The System Does Not Start/Operate - Daikin EGSQH10S18AA9W Service Manual

ESIE13-03 | Part 2. Troubleshooting
Possible failures
Root cause category: component - electrical
3-way valve blocked.
Deviation of tank thermistor
(R5T).

3.4. The system does not start/operate

Possible failures
Root cause category: software control
Thermostat ON conditions
for space heating are not
met.
Thermostat ON conditions
for domestic hot water
operation are not met.
Out of operation range
(brine temperature not
OK).
Page 42
Ground source heat pump
Root cause
Component failure.
Tank thermistor measures a
higher temperature than actual
(component failure).
Root cause
Thermostat ON conditions
for space heating are not
met.
Thermostat ON conditions
for domestic hot water
operation are not met.
Brine entering temperature
lower than freezing tem-
perature (Tf) + 6,5 K will
stop the unit.
Check
Check the 3-way valve (see
page 79).
Check tank thermistor (R5T)
(see page 58).
Check
Confirm thermostat on conditions depend-
ing on the unit control method (setting
C-07):
• Setting -1: External room thermostat
indicates by contact when to start/stop.
• Setting -2: Room thermostat control =>
compare setpoint with room thermistor
value. Thermo on: room temperature =
setpoint - (hysteresis/2).
Thermo off = room temperature +
(hysteresis/2). For setting of hysteresis
refer to setting 9-0C.
• Setting -3: Leaving water temperature
control => Thermo on: leaving water
temperature = setpoint. Thermo off:
leaving water temperature -1,5°C.
Confirm thermostat on conditions depend-
ing on the selected domestic hot water
(DHW) control type (setting [6-0D]):
1. Reheat only:
In case reheat setpoint is 55°C or lower:
domestic hot water will go thermo off
when reheat setpoint (setting [6-0C]) is
reached.
Domestic hot water will go thermo on
when reheat setpoint (setting [6-0C])
-10°C is reached.
In case reheat setpoint is higher than
55°C:
domestic hot water will go thermo off
when reheat setpoint (setting [6-0C])+
(setting [7-00]) is reached.
Domestic hot water will go thermo on
when reheat setpoint (setting [6-0C]) -
(setting [7-01]) is reached.
2. Schedule only:
domestic hot water will go thermo off
when setpoint (setting [6-0A] or [6-0B])
is reached.
Domestic hot water will only go thermo
on at time of schedule demand.
3. Schedule + reheat
combination of 1) and 2).
No action - unit cannot operate when
brine temperature becomes too low (risk
of freezing).
3. Symptom based troubleshooting
Corrective action
Replace the 3-way valve (see
page 125) and (see
page 128).
Replace thermistor R5T
(see"Replacing a thermistor
(except R10T)" on page
Corrective action
Change setpoint if
required.
Change setpoint if
required.
13/05/15 | Version 2.0
143).