VisionDesign rev A, 28 Oct 2026: smart walk-in door frame that runs the cold room (9 calls, 6 alone, 3 assist; EPA leak-repair record added 30 Oct), call lights, tone, display, ATECC608 and tamper switch inside; 11 camera and radar views checked in the CAD; not built

ChillOne

IEMI's one product for a walk-in cooler: the walk-in's own door frame, made smart

The door frame already round every walk-in cooler or freezer door, at the same size, cut-out and 120 V feed, keeps the signed food and vaccine temperature log with now, min and max at eye height, times the door, alarms on power loss over LTE-M, calls an iced coil or a stuck defrost, warm product, product or ice on the floor and a person still inside after the door closes, and shows the shelves.

Who buys it: Owners and kitchen managers of restaurants, school and care-home kitchens, small grocers, pharmacies and clinics with one to three walk-ins, sold and fitted by their refrigeration contractor.
Why it pays: $690 + $29/month per walk-in instead of about $797 + $90/month for CoolerCheck, ColdChain Guard, ShelfScan and a plain thermometer and light switch frame part bought separately (est.).
Target price: $690 per walk-in (replaces its door frame) + $29/month cold room app with LTE-M (target)
First-minute wow: 02:14 on a Saturday: the power drops and the kitchen Wi-Fi with it. The door frame texts the owner over LTE-M on its backup cell, and the signed log shows the inspector exactly how warm the box got and for how long.

See the CAD design Concept page

ChillOne concept: the idea and where each part goes — The concept. The CAD design is below, under Printable CAD.

What the research found

And how this design answers it

Rev A (28 Oct 2026): the food, cold chain and pharma flagship is the walk-in's own door frame. Header: Raspberry Pi Zero 2 W brain, Camera Module 3 Wide (35 degrees down into the room), MLX90640 heat camera (level, to the coil and shelves), LD2410C radar, SHT45, DS18B20 probe in a glycol vial, Walter LTE-M, ATECC608, D2F-01 tamper switch, piezo and two NeoPixel call lights; hinge jamb: IRM-05-5 on the frame's 120 V feed, PowerBoost 1000C and LiPo backup, 2.13 in e-paper; strike jamb: door contact
Makes the cold room's calls itself: door open, temperature out of band, power lost, iced coil or stuck defrost, warm product or floor items and a person still inside alone; compressor trouble and low shelves go to a person; unsure means 'check'
Legal on the walk-in: 10 CFR 431.306 door closer, strip curtain and light kept, FDA Food Code 4-204.112 thermometer and the CDC vaccine data logger rules met, 864 x 1930 mm opening (ADA 32 in) and the 4 in wall depth checked in the CAD
Privacy first: no face recognition, shelf stills and clips around calls only (30 days), staff notice label
Market and rules check (30 Oct 2026): EPA's leak-repair rule (40 CFR 84.106) has applied since 1 January 2026 to refrigeration with 15 lb or more of HFC, with a leak rate worked out at every top-up, repairs within 30 days above 20 % and three years of records; ChillOne adds a signed refrigerant record (the technician enters each top-up, the frame works out the leak rate and counts down the 30 days, with the coil and air curve from before); FSMA 204 traceability not enforced before 20 July 2028; the $438.49 Kitchen Brains Modularm 75LC walk-in alarm added to the competitors; no new part

Use case

A 60-seat restaurant with one walk-in cooler and one walk-in freezer

OwnerKitchen managerRefrigeration contractorHealth inspector

01Trigger: a door propped during a delivery, a stuck defrost, a power cut at night, a case left on the floor
02Detect: door contact, radar, buffered probe, air sensor, room camera and heat camera inside the frame
03Act: the frame's own amber, red, blue or white call light with a tone; SMS over LTE-M when the power is off
04Log: one signed temperature and event log per walk-in, opened by the inspector with a QR code

Outcome: No paper log, no surprise warm box in the morning, a daytime contractor visit instead of lost stock, and nobody left inside

How it works

Architecture

01
Sense: a door contact, a radar, a buffered probe, an air sensor, a room camera and a heat camera inside the frame
02
Decide: door, temperature, power, defrost, floor and person models on the Pi Zero 2 W; 'check' below the line
03
Act: the frame's own call lights, a tone and the e-paper
04
Tell: one signed log to the cold room app over Wi-Fi or LTE-M

Hardware

Real parts, buyable today

Bill of materials: $429 of parts per door frame at qty 1 (prices checked 29 Oct 2026; frame tubes est.); replaces the walk-in's door frame.

Block	Part	Why this part
Brain	Raspberry Pi Zero 2 W	Runs every cold room model and the calls
See	Raspberry Pi Camera Module 3 Wide + Adafruit 4469 MLX90640 + HLK-LD2410C	Shelves and floor; the coil and warm product; a person in the dark
Temperature	Adafruit 381 DS18B20 in glycol + Adafruit 5665 SHT45	The food and vaccine log; door, defrost and compressor curves
Calls	Waveshare 2.13 in e-paper, 2 x NeoPixel Stick 8, Adafruit 160, Adafruit 375	Now, min and max; call lights and tone; the door contact
Security, power and uplink	ATECC608, Omron D2F-01, Mean Well IRM-05-5, PowerBoost 1000C, LiPo, DPTechnics Walter	Signed calls, tamper log, alarms on LTE-M with the power off

Mechanical

Printable CAD

3 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

Open risks we are working on

Condensation on the inside windows when the door opens; relies on the frame's heater wire and needs tests in a freezer
The probe vial at the door reads the warmest part of the box; a vaccine user may want a second probe at the middle shelf (planned as a paired option)
Shelf rows behind other boxes cannot be seen; shelf reports are a guide, not a count
LTE-M coverage inside steel buildings varies; Wi-Fi is the first path
Listing (UL 471 / NSF 7), radio and per-unit calibration are still to be done

Design stage only: nothing on this page is for sale. Specifications and prices are targets.