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ETC (Evacuated Tube Collector) uses double-walled borosilicate vacuum tubes. The vacuum gap eliminates heat loss — like a Thermos flask. It works in diffuse light, handles hard water up to 3000 PPM, and requires zero maintenance. It is the right choice for most homes in hard water regions worldwide.

FPC (Flat Plate Collector) uses copper riser pipes bonded to a selective-coating absorber plate under toughened glass. It can be configured for pressurised delivery, making it ideal for apartments, hotels, and multi-storey buildings on soft water (up to 200 PPM).

In summary: ETC for homes and hard water regions worldwide. FPC for pressurised commercial systems on soft water.

Diamond Glassline is a German-technology (Wendel make) porcelain glass lining fused onto the TATA Steelium CR steel inner tank at 850°C. The result is a permanently bonded, non-reactive glass surface that:

• Resists corrosion even in hard water up to 3000 PPM
• Prevents mineral scale and bacterial buildup — water stays clean and hygienic
• Acts as a natural thermal insulator, extending heat retention alongside the 50mm PUF layer

It is the same technology used in high-end European water heaters, offered in Kaldor systems without the premium price.

Kaldor ETC systems use natural thermosyphon circulation. Heated water in the tubes becomes less dense and rises through the connecting pipe into the storage tank above. Cooler water flows down from the tank to replace it — a continuous passive loop requiring no pump, no electricity, and no moving parts.

The only installation requirement is that the tank must sit higher than the collector — the standard rooftop configuration worldwide.

Three metallic layers — Aluminium, Copper, and Nickel (Al/Cu/Ni) — are deposited on the inner absorber tube. This achieves an absorptivity of 0.097 ± 0.02, meaning over 97% of incident solar radiation across the full spectrum is absorbed. Combined with the vacuum insulation, nearly all that energy goes into heating water rather than being lost to the environment.

Yes, partially. ETC tubes absorb diffuse UV radiation even on overcast days — on a typical monsoon day expect 40–60% of peak output. On heavily overcast days the electrical backup element activates automatically.

Kerala receives an annual average of 5.5 peak sun hours per day. Even accounting for the June–September monsoon months, solar water heating is highly economical here — the system saves energy for approximately 9–10 months of clear or partly sunny weather each year.

On a sunny day, outlet temperature reaches 70–90°C — always mix cold water before use. A thermostatic mixing valve is recommended for bathroom installations to prevent scalding.

The Diamond Glassline tank retains this temperature for 24–36 hours, so yesterday's afternoon sun provides hot water the following morning.

No, if you choose the right model. The ETC Diamond Glassline and ETC Prime Ceramic systems are engineered for hard water up to 3000 PPM. The non-reactive glass inner surface prevents scale adhesion, and ETC tubes keep water separate from the collector — only the tank contacts the water.

If your TDS is above 200 PPM — common in arid regions, many parts of Asia, Africa, and the Middle East — choose ETC Diamond Glassline. Avoid FPC and SS 304 Eco Deluxe models for hard water areas.

Allow 25–30 litres per person per day as a base guide:

• 2–3 people: 100 LPD
• 4–5 people: 200 LPD — most popular for family homes
• 6–8 people or large kitchen: 300 LPD
• Small guesthouse / homestay: 300–500 LPD
• Hotels, apartments, hospitals: 500–1000 LPD FPC array

Email enquiry@hydroluxsolutions.com for a personalised site assessment.

A 200 LPD system heating 150 litres by 40°C daily replaces approximately 80–100 kWh per month of electricity.

At typical electricity rates:
Savings vary by local electricity tariff. As an example, at ₹7/kWh a 200 LPD system saves approximately ₹560–700/month. In regions with higher electricity costs (such as the Middle East or Europe), savings are proportionally greater.

Over 10 years: substantial savings well above system cost, regardless of currency. Use our interactive Savings Calculator for a precise estimate.

