1980

Kurt Karlsson developed a groundwater heat pump with an evaporator PEL tube and integrated capillary that was patented in seventeen countries.
The evaporator construction made it possible to sub cool water and take 10W/l by freezing water to ice.
The product is still manufactured and installed in houses and industries.

1982

Kurt Karlsson developed a tube heat exchanger, the construction was made of 600 m PEL tube and two evaporator PEL tubes.
It became a combined air- and groundwater heat pump. Many installations are still running.

1983

The Hässleholm model was an air-, drinking water heat pump installed in Hässleholm, the Community sold the water to the heat-pumps.

1987

The PEL tube evaporator was replaced by a direct expansion air fan evaporator with an automatic defroster, this made it easier to install.

1991

Kurt Karlsson develops the Ice-Stick, as a replacement for the air fan evaporator.
Kurt had succeeded in making a heat pump as simple as a chest freezer. The effect was 48 times larger then a normal freezer.
The Ice-Stick consists of only one moving part the compressor, no pumps, no air fan, no losses in defrosting and no oil heater.
The Ice-Stick’s evaporator surface is enlarged 32 times compared to a normal 22 mm copper tube.

1997

The OM400i is sold as a small district heating system with two water tubes connect-able to the house heating system.
The Ice-Stick is tested at the factory and Gasol (propane) is applied, could the heat pump technology become easier.

The OM400i is sold together with a new control system that divides the heat in the house and preheats the boiler water by taking advantage of the radiators and floor heating as a sun collector. To make this possible all thermostats have to be fully open the whole year.

1999

Hundreds of OM400i combined with the new control system are operating. I some cases the ground water installation was replaced with an
Ice-Stick, the energy saving was the same without the environmental disturbance.

2004

The Ice-Stick is released in three new models, 48X, 61X and 81X. X is the number of chest freezers comparable to the size of the Ice-Stick.
The breaking news is 61X, an Ice-Stick that can be combined with a 30-60 meter copper tube in the earth.

The combination makes it possible for the heat pump to use the earth when the temperature goes below minus Celsius,
no pump is used the simplicity of the Ice-Stick is kept.