What size, and what it costs.
A chiller that is forty per cent undersized does not hold the reservoir forty per cent less well. It holds it at 27 °C all summer, which is not a degraded outcome — it is root disease. So the sizing is arithmetic from stated assumptions rather than a rule of thumb, and every assumption is on the page where you can disagree with it.
- Reservoir
- 200 L
- Circulation
- 600 L/h
- Peak delivery
- 26 L/h
- Daily water
- 48 L
- Chiller
- 161 W ≈ 0.22 HP
- Aeration
- 1.7 L/min
Of that cooling load, 99 W leaks in through the tank wall and 30 W is the circulation pump putting its own power straight into the water — which is not a rounding error and is the figure most often left out. It pulls the tank down one degree in about 86.7 minutes, which is what decides whether it can recover from an afternoon.
The bill of materials
One to five rooms, several zones. Raspberry Pi 5 running an-hydrod. 2 to 15 ESP32-S3. I²C sensors, RS-485 to industrial probes, MQTT smart plugs.
Survives a power cut, a router reboot and a monsoon week without anybody driving out to it.
| Item | Qty | Each | Line |
|---|---|---|---|
| Raspberry Pi 5, 8 GB, with SSD and case SD cards fail. Use an SSD |
1 | ₹9,500 | ₹9,500 |
| UPS for the hub and the network | 1 | ₹4,500 | ₹4,500 |
| ESP32-S3 node, built as the Bench list Per node, complete |
4 | ₹11,350 | ₹45,400 |
| RS-485 EC/pH/temperature transmitter Industrial, and the redundancy that gives dosing authority |
2 | ₹7,800 | ₹15,600 |
| Substrate water content / EC sensor Imported. Without this there is no crop steering |
2 | ₹12,500 | ₹25,000 |
| PAR sensor Imported. Turns clock irrigation into light irrigation |
1 | ₹6,500 | ₹6,500 |
| Dissolved oxygen probe Imported |
1 | ₹9,500 | ₹9,500 |
| Peristaltic dosing pumps, 24 V pH-down, pH-up, A and B |
4 | ₹2,600 | ₹10,400 |
| Reservoir chiller, 1/4 HP The item most often skipped and most often the reason a summer crop fails |
1 | ₹34,000 | ₹34,000 |
| Managed switch and outdoor-rated cabling | 1 | ₹6,000 | ₹6,000 |
| Distribution board, RCD, contactors To be signed off by a licensed electrical engineer |
1 | ₹8,500 | ₹8,500 |
| Total, ex-GST | ₹174,900 | ||
Mid-2026 street prices for the Indian market. They will be wrong within a year and they are here anyway, because a bill of materials with no numbers in it is one nobody can make a decision from. Anything imported carries customs and freight that are frequently more than the part.
Electrical safety is not a line item. The RCD is in the list because it is mandatory, and the panel work at the Farm and Commercial tiers is engineered rather than assembled. Have the mains section reviewed by a licensed electrical engineer before anything is sold or installed.