Once you see an evacuated tube in action, you will truly understand how they can smash your hot water heating bill.
Are evacuated tubes the right choice for you?
Key benefits of Evacuated tubes.
- 92% efficient.
- No moving parts. Made from Glass and copper there is little or no maintenance needed. Ever!
- Passive tracking. The round shape of the glass means the sun will always be hitting the tube straight maximising the solar gain.
- Pitching frame included. If your roof is flat, there is no need to purchase extra frame parts. they are all supplied.
- Stainless steel frame. made from Structural stainless steel and powder coated for extra protection.
- Multiple sizes. 20, 24 or 30 Evacuated tube manifolds available.
- 15 Year warranty.
Designed in Australia.
Evacuated tubes were invented to minimize heat loss in solar hot water heating typically experienced with Flat plate solar collectors. The construction of a flat plate collector uses a piece of glass to allow the heat into the collector but struggles to stop heat leaving the collector as glass is not a good insulator.
Evacuated tubes use 2 layers of glass with a vacuum in between the 2 layers. The outer glass is made of borosilicate glass which is very pure and does not contain any metal or materials that can become hot. The glass has very low thermal conductivity meaning it does not get hot. All the heat in the form of radiation that passes through the glass, does not get absorbed by the outer glass and is allowed to pass through it to the inner glass. The inner glass has 3 coatings of heat absorption and transfer material that takes the radiation and becomes hot.
Capture then store the heat.
The heat is then transferred using conduction to the water or liquid that is being heated. Once the heat is in between the 2 layers of glass, the vacuum does not let it out as a vacuum is an amazing insulator. Sounds confusing? Well yes but the main points are the heat can get into the tube but not out again. This efficiency gives an evacuated tube an efficiency of above 92%. Meaning that 92% of the heat that hits the tube goes in, but does not come out again.
Try touching an evacuated tube on the outer glass that is in the sun, it will be almost exactly the same temperature as the air. PLEASE DO NOT TOUCH THE INNER GLASS! The inner glass can reach temperatures of over 250 Deg C in a matter of minutes. Yes, 250 Deg C! Even on a 15 Deg day with clear skies. The air temp does not affect the efficiency of the tube because of the vacuum. It’s all about the power of the sunlight.