12 Troubleshooting
Installer reference guide
78
RRLQ004~008CA + RHBH/X04+08CB
ROTEX HPSU low temperature Bi‑bloc
4P384979-1 – 2015.01
12.3.3
Symptom: The pump is making noise
(cavitation)
Possible causes
Corrective action
There is air in the system
perform a manual air purge" on
page 73
an automatic air purge" on
page 73
The water pressure at the pump
inlet is too low
Check and make sure that:
▪ The water pressure is >1 bar.
▪ The manometer is not broken.
▪ The expansion vessel is NOT
broken.
▪ The pre-pressure setting of the
expansion vessel is correct
(see
pressure of the expansion
vessel" on page 26
12.3.4
Symptom: The pressure relief valve opens
Possible causes
Corrective action
The expansion vessel is broken
Replace the expansion vessel.
The water volume in the
installation is too high
Make sure that the water volume
in the installation is below the
maximum allowed value (see
"6.4.3 To check the water volume
and flow rate" on page 25
"6.4.4 Changing the pre-pressure
of the expansion vessel" on
page 26
The water circuit head is too high The water circuit head is the
difference in height between the
indoor unit and the highest point
of the water circuit. If the indoor
unit is located at the highest
point of the installation, the
installation height is considered
0 m. The maximum water circuit
head is 10 m.
Check the installation
requirements.
12.3.5
Symptom: The water pressure relief valve
leaks
Possible causes
Corrective action
Dirt is blocking the water
pressure relief valve outlet
Check whether the pressure
relief valve works correctly by
turning the red knob on the valve
counterclockwise:
▪ If you do NOT hear a clacking
sound, contact your dealer.
▪ If the water keeps running out
of the unit, close both the
water inlet and outlet shut-off
valves first and then contact
your dealer.
12.3.6
Symptom: The space is NOT sufficiently
heated at low outdoor temperatures
Possible causes
Corrective action
The backup heater operation is
not activated
Check and make sure that:
▪ The backup heater operation
mode is enabled. Go to:
▪ [A.5.1.1] > Installer settings
> Heat sources > Backup
heater > Operation mode
[4‑00]
▪ The thermal protector of the
backup heater has not been
activated. If it has, check:
▪ The water pressure
▪ Whether there is air in the
system
▪ The air purge operation
Press the reset button in the
switch box. See
for the location of the reset
button.
The backup heater equilibrium
temperature has not been
configured correctly
Increase the "equilibrium
temperature" to activate the
backup heater operation at a
higher outdoor temperature. Go
to:
▪ [A.5.1.4] > Installer settings >
Heat sources > Backup heater
> Equilibrium temp. OR
▪ [A.8] > Installer settings >
Overview settings [5‑01]
Too much heat pump capacity is
used for heating domestic hot
water (applies only to
installations with a domestic hot
water tank)
Check and make sure that the
“space heating priority” settings
have been configured
appropriately:
▪ Make sure that the "space
heating priority status" has
been enabled. Go to [A.8] >
Installer settings > Overview
settings [5‑02]
▪ Increase the "space heating
priority
temperature"
to
activate
backup
heater
operation at a higher outdoor
temperature. Go to [A.8] >
Installer settings > Overview
settings [5‑03]
12.3.7
Symptom: The pressure at the tapping
point is temporarily unusual high
Possible causes
Corrective action
Failing or blocked pressure relief
valve.
▪ Flush and clean the complete
tank
including
the
piping
between pressure relief valve
and the cold water inlet.
▪ Replace the pressure relief
valve.