It’s hot on the inside
Keeping the heat on the inside of a hot water system storage tank is a major aspect of saving energy and operating costs and polyurethane insulation systems are the best way of doing this. Polyurethane is formed through the reaction of two chemical liquids with the mixture then injected into a contained space. As the mixture is exposed to air, it expands to up to 10 times its liquid volume. In so doing it fills all of the contained space including the smallest of crevices. As the mixture dries it hardens to form a closed-cell structure that is a rigid and impermeable structure. Compared to fibreglass insulation that allows air to permeate, polyurethane is airtight. The resulting insulating barrier works at three levels: the gases trapped in the cells resist conductive heat losses; the air-tight structure prevents convective heat loss otherwise caused by the flow of warm air to the cooler surrounds; and condensation heat loss, normally caused as warm air is introduced to cold air, are avoided.
The hot water cylinders of all Envirosun storage tanks are encased within a polyurethane foam insulation system. The polyurethane mixture is pressure injected into the space between the cylinder and the external sheet metal casing.
The combination of metal and foam contributes to structural rigidity and is the basis of its excellent heat retention properties.