Hardware Shopping List¶
ChillCheck uses off-the-shelf hardware that you buy yourself. There is no proprietary equipment to purchase from us.
Required hardware¶
Raspberry Pi 4 (2 GB or 4 GB RAM)¶
The hub that runs on your premises. The 2 GB model is sufficient for most sites.
- Raspberry Pi 4 Model B (2 GB) — approximately £35–45
- Available from The Pi Hut, Pimoroni, or Amazon UK
You will also need:
| Item | Notes | Approx. cost |
|---|---|---|
| MicroSD card (32 GB+, Class 10) | Samsung Endurance or SanDisk Endurance recommended for 24/7 use | £8–12 |
| USB-C power supply (5V 3A) | Official Raspberry Pi PSU preferred | £8 |
| Ethernet cable | Any standard Cat5e or Cat6 | £3–5 |
| Micro HDMI cable + keyboard | For initial setup only — not needed permanently | One-off |
No case required
The Pi does not need a case for operation, but a basic enclosure helps protect it from dust and accidental damage in a kitchen environment.
ZigBee USB dongle¶
Bridges your sensors to the Pi over the ZigBee radio protocol.
- SONOFF Zigbee 3.0 USB Dongle Plus (ZBDongle-E) — approximately £15–20
- Available from SONOFF official store, Amazon UK, or AliExpress
Use the ZBDongle-E, not the ZBDongle-P
ChillCheck is tested and configured for the ZBDongle-E (EFR32MG21 chipset). The older ZBDongle-P uses a different chipset and is not supported.
Temperature sensors¶
- SONOFF SNZB-02LD — approximately £10–14 each
- Available from SONOFF official store or Amazon UK
Buy one sensor per cabinet (fridge, freezer, or walk-in) you want to monitor. A typical small food business needs 3–8 sensors.
Sensor specs: - Temperature range: -20°C to +60°C - Accuracy: ±0.5°C - Battery: CR2450 (replaceable), approximately 2-year life - Wireless: ZigBee 3.0, range approximately 10–30 m (line of sight) - IP rating: IP20 (indoor use, not waterproof)
Walk-in chillers
Place the sensor on a shelf mid-height, away from the evaporator unit and the door. Temperature near the evaporator or door can vary significantly from the actual cabinet temperature.
UPS (uninterruptible power supply)¶
A small UPS keeps the hub running during brief power outages and protects against data loss from sudden power cuts.
- APC Back-UPS 700VA (BX700U-GR or similar) — approximately £60–80
- Or a Pi-specific UPS HAT, e.g. PiJuice HAT (requires solderless header)
Any UPS with a standard UK socket that provides runtime of 15–30 minutes is suitable.
Optional: 4G failover dongle¶
If your site's internet connection is unreliable, a 4G USB dongle provides an automatic backup uplink. When broadband drops the Pi switches over silently; when it recovers, broadband takes priority again. No manual intervention needed.
ChillCheck uses less than 200 MB/month at typical sensor density, so even a basic data SIM is ample.
Choosing a dongle — HiLink mode is essential
4G USB dongles come in two modes:
| Mode | How it appears to the Pi | Works automatically? |
|---|---|---|
| HiLink (preferred) | USB ethernet adapter — just plug in | Yes — Pi OS sees it as a network interface immediately |
| Stick / PPP mode | Serial modem — requires ppp or ModemManager setup | No — requires additional manual configuration |
Buy a HiLink-mode dongle. The ones listed below have been confirmed to work in HiLink mode on Pi OS Bookworm without any additional setup.
Confirmed working (UK):
| Dongle | Price | Notes |
|---|---|---|
| Huawei E3372h-320 | ~£25–35 | Most common. Look for the "h" suffix — confirms HiLink mode. Available unlocked on Amazon UK and eBay. |
| Huawei E3372s-153 | ~£20–30 | Older HiLink variant; equally plug-and-play. |
Avoid E3372t and E3372e variants
The t and e variants use "stick mode" (PPP/serial) rather than HiLink. They require manual setup and do not benefit from the automatic failover that ChillCheck's setup script configures. Check the suffix carefully before buying.
SIM card — UK carrier recommendations:
Any standard UK data SIM works. The dongle needs to be unlocked (or bought pre-unlocked for the carrier you choose).
| Carrier | Coverage | Notes |
|---|---|---|
| Three UK | Good UK-wide, strong indoors | Affordable data-only SIMs; 1 GB/month SIM plans available |
| SMARTY | Three network | Cheap, no-contract; same coverage as Three |
| EE | Widest UK coverage | More expensive but best rural coverage |
| Vodafone | Good UK coverage | Business data SIMs available; useful if you already have a Vodafone account |
A 1 GB/month data-only SIM is sufficient. ChillCheck does not require a voice or SMS allowance.
For full configuration details, see 4G failover setup.
Total cost¶
| Scenario | Approx. cost |
|---|---|
| Single site, 4 cabinets, no UPS | £110–140 |
| Single site, 4 cabinets, with UPS | £170–220 |
| Single site, 8 cabinets, with UPS | £220–290 |
Costs are one-off hardware purchases. ChillCheck subscription is separate (from £5/month).