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Hot Water Cylinders, Hot Water Heaters - OSO Hotwater UK

Hot water cylinders - the most efficient in the world

OSO Hotwater is the world’s largest manufacturer of stainless steel unvented hot water cylinders

Manufactured in Norway since 1932, OSO cylinders have won countless awards for quality and sustainable production. 

Unvented hotwater cylinders connect directly to the water main and provide high pressure hot water to showers and taps throughout the building


Register your cylinder for warranty and book for service and or repair with OSO’s Approved Service and Warranty team.

Joining OSO Approved Certified Installer gives you access to approved spares, training, and work revenue opportunities.

OSO Partner offers better rewards, more support, promotions, training and exclusive events.

At OSO Spares you can buy all current and historic official OSO cylinders and spare parts.

INCOTEC™ ultra-alloy heating elements give OSO products maximum durability in calcareous water.
Most experience
OSO was the first producer of stainless hot water heaters in Europe. We have more than 50 years of experience with 4 million heaters.
A sustainable company
OSO has won several awards for our working environment.

Of particular importance has been the National Honorary Award “Glassbjørnen” (the Glass Bear) for unique environment efforts through 30 years, the “SCANVAC” award for the Best Environmental Company in Scandinavia and the “Best environment and Energy Efficiency product” for introducing foam insulated storage tanks.
EVERLAST™ stainless steel in combination with OSO ULTRAWELD™ system gives the OSO products a leading corrosion resistance on the market.
OSO Hotwater AS is since 2015 the most robotized manufacturing company in Norway.
The Family business
Three generations of Braathen have lived with a pioneering spirit on product innovations, now featuring integrated solutions, ground-breaking material technology and added value for customers.
The green shift
OSO is a preferred supplier to many of the best-known brands in the heating industry, delivering products throughout Europe - making the industry a little greener piece by piece.
Well isolated
NANOPUR™ isolation gives OSO heaters and cylinders a market-leading energy efficiency. Save 500 kWh / year with a new 200 liter heater!
A Norwegian Industrial Adventure
With minimal resources the first OSO heater was created in 1932. Within 8 years 100 were employed, and this was the beginning of a Norwegian industrial adventure.


Throughout 60 years we have perfected the stainless steel heater. The combination of material choice, robotized production and intelligent solutions gives the OSO products unbeatable lifetime.

Energy efficiency

OSO heaters have the lowest heat loss on the market, and are designed to give maximum performance. This gives our products the lowest power consumption and a unique lifespan economy for our customers.


50 years of efforts and investments to unite people, environment and industry, and for this given several awards. In three generations our objective has been the same:

Protect Our Beautiful Planet!



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Innovation timeline