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ETC Tube
ETC Tube (Evacuated Tube Collector) for Solar Water Heaters
An ETC tube is a vacuum glass tube that captures sunlight and turns it into heat for water heating. The vacuum stops heat loss, so it works well even in cool weather. Ashirwad Solar supplies ETC tubes in four sizes, from 47 x 1500 mm to 58 x 2100 mm, and fits them in our solar water heaters.
An evacuated-tube collector contains several rows of glass tubes connected to a header pipe. Each tube has the air removed from it (evacuated) to eliminate heat loss through convection and conduction. Inside the glass tube, a flat or curved aluminium or copper fin is attached to a metal pipe. The fin is covered with a selective coating that transfers heat to the fluid that is circulating through the pipe.
Looking for ETC tube manufacturers in India? See our dedicated page on ETC tube manufacturers in India, or send us your size and quantity below.
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Types of Evacuated Tube Collectors
There are two main types of evacuated tube collectors :
- Direct-flow evacuated-tube collectors.
- Heat-pipe evacuated-tube collectors.
How an ETC Tube Works
- Sunlight passes through the outer glass and reaches the coated surface inside.
- The coating absorbs the light and turns it into heat.
- The heat moves into the water or fluid.
- The vacuum blocks heat from escaping, so the water stays hot.
ETC Tube Sizes Available
Sizes are given as diameter x length in millimetres. Choose the size that matches your collector or water heater model.
| Sr.No. | Available Sizes |
|---|---|
| 1. | 47x 1500 |
| 2. | 47x 1800 |
| 3. | 58x 1800 |
| 4. | 58x 2100 |
In our water heaters, 58 x 1800 mm tubes are used in the 100, 150, 200, 300 and 1000 LPD models, and 58 x 2100 mm tubes in the 500 LPD model.
Why Choose ETC Tubes?
- Less heat loss: the vacuum removes loss through convection and conduction.
- Good in cooler weather: they keep heating when air is cold or sunlight is low.
- Easy to replace: if one tube is damaged, you replace that tube only.
- Scalable: add more tubes for bigger hot water needs.
ETC vs Flat Plate Collectors
| Point | ETC tube | Flat plate collector |
|---|---|---|
| Design | Vacuum glass tubes | Insulated flat panel |
| Heat loss | Lower | Higher in cold weather |
| Best for | Cooler weather, low sunlight | Warm climates |
| Repair | Replace single tubes | Replace panel |
Where ETC Tubes Are Used
- Homes and apartments: see our GI/MS tank water heater and SS tank water heater, both built with ETC tubes.
- Hotels, hospitals and hostels: steady hot water for rooms, wards and kitchens. A commercial solar system can also cut the building's power bill.
- Factories and canteens: hot water for cleaning and washing. Explore industrial solar solutions.
Go Solar Beyond Hot Water
If you already use solar for hot water, a rooftop solar system can cover your electricity too, and our team handles solar panel installation services from survey to commissioning.
Why Buy From Ashirwad Solar
We started in 2007 as a fabricator of solar water heater components and now make renewable energy products at our factory unit in Gogalwadi, Haveli, Pune. Buying direct from the maker means clear size advice, fair pricing and quick service.
ETC Tube FAQs
What is an ETC tube?
An ETC (evacuated tube collector) tube is a glass tube with the air removed from it. The vacuum stops heat escaping, so the tube can heat water efficiently, even in cool weather. Several tubes together form the collector of a solar water heater.
How does an evacuated tube collector work?
Sunlight passes through the glass and is absorbed by a coated surface inside the tube. The heat is passed to the water or fluid, and the vacuum keeps it from leaking out through convection and conduction.
What ETC tube sizes are available?
We offer four sizes: 47 x 1500 mm, 47 x 1800 mm, 58 x 1800 mm and 58 x 2100 mm. The first number is the tube diameter and the second is its length.
How many tubes does my solar water heater need?
In our GI/MS tank systems, a 100 LPD heater uses 10 tubes, 150 LPD uses 15, 200 LPD uses 20, 300 LPD uses 30, 500 LPD uses 32 longer tubes and 1000 LPD uses 100. Contact us for the exact count for your model.
What is the difference between ETC and flat plate collectors?
A flat plate collector heats water in an insulated flat panel. An ETC uses vacuum tubes that lose less heat, so it keeps working well in cooler weather and low sunlight.
Can I use ETC tubes with hard or borewell water?
Yes, but the tank matters too. For hard, salty or borewell water we suggest our SS tank water heater, which has a rust-proof stainless steel tank.
Get a Quote for ETC Tubes
Tell us the tube size, quantity and your city. We will reply with a written quote. Call +91 99224 26936 or use the enquiry form.
