Vaillant fault code F.685
Fault code F.685 on a Vaillant heat pump (including geoTHERM 3 kW) means: Thermostat VRC 470 was already detected, but the connection has been lost. Reset the appliance once. If the code comes back, a part is usually faulty. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code F.685 on a Vaillant heat pump indicates: Thermostat VRC 470 was already detected, but the connection has been lost.
Applies to
Vaillant geoTHERM 3 kW, VWS 36/4.1 230V.
Fault code F.685 on other Vaillant series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- F.685 on flexoTHERM, VWF 117/4, VWF 157/4, VWF 197/4, VWF 57 /4, VWF 87/4: System thermostat was already detected, but the connection has been lost.
- F.685 on aroTHERM Monoblock, VWL 115/2 A 400 V, VWL 155/2 A 400V, VWL 55/2 A 230V, VWL 55/3 A 230 V, VWL 85/2 A 230 V: The product is not connected to the thermostat, polarity reversed.
Matching parts
Vaillant parts are available from Instalpunt; shipping to EU countries from €17.95 (€24.95 for more distant countries), usually 3–5 working days.
Parts by Vaillant series: ecoTEC plus · ecoTEC pro.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Vaillant display cable for ecoTEC plus and ecoTEC pro etc. € 9.15
- Vaillant sealing ring for e.g. Hybrid Brine Split VWL 35/4 S 230V R1 0020151178 € 9.81
- Vaillant magnet for e.g. hrSOLIDE plus VHR 24-28/3-5 R3 0020068136 € 13.07
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does Vaillant heat pump fault code F.685 mean?
Thermostat VRC 470 was already detected, but the connection has been lost.
How do I fix fault code F.685 on a Vaillant heat pump?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for Vaillant fault code F.685?
That depends on the exact cause. In the Vaillant parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code F.685 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All Vaillant heat pump faults and codes at a glance →