Rotex RHBH04CB3V - Symptom: the Pump Is Making Noise (Cavitation); Symptom: the Pressure Relief Valve Opens; Symptom: the Water Pressure Relief Valve Leaks; Symptom: the Space Is NOT Sufficiently Heated at Low Outdoor Temperatures

12 Troubleshooting
Installer reference guide
79
RRLQ004~008CA + RHBH/X04+08CB
ROTEX HPSU low temperature Bi‑bloc
4P384979-1C – 2017.04
Possible causes Corrective action
The preferential kWh rate power
supply settings and electrical
connections do NOT match
This should match with the
connections as explained in
"6.5Preparing electrical
wiring"on page27 and "7.9.7To
connect the main power
supply"on page40.
The preferential kWh rate signal
was sent by the electricity
company
Wait for the power to return (2
hours max.).
12.3.3 Symptom: The pump is making noise
(cavitation)
Possible causes Corrective action
There is air in the system Purge air manually (see "To
perform a manual air purge"on
page74) or use the automatic air
purge function (see "To perform
an automatic air purge"on
page74).
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 "6.4.4 Changing the pre-
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 and
"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 backup heater overcurrent
fuse has not been turned off. If
it has, check the fuse and turn
it back on.
▪ The thermal protector of the
backup heater has not been
activated. If it has, check the
following, and then press the
reset button in the switch box:
▪ The water pressure
▪ Whether there is air in the
system
▪ The air purge operation
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]
There is air in the system. Purge air manually or
automatically. See the air purge
function in the "Commissioning"
chapter.