Salus Thermostat Not Working? Troubleshooting Common Issues

By / July 20, 2025

Salus thermostats are known for being affordable, but sometimes things can go wrong, and you may encounter problems. This guide breaks down some common faults and how to fix them. If your heating isn’t coming on, if your receiver is flashing red, or the thermostat isn’t pairing, we cover how to hopefully fix your thermostat. Most of this applies to popular Salus models, such as the RT500RF, RT510TX, RT520TX, and the IT500.

Table of Contents

1. Thermostat Screen is Blank or Won’t Turn On

If your thermostat screen is blank and doesn’t respond after changing the batteries, try the following:

  • Use quality alkaline batteries like Duracell – avoid cheap zinc ones.
  • Make sure the polarity is correct (plus and minus the right way round).
  • Don’t press buttons while inserting the batteries.
  • If the screen remains blank, remove the batteries for at least 30 minutes before reinserting them.
  • Try pressing the small reset button (usually located in a pinhole on the thermostat case).

If it still doesn’t power up, chances are the thermostat has failed and will require replacement.

2. Salus Thermostat Not Pairing with Receiver

If your thermostat says “SYNC” or counts down but the receiver doesn’t respond:

  1. Turn off mains power to the receiver at the fused spur (not just the manual switch).
  2. Remove the thermostat batteries.
  3. Wait a few minutes.
  4. Turn the receiver power back on.
  5. Reinsert batteries into the thermostat.
  6. Start the pairing process (usually involves pressing a ‘pair’ or ‘test’ button).
Pairing process for a Salus RT510

If it doesn’t work, check if both devices are set to the same frequency (sometimes controlled by DIP switches or jumpers inside the units). Only change these if you’re confident and have the manual to hand.

3. Heating On Thermostat but Radiators Cold

In cases where the flame icon shows on the thermostat, but the boiler doesn’t fire:

  • Check the receiver – the red light means it’s powered, the green light means it’s receiving a signal.
  • If the green light isn’t coming on, it’s likely a communication issue.
  • If the green light is on but the boiler doesn’t respond, the relay inside the receiver may have failed.
  • Try switching the receiver to ‘manual’ – this should force the heating on.

If that works, then it means the thermostat isn’t communicating properly with the receiver. If that’s the case, then you can try re-pairring the thermostat and the receiver together. If this still doesn’t resolve the issues, then it may be time to consider replacing the receiver or possibly the entire system (receiver and thermostat).

4. Red Light Flashing on Salus Receiver

A flashing red light on the receiver indicates that the receiver hasn’t heard from the thermostat for over an hour. This can be caused by:

  • The batteries in the thermostat are weak and need replacing
  • Interference from nearby devices (Wi-Fi routers, smart doorbells)
  • Signal range problems (especially if the thermostat is far from the receiver or behind thick walls)

Move the thermostat closer to the receiver. If the red flashing stops and the green light appears, then the problem is most likely interference with the signal, or the range between the thermostat and the receiver is too far.

If that is the case, then you need to relocate the thermostat closer to the receiver or if interference continues then, if possible, change the RF address (refer to the manual for instructions on how to change the RF address).

5. Salus Thermostat Not Working After Battery Change

If the thermostat has stopped working after replacing the batteries, then:

  • Double check that you are using alkaline batteries.
  • Try removing the batteries for 30 minutes to allow a reset.
  • Ensure that the battery contacts are clean and not corroded.

Some models need resetting after a battery change. Some models have a reset button, which will reset the device once pressed. For those models without a reset button, you can try holding both arrow buttons down, and hopefully that will trigger a soft reset.

6. Replacing Your Salus Thermostat

If, despite your troubleshooting, you continue to have issues, then you may want to consider replacing your thermostat. Before purchasing a new thermostat, it is essential to double check that the replacement thermostat is compatible with existing system wiring, and of course, your boiler.

7. Can You Leave the Receiver in Manual Mode Overnight?

Yes, you can set the receiver to manual to get heat, but it’s not ideal. In manual mode, the boiler will stay on continuously, unless you adjust the radiator valves. If it must be left on all night, then it’s best to lower the flow temperature on the boiler to prevent overheating. This will also reduce energy wasted. Setting the temperature to around 50-55°C is probably a reasonable balance.

Summary: Common Salus Troubleshooting Tips

  • Blank screen? Use alkaline batteries and perform a 30 minute reset.
  • Not pairing? Power off both units, reset. If that doesn’t work, try resetting and re-pairing the receiver and the thermostat.
  • Red light flashing? Lost signal – could be batteries or interference.
  • Green light on, no heat? Faulty receiver relay or boiler wiring.
  • Still stuck? Manual mode can get you heat while you troubleshoot.

Salus thermostats can be temperamental. With some persistence, you can often get them going again – but if you’re constantly fighting the same problems, replacing the system may save you a lot of hassle in the long run.