Setup, alerts, troubleshooting and plan limits.
Contact sensors have alarms auto-configured — you'll receive push notifications and SMS immediately when a contact closes.
If you need to change the WiFi network or move a sensor:
Monitors temperature, humidity, and barometric pressure. Optional external probe for freezers and coolers.
| Feature | Specification |
|---|---|
| Temperature range (ambient) | -40°C to +85°C (+/- 0.5°C) |
| Temperature range (probe) | -55°C to +125°C (+/- 0.5°C) |
| Humidity range | 0-100% RH (+/- 3%) |
| Barometric pressure | 300-1100 hPa |
| Power | USB-C, 5V |
| WiFi | 2.4 GHz (802.11 b/g/n) |
| Reporting interval | 1 to 30 minutes (configurable, default 15 min) |
Monitors dry contact closures — alarm panels, float switches, door contacts, or any normally-open dry contact. Sends an alert the instant the contact closes.
| Feature | Specification |
|---|---|
| Input | Dry contact (normally open) |
| Response time | Under 1 second |
| Connection | Screw terminal (D and G pins) |
| Alarm behavior | Latching — requires acknowledgment in app |
| Power | USB-C, 5V |
| WiFi | 2.4 GHz (802.11 b/g/n) |
Download the Fahren app for real-time monitoring, push notifications, and alarm acknowledgment:
You can also use the web dashboard from any browser.
| Alert | Trigger | Auto-resolve? |
|---|---|---|
| Temperature High | Temperature exceeds your set threshold | Yes |
| Temperature Low | Temperature drops below your set threshold | Yes |
| Humidity High | Humidity exceeds your set threshold | Yes |
| Humidity Low | Humidity drops below your set threshold | Yes |
| Sensor Offline | No data received within the configured timeout | Yes |
| Contact Closed | Dry contact closes (alarm triggered) | No — requires ACK |
Environmental alerts support duration filtering — you can require the condition to persist for a set number of seconds before triggering. This prevents false alarms from brief, transient changes.
Contact closure alerts are latching — they remain active until you acknowledge them in the app by tapping the ACK button. The alarm sound and vibration stop on ACK, and the alert resolves once the contact returns to normal.
If the contact clears and then closes again, that counts as a separate event and alerts you again, even if you never acknowledged the first one. A dry contact that cycles repeatedly is usually the earliest warning that equipment is failing, so each closure is recorded rather than folded into the first alert.
Each contact sensor has three timing settings, found under the sensor's Settings screen in the app:
| Setting | What it does | Default |
|---|---|---|
| Trigger Delay | How long the contact must stay closed before it alerts at all. Filters momentary contact. | None |
| Re-arm Delay | After an alarm clears, how long to wait before alerting again. If the contact is still closed when the wait ends, the alarm fires. | Off |
| Remind If Still In Alarm | Re-alerts you if you acknowledged an alarm and the contact never returned to normal. | Off |
Fahren can alert you through push notifications and SMS text messages. Both can be turned on or off per sensor. They are not redundant — each fails in a different way, which is why we recommend enabling both on anything critical.
| Push Notification | SMS Text | |
|---|---|---|
| Speed | Immediate | Usually seconds, but can be delayed by the carrier |
| Cost | Free, unlimited | Per message |
| Can it make noise? | Yes — plays your chosen alarm tone on a loop until acknowledged | No — only your normal text tone |
| Works if the app is closed or force-stopped? | No | Yes |
| Needs internet on your phone? | Yes | No — works on cell signal alone |
In short: push is what wakes you up, SMS is what still reaches you when the app can't. Push drives the looping alarm tone and vibration, and it is free, so it is the primary channel. But if your phone loses data, or the operating system closes the app to save battery, push cannot reach you — and that is exactly when a text message still arrives.
For critical equipment, Fahren can telephone you when an alarm goes unacknowledged. This is the most reliable alert we have: a ringing phone gets through when a notification does not, and it reaches people who do not have the app installed.
How it works:
Set this up on the web dashboard: open a sensor and choose Call Escalation. You can order the call list, set how long to wait before calling, and give each person on-call hours so a night contact is not phoned during the day.
Both iPhone and Android silence notifications in Do Not Disturb, Focus and silent mode. There is one setting that fixes this for Fahren alerts, and it takes a minute:
Save this number as a contact named Fahren Alarm:
+1 (231) 412-9670
iPhone: Contacts → Fahren Alarm → Edit → Ringtone → turn on Emergency Bypass. Repeat under Text Tone. Alarm calls and texts will now ring at full volume even in Do Not Disturb or silent mode.
Android: mark the contact as a Favourite (star it), then Settings → Notifications → Do Not Disturb → Calls → allow Starred contacts. Exact wording varies by phone.
SMS is off until you turn it on, and there are two switches — both must be on before a text can reach you. This is the most common reason someone opts in and still gets nothing.
1. Turn on SMS for your account (once):
+1XXXXXXXXXXYour number locks once consent is given. To change it, tap Edit — that clears your consent, so you will need to accept again for the new number.
2. Turn on SMS for each alarm (per sensor):
SMS is off by default on every alarm, including on sensors you already own. Contact sensors auto-create their alarms, so check the SMS switch there too.
Texts come from +1 231-412-9670. Save it as a contact so alerts are not mistaken for spam. A message looks like:
Fahren: Walk-in Cooler - Temperature above 40F (currently 44.2F). Reply STOP to opt out.
Replying STOP opts you out at the carrier level, so the toggle in the app will show off next time you open Settings. Standard message and data rates apply. Message frequency depends on how often your sensors alarm. SMS is optional and is not required to use Fahren. See our SMS Terms and Privacy Policy.
How far back you can look depends on your plan. What gets recorded does not — your sensors always record everything, on every plan.
Nothing is ever deleted when you downgrade. Older readings are simply hidden from view, and they all reappear the moment you upgrade again. If you want data genuinely erased, there is an explicit history wipe — it is permanent and asks you to type a confirmation.
Basic monitoring for up to four sensors is included at no charge. A subscription is optional.
Nothing sudden, and nothing silent:
You choose which sensors use your covered slots — it is not decided for you.
Nothing changes while we retry. Card retries run for two to three weeks and your monitoring is untouched the entire time. If the subscription does eventually lapse, your account drops to the free plan and your first four sensors keep monitoring permanently. A card expiring will never cost you your freezer.
Share sensors with other Fahren users:
Each team member can set their own alert thresholds independently.
+1XXXXXXXXXX format — US numbers only for nowDealers and installers can manage their customers through the Dealer Portal:
The full program — how installs and handover work, who owns what, and what your customers pay — is in the Dealer Program tab inside the Dealer Portal, and summarised publicly at fahrensense.com/dealers.
Your dealer account is free and unlimited. Contact sales@fahrensense.com to become a dealer.
Need help? Email us at support@fahrensense.com