For a typical 200 LPD system (pricing varies by region):

• Replacing electric geyser at ₹7/kWh → 3.5–4.5 years
• Replacing LPG geyser at ₹90/kg → 2.5–3.5 years
• Replacing diesel boiler → 2–3 years

After payback, you generate free hot water for another 15–20 years. Total 10-year net savings (after system cost) typically range from ₹35,000 to ₹70,000 depending on your current fuel.

Over 10 years, solar wins significantly:

Factor	Electric Geyser	Kaldor Solar
Purchase cost	₹8,000–15,000	₹18,000–35,000
Monthly running cost	₹600–900	₹0–80 (backup only)
10-year total cost	₹80,000–1,23,000	₹20,000–44,000
CO₂ per year	~850 kg	~85 kg (backup)
Maintenance	Element replacement every 3–5 yrs	Zero

A 200 LPD ETC system (20 tubes) needs approximately 2.5m × 1.5m of unshaded roof area plus space for the tank frame. The system installs on flat RCC roofs (most common in Kerala and Tamil Nadu), sloped tiled roofs, and terraces.

Ideal orientation: south-facing, 10–15° tilt from horizontal in the northern hemisphere (north-facing in the southern hemisphere). The Hydrolux Solutions team will assess your rooftop and recommend the optimal placement during the site visit.

A standard residential ETC installation is completed in 4–6 hours. Commercial FPC multi-collector arrays take 1–2 days. Hydrolux Solutions handles supply, delivery, installation, and commissioning worldwide. Email enquiry@hydroluxsolutions.com to schedule.

Yes. The Kaldor FPC Pressurised (PRD) system is designed for exactly this. A central collector array on the terrace provides pressurised hot water to all floors — widely used in housing societies and apartment complexes worldwide.

Hydrolux Solutions designs and installs centralised systems for housing societies, hospitals, hotels, and student hostels, with capacities up to 1000 LPD and beyond (multiple arrays in series).

ETC systems are designed for zero routine maintenance. Sealed vacuum tubes have no moving parts and the Diamond Glassline tank resists scale.

We recommend a once-a-year visual check: inspect the frame for rust, confirm tube connections are secure, and rinse dust off the tubes. In coastal areas, inspect powder coating on the frame annually for salt corrosion. This takes 15 minutes and requires no tools.

ETC tubes last 10–15 years. The tank and frame typically last 20–25 years. If a tube breaks or loses its vacuum (it will appear frosted or heat less effectively), it can be replaced individually — simply slide out the damaged tube and slide in a new one, without touching any plumbing.

Replacement tubes are available through Hydrolux Solutions. Contact enquiry@hydroluxsolutions.com for spare parts.

• ETC Diamond Glassline Ultimate — Best for most homes in hard water regions worldwide. Up to 3000 PPM. Most popular model across Kerala, Tamil Nadu, Karnataka.
• ETC Prime Ceramic — Fusion Bond Ceramic coating, similar hard water performance. Alternative to Diamond Glassline.
• ETC Eco Deluxe (SS 304-L) — Best for soft water areas and coastal regions needing salt resistance.
• FPC Non-Pressurised — Flat plate, gravity-fed. Soft water, larger collector area.
• FPC Pressurised (PRD) — Apartments, hotels, hospitals. Pressurised hot water delivery. Scales to 1000 LPD.

Kaldor systems are available exclusively through the authorized India distributor — Hydrolux Solutions.

• Email: enquiry@hydroluxsolutions.com
• HQ: Al Mamzar, Dubai, UAE

Hydrolux Solutions serves customers across the Middle East, South Asia, Southeast Asia, and beyond with supply, installation, and after-sales support.

Pricing varies by region, model, and installation requirements. Contact enquiry@hydroluxsolutions.com for a tailored quote including installation.

As a general guide: systems are available from entry-level 100 LPD residential units to 1000 LPD+ commercial FPC arrays. Pricing is provided on request based on your location and requirements.