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
Multiple rooms and zones, mixed crops. Industrial mini-PC or a VM, with an optional warm standby. 15 or more, plus third-party PLCs. Modbus TCP and RTU, BACnet/IP to the HVAC, 4–20 mA transmitters, LoRaWAN outdoors.
Traceability reports somebody can hand to an auditor, and an audit log that says who changed a setpoint.
| Item | Qty | Each | Line |
|---|---|---|---|
| Industrial fanless mini-PC, DIN mounted | 1 | ₹42,000 | ₹42,000 |
| Warm standby unit Optional, and cheaper than one lost week of a polyhouse |
1 | ₹42,000 | ₹42,000 |
| ESP32-S3 node, built as the Bench list Per node |
16 | ₹11,350 | ₹181,600 |
| RS-485 transmitters, EC/pH/temperature Two per dosing reservoir, and that is a rule not a preference |
8 | ₹7,800 | ₹62,400 |
| Substrate sensors Imported |
8 | ₹12,500 | ₹100,000 |
| 4–20 mA pressure transmitters | 4 | ₹4,200 | ₹16,800 |
| Industrial dosing pump controller | 2 | ₹28,000 | ₹56,000 |
| Reservoir chiller, 1 HP | 2 | ₹78,000 | ₹156,000 |
| Modbus TCP gateway | 2 | ₹9,000 | ₹18,000 |
| Panel build, RCDs, contactors, labelling Engineered and certified, not assembled |
1 | ₹65,000 | ₹65,000 |
| Total, ex-GST | ₹739,800 | ||
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.