
function, go to (ii) below.
(ii) Replace motorised valve coil. If the valve does not still function,
go to (iii) below.
(iii) Replace motorised valve. (Refer to the service manual.)
1. Check heat pump – consult outdoor unit service manual.
2. Check booster heater thermostat and press reset button if safe.
Reset button is located on the side of booster heater, covered with
white rubber cap. See component parts diagram (Installation manual
of Hydrobox, section 3.) to find out its position.
3. Check the cause and reset if safe.
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. 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. Check the cause and reset if safe.
1. Take the following measures.
• Retighten the nuts holding the pipes onto the DHW tank.
• Replace seal materials.
• Replace the pipes.
2. Fix insulation.
3. Check plumbing/wiring to motorised valve.
(i) Manually override 3-way valve using the main controller. (Refer to <Manual
operation> in section 7.2.) If the valve does not still function, go to (ii) below.
(ii) Replace motorised valve coil. If the valve does not still function, go to (iii) below.
(iii) Replace motorised valve. (Refer to the service manual.)