HACCP — frequently asked questions

The questions that came up during the Slovakia pilot, with the answers we gave.

Do I need a different system for chilled vs frozen?

No. The HACCP vertical handles both. Each device's channel has its own operating range; a chilled fridge gets [-2 °C, +5 °C], a freezer gets [-24 °C, -18 °C]. The site as a whole is one OpenSense subscription.

How many sensors per fridge?

One is enough for compliance. Two is better if the fridge is large or old: place one near the warmest stored item (typically top-front) and one near the coldest (typically back-bottom). The two readings let you detect compressor short-cycling that a single probe misses.

Will the inspector ask for paper?

In Slovakia, ŠVPS inspectors we have worked with accept a PDF report printed on the spot. They want to see (a) the log exists, (b) the operator can produce it, (c) it covers the period. They do not require hand-written paper.

In other EU member states, regulators vary. Germany's BfR has accepted electronic logs since 2017. Austria's AGES accepts them when there is a periodic export (we recommend printing monthly).

We have not yet tested an inspection in France (DGAL) or Italy (NAS); if you are in one of those countries and would like to be the first, let us know — we will follow up.

What about transport?

OpenSense supports portable sensors with cellular fallback for vehicles. The device sits in the refrigerated cargo space; the cellular link reports back. The use case is well-supported by Efento LR-T-3 sensors with the cellular gateway accessory; pricier than the fixed-installation kit. Email us before buying.

My fridge does scheduled defrost cycles. False alarms!

Configure a time-of-day window on the rule that allows higher temperatures during the scheduled defrost. See Alerts API → time-of-day windows.

If the defrost is dynamic (compressor decides), use a longer grace period instead: defrost typically lasts < 20 minutes, so a 25-minute grace covers it without softening the alarm during a real failure.

I want to give my night manager view-only access.

That's a Team-tier feature. For now, the magic-link login is per email; if you want to share an account, the night manager logs in with the same email as you. We are aware that this is not ideal; the Team tier ships in Q3 2026 with per-user roles.

Can the report include photos?

A photo per device can be uploaded to the device's page (a sensor- location reference photo). The monthly PDF includes the photo on the device's per-device page. We do not support per-event photo attachments (e.g. "operator took a photo of the broken seal that caused the alarm"); that is on the roadmap.

What is "acknowledgement"?

When an alarm fires, the dashboard prompts the operator to add a short note: "What happened, what did you do." The note is recorded in the audit trail. Inspectors look for these — a clean log with no acknowledged events looks fine; a log with three alarms and three sensible notes ("door propped open during delivery, closed within 10 min, no temperature breach inside food") looks even better. It shows the system is read, not just installed.

My fridge is in a basement with no WiFi.

Three options:

1. WiFi extender. Cheapest. Works for most cases.
2. Powerline ethernet adapter to a small AP in the basement.
3. LoRaWAN sensor (Efento NS-T) plus a gateway upstairs; LoRaWAN penetrates concrete walls much better than WiFi.

We have customers using each of the three. Pick on bill-of-materials, not on opinion.