What this article covers
This article explains:
- What happens to the thermostat time during a power cut.
- How long the thermostat can retain its time without power.
- What happens after an extended power cut.
- What happens if the thermostat is connected to the Heatmiser app.
- The battery backup used on a neoStat V1.
- What to consider if you regularly experience power cuts.
What this article does not cover
This article does not cover:
- A thermostat with a completely blank display.
- A thermostat that has power but will not operate the heating.
- A thermostat showing offline in the app.
- A neoHub showing offline.
- Thermostats losing their schedules for reasons unrelated to a power cut.
- Electrical faults causing repeated loss of power to the heating system.
What Happens During a Short Power Cut?
The thermostat has an internal capacitor which provides temporary backup when the mains power is lost.
During a short power cut, the capacitor will keep the thermostat's time for a few hours.
When the power comes back on, the thermostat should therefore still remember the correct time.
If the power remains off for longer than the capacitor can maintain the clock, the thermostat may lose its time.
What Happens During an Extended Power Cut?
If you have an extended power cut, the thermostat's internal capacitor will eventually run out of stored power.
When this happens, the thermostat can lose its time.
Once mains power is restored, the thermostat will switch back on, but its displayed time may no longer be correct.
My Thermostat Is Connected to the Heatmiser App
If the thermostat is connected to a neoHub and the Heatmiser app, you normally do not need to manually correct the time after an extended power cut.
Once power and the neoHub connection have been restored, the neoHub will update the thermostat time automatically overnight.
Allow the system to remain powered and connected overnight, then check the thermostat again.
My Thermostat Is Not Connected to the Heatmiser App
If the thermostat is not connected to a neoHub and has lost its time following an extended power cut, the time will need to be corrected manually on the thermostat.
If power cuts are rare, no additional equipment should normally be required.
If you experience frequent or extended power cuts, continue to the section below.
neoStat V1 Battery Backup
The neoStat V1 is different because it has a replaceable battery backup for retaining the time during a loss of mains power.
If a neoStat V1 repeatedly loses its time during power cuts, the backup battery may need replacing.
After replacing the backup battery, monitor the thermostat during any future loss of mains power to confirm that it continues to retain its time.
I Regularly Have Power Cuts
If the property regularly suffers from power cuts, we would recommend considering a UPS, or Uninterruptible Power Supply, for the heating controls.
A UPS provides temporary backup power when the mains electricity supply is interrupted.
Depending on the installation, a UPS could be considered for:
- The heating control system.
- The neoHub and associated equipment.
- A larger section of the electrical installation.
- The property as a whole, where appropriate.
The purpose is to prevent the heating controls and other equipment from repeatedly losing power, which can result in devices losing their time or schedules during extended outages.
A suitably qualified electrician should advise on the correct UPS arrangement for the installation.
What Happens Next?
If the thermostat retains its time after a short power cut, no further action is required.
If an app-connected thermostat loses its time after an extended power cut, allow the neoHub and heating system to remain powered and connected overnight. The time should update automatically.
If you have a neoStat V1 that no longer retains its time during a power cut, check the replaceable backup battery.
If the property regularly experiences extended power cuts, consider having a suitable UPS installed to maintain power to the heating controls.
If the thermostat continues to lose its time when there has not been a power cut, the guidance in this article has no further troubleshooting steps. Please speak to an adviser who can assist further.