Vaillant geoTHERM Installation Instructions

Fault diagnosis and rectification
Installation instructions geoTHERM 0020051574_04 99
11
11.4 Fault with temporary switch-off
The compressor shuts down, the heat pump remains in
operation. The compressor can start again after 5 min. at
the earliest. (see below for exceptions).
Fault code Error text/description Possible cause Solution
20 Heat source frost protect moni-
toring source outlet
Heat source temperature spread
(T3 - T8) > set value "Perm.
temp. spread"
This fault message is deacti-
vated by default and can only
be activated via vrDIALOG
parameter "Perm. temp.
spread" (20 K spread means
deactivated).
Brine pump faulty, temperature sen-
sor T8 or T3 faulty.
Too little volume flow in the brine
circuit.
Air in the brine circuit.
> Check heat source flow rate.
> Check the quality of plug contact on the cir-
cuit board and on the cable harness.
> Check sensors for correct operation (resist-
ance measurement based on VR 11 character-
istics, see attachment).
> Replace the sensors.
> Check the volume flow of the brine pump
(optimum spread approx. 3-5 K).
> Bleed the brine circuit.
21
(VWW only)
Heat source frost protect moni-
toring source outlet
Source outlet temperature T8
too low (<4 °C)
Temperature sensor T8 faulty.
No/full dirt filter in source return.
> Check the temperature level of the heat
source.
> Check the quality of plug contact on the cir-
cuit board and on the cable harness.
> Check sensors for correct operation (resist-
ance measurement based on VR 11 character-
istics, ¬Tab. 17.2.
> Replace the sensors.
> Check the volume flow of the well pump
(optimum spread approx. 3-5 K).
> Fit/clean dirt filter.
22
(VWS only)
Heat source frost protect moni-
toring source outlet
Source outlet temperature T8
too low (< Freeze protect temp.
parameter in Menu A4)
Brine pump faulty, temperature sen-
sor T8 faulty.
Too little volume flow in the brine
circuit.
Air in the brine circuit.
> Check heat source flow rate.
> Check the quality of plug contact on the cir-
cuit board and on the cable harness.
> Check sensors for correct operation (resist-
ance measurement based on VR 11 character-
istics, see attachment).
> Replace the sensors.
> Check the volume flow of the brine pump
(optimum spread approx. 3-5 K).
> Bleed the brine circuit.
23
(VWW only)
No ground water flow
Integrated flow switch does not
detect any volume flow
Filter in the heat source circuit
blocked.
Well pump faulty.
Motor protection switch on the well
pump has tripped.
Flow switch faulty or not connected.
> Cle
an the filter.
> Check the correct operation of the well
pump, and replace if necessary.
> Check the well pump for overload, e.g.
through jamming of phase failure.
> Check the well pump, sluice and motor pro-
tection switch, and replace if necessary.
> Check the correct operation of the flow
switch.
11.3 Fault with temporary switch-off

Vaillant geoTHERM Specifications

General

Brand	Vaillant
Model	geoTHERM
Category	Heat Pump
Language	English