Your old temperature monitoring system is dying: revive it or replace it?

You bought or took over a site and there is a box with a display on the wall that nobody has the password for. Or your own temperature monitoring system is wearing out after years and the supplier no longer picks up the phone. The question is always the same: repair it, or replace it? The answer depends on five things. The most important one is not the electronics. It is the probes and the paperwork that goes with them.

The short answer

Reviving an old system is worth it if service is still available, it can export and archive records, it sends alarms off-site and you can produce a valid calibration certificate from an accredited laboratory for its probes. If even one of these is missing, a repair gives you a working display, not records that hold up at an inspection.

Five questions that decide

1. Is there still service and spare parts? If the supplier is gone or the installer no longer exists, every fault means hunting for someone who understands somebody else's equipment.
2. Can the system hand over records? Inspectors want a continuous record for a period, ideally as a PDF. If the data only lives on a display or on an old office PC, you effectively have no record.
3. Where do alarms go? A siren in an empty building at 2 a.m. wakes nobody. An alarm should reach your phone, e-mail or SMS.
4. Do the probes have calibration documents? This is where revival most often fails. More below.
5. Who will look after it for the next years? Calibrations, probe replacements, updates. If the answer is "we will", count it as extra work.

Why the probes are the catch

In Slovakia, Decree 533/2007 requires temperatures in refrigeration and freezing equipment to be verified with a mandatorily calibrated instrument, and the Metrology Act 157/2018 (§ 17) says such an instrument may only be calibrated by the national metrology institute or an accredited calibration laboratory. Food safety inspectors elsewhere expect the same thing in practice: an instrument with a calibration you can point to. An old system often still measures reliably, but nobody has the papers for its probes any more. The probes have been built into the rooms for years, nobody knows when they were last calibrated, and the documents were lost when the owner changed.

Old probes can be calibrated too. It means removing them, sending them to a laboratory and running without measurement in the meantime. For individual pieces the cost runs to tens of euros per probe, and it repeats at every recalibration. Meanwhile the Slovak metrology inspectorate has been targeting chilled and frozen storage since 2023 and finds violations at two thirds of the sites it checks. The most common finding is a missing calibration document and no instrument register.

The old system does not have to be scrapped

In cold stores and production the original system is often part of the refrigeration control: controllers switch compressors and defrost based on their own sensors. Let that keep running. Proving temperatures to an inspector is a different job and can be solved separately. Independent probes with calibration certificates go next to the original ones, the refrigeration is not touched and nothing is wired together. A bonus: if the controller's sensor drifts over time, the independent measurement shows it.

When replacement is the clear choice

• You took over the site without documentation, passwords or calibration certificates.
• The system runs on a computer or software nobody supports any more.
• Records cannot be printed or archived.
• An alarm about a failure never reaches you off-site.
• A repair would cost about as much as a new solution and you would still handle calibrations separately.

What replacement looks like in practice

With TempeStorm every monitoring point gets a new probe with a calibration certificate from an accredited laboratory. The certificate and the regular exchange of probes for freshly calibrated ones are included in the service. The instrument register and calibration validity are kept by the system itself. Records are created continuously, alarms reach your phone, e-mail and SMS, and the HACCP PDF protocol is one click away. Installation does not touch your equipment and usually takes one day. We describe how probe calibration works in a separate article.

You can buy the devices or rent them with no upfront investment. To see what it would cost for your number of monitoring points, use the pricing configurator. The price shows instantly.

Sources: Slovak Act 157/2018 on metrology (§ 17, § 55), Decree 533/2007 of the Slovak Ministry of Health, annual reports of ÚNMS SR.