01How ETC works
A vacuum between the concentric glass layers reduces heat loss while the selective inner coating absorbs sunlight. In a direct thermosiphon system, warmed water rises to the storage tank and cooler water returns to the tubes. The selected SSmart standard ETC catalogue series uses 1 evacuated tube per 10 LPD: 100 LPD has 10 tubes, 150 LPD has 15, 200 LPD has 20, 300 LPD has 30 and 500 LPD has 50. Final supply must still match the approved tube length, diameter, coating, tank loss and product data sheet.
02Budget and selection
ETC is often the lower-cost domestic option. Compare inner-tank material and thickness, insulation, outer cladding, frame corrosion protection, tube standard, sacrificial anode where used, pressure rating, valve set and local service. Hard water can scale direct-contact surfaces, so include periodic inspection or treatment.
03Tube replacement
Isolate cold feed and backup power, allow the system to cool, drain to a safe level, remove the broken tube with gloves and eye protection, clean the socket and replace seals only with the approved size. Do not work on a hot, pressurised or inaccessible roof system. After replacement, fill slowly and check for leaks and air locks.
04Patna water check
Groundwater and municipal supply quality vary by locality and season. Test hardness, total dissolved solids, chlorides and visible sediment where tank life or scaling is a concern. Select SS grade, glass-lined storage, anode and cleaning interval from evidence rather than a city-wide assumption.
Planning table
Compare before requesting a quote
| Capacity | ETC tubes | Planning price | Typical users | Service focus |
|---|
| 100 LPD | 10 | ₹28,000–₹38,000 | 2–3 | Tube and tank check |
| 150 LPD | 15 | ₹33,000–₹46,000 | 3–5 | Scale inspection |
| 200 LPD | 20 | ₹40,000–₹58,000 | 4–7 | Anode/tank protection |
| 300 LPD | 30 | ₹55,000–₹80,000 | 7–10 | Distribution and peak load |
| 500 LPD | 50 | Project quotation | Commercial | Hydraulics and peak-load study |
Indicative ranges are planning aids for Patna, not quotations. Capacity, pressure, tank metallurgy, roof work, piping, controls, GST, transport, electrical work and warranty can change the signed price.
