Print this page as PDF

Send this page via e-mail

Add it to Favorites

Share OSO Hotwater on Twitter

Share OSO Hotwater on Facebook

Share this page with others

Product Advantages

Extremely low weight

Duplex is a stainless steel quality with a higher strength than traditional material qualities being used for water heaters. This makes it possible to reduce the material thickness significantly, and also reduces material consumption which corresponds perfectly with OSO’s environmental approach. For the installer it means easier handling during transportation and installation of the product.

Low heat loss

As one of the first water heater manufacturers, OSO introduced Polyurethane foam (PUR) as standard insulation for water heaters in 1996. Since then, more than 500.000 OSO water heaters with PUR insulation has been sold. OSO ECO Foam is a polyurethane based foam insulation based on environmentally friendly procedures. The insulation quality of PUR compared to traditional mineral wool or EPS is 25-30 % better. OSO ECO Foam entirely uses water power during the production process and in addition to the energy saving it is also environmentally friendly with a GWP of 1 and an ODP of 0. The foam insulation is 100 % recyclable and can be reused for a number of other products.


High efficiency

Our products incorporate many efficiency-improving details.

  • Highly efficient cold water diffusor to reduce turbulence
  • High heat transfer on the stainless steel heating coils made from Duplex material.
  • Electric heater angled downwards to heat the unit all the way to the bottom.
  • Higher temperature than most others, providing more hot water in a smaller unit.
  • OSO ECO Foam insulation provides very low heat loss.
Together, these key factors makes our products among the most efficient on the market.

High corrosion resistance

The combination of pioneering welding methods and Duplex steel provides OSO’s water heaters with a very high corrosion resistance. Duplex is equally good, and in most conditions, better than 316 steel grades and is the superior material quality being used for water heaters. Together with unique use of shielding / backing gas and optimal welding techniques, our products are suitable for aggressive water qualities with high levels of Chloride.

Environmentally correct procedures

The environment has been the center of attention for OSO’s production, product development and the life cycle of the products for 50 years. OSO first started its environmental efforts in the 1970’s. OSO’s production of approximately 150.000 water heaters per year does not lead to any environmentally harmful emissions, and the products are manufactured from more than 70 % recycled materials. OSO has been awarded a number of awards for its commitment to the environment, such as the “GRIP Glass bear honorary award” for outstanding, environmental work throughout 30 years (awarded by the Norwegian Department of Environment).



It is a matter of course that OSO’s products are operationally stable and safe for the end user. OSO’s products go through extensive testing during the product development process. Potential changes when it comes to material qualities or components are stress and performance tested in OSOs heat technological laboratory. Finished products are also stress-tested with 20.000 cycles – equaling the total life span of the product - before it is finally approved for sales.

All finished products undergo a pressure test with water equaling double the normal operating pressure and an electric OQC to ensure the quality of the heating element / thermostat and wires. Incoming quality controls are strict, and all critical to quality components are either sample tested or full batch tested before entering production. Laboratory inspections of steel and alloy qualities ensure that the materials at all times have the correct specifications.


In 1970, OSO was the first in the world to manufacture stainless steel water heaters. Since then, more than 3 million water heaters have been manufactured and has shown exceptional durability and lifetime economy. Worldwide, no one has manufactured more stainless steel water heaters than OSO.

OSO’s goal is that each and every development shall lead to an improvement for the end user. Both successful and failed development projects, continuous customer satisfaction surveys and feedback form the basis of our experience. OSO’s motto, “each and every claim shall lead to future sales”, is characteristic for our handling of product feedback – both positive and negative.