ColdRoom
Walk-in cooler alarm, temperature record and shelf photos in one hub
Does the job of CoolerCheck (door left open, defrost and compressor trouble, power loss), ColdChain Guard (product temperature record with a QR link, delivery record, LTE-M backup) and ShelfScan (empty and low shelf rows with a photo) from one hub with one brain.
- Who buys it
- Independent restaurants, school and care-home kitchens and small grocers with 1–3 walk-in coolers, sold and fitted by their refrigeration contractor (CoolerCheck channel).
- Why it pays
- $299 + $29/mo per walk-in against $697 + $90/mo for our three products bought separately; replaces the paper cold-holding log and the walk in to check stock before ordering (est.).
- Target price
- $299 per walk-in + $29/month (target)
- First-minute wow
- The contractor fits one white box above the cooler door in 30 minutes; the manager's phone shows the product temperature, the door, a fault card, today's record with a QR link for the inspector, and a photo of the shelf that just ran empty.
What the research found
And how this design answers it
- Three single-job products, three apps → one hub, one brain (XIAO ESP32S3 Sense), one backup and one app
- Inspectors ask for the cold-holding record (FDA Food Code 3-501.16, 5 °C) → product probe and a 12-month record behind a QR label on the door frame
- Wi-Fi does not get out of a steel walk-in → antenna plate outside the door with LTE and Wi-Fi flex antennas, coax under the gasket
- A power cut takes the router down too → LTE-M modem and 2 x L91 backup keep alerts going for weeks (est.)
- Staff walk in to see what is low before ordering → one shelf photo every 30 minutes, empty rows as tasks
- Dropped: CoolerCheck LoRa gateway and CT node (optional add-on), ColdChain truck GNSS and BLE tag, ShelfScan Pi hub and battery cameras
Use case
Door left ajar after the morning delivery
Kitchen managerPrep cookRefrigeration contractor
- 01Trigger: the delivery driver leaves the walk-in door resting on a crate
- 02Detection: the reed switch shows open for 5 minutes; the air warms and the glycol probe starts to follow
- 03Alert: amber light and a push to the manager; after 15 minutes an SMS to the contractor
- 04Action: the cook shuts the door; the record shows the product stayed under 5 °C and the shelf photo shows the delivery put away
Outcome: No stock thrown out, and the record for the inspector shows the door event and the recovery
How it works
Architecture
- 01
Sense: air and product DS18B20 probes, door reed, SHT45, OV3660 shelf camera
- 02
Decide: the ESP32-S3 runs the cooler rules, keeps the record and scores shelf zones
- 03
Send: Wi-Fi MQTT, or LTE-M through the nRF9151 when Wi-Fi or mains is down
- 04
Tell: push and SMS to the manager and contractor, QR record for the inspector, shelf tasks
Hardware
Real parts, buyable today
Bill of materials: about $119 per walk-in at qty 1 (est.).
| Block | Part | Why this part |
|---|---|---|
| Brain + camera | Seeed XIAO ESP32S3 Sense (OV3660) | Runs all three jobs and sees the shelves |
| Backup radio | Nordic nRF9151 LTE-M modem | Alerts get out with the router down |
| Temperature | 2 x DS18B20 probes (air, glycol bottle) | Air for faults, product for the record |
| Door | Adafruit 375 reed switch | Door open time and delivery events |
| Power | 5 V USB-C adapter + 2 x Energizer L91 | Weeks of backup, rated to −40 °C |
Mechanical
Printable CAD
8 parts, generated from code and checked as closed solids. Pick a part to inspect it, or download the STL files to print.
Loading the CAD…
Real CAD · drag to rotate · scroll to zoomReal CAD · swipe sideways
Bought hardware fitted inside this part (checked in the CAD: nothing collides with the plastic)
- Hub basehub-base.stl · PETG
- Hub lid with camera windowhub-lid.stl · PETG
- Wall bracketwall-bracket.stl · PETG
- Antenna plate with QR record labelantenna-plate.stl · PETG
- Door-seal passseal-pass.stl · TPU
- Air probe clip (CoolerCheck)air-probe-clip.stl · TPU
- Glycol bottle holder (CoolerCheck)glycol-bottle-holder.stl · TPU
- Door magnet bracket (CoolerCheck)door-magnet-bracket.stl · PETG
Open risks we are working on
- Radio out of a steel box depends on the coax under the gasket; a cut coax stops both radios
- Window fog when the door opens; anti-fog disc and weep hole still to test
- Shelf zones on an ESP32-S3 misread when stock is moved; no SKU recognition claimed
- Staff privacy: photos only with the door shut, person shots deleted, notice on the lid; rules differ by country
- The record helps show monitoring; it does not make a kitchen compliant
- Coolers only: in a freezer the window frosts
Design stage only: nothing on this page is for sale. Specifications and prices are targets.