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Stainless steel water tank has a kind of water tank called stainless steel heat preservation water tank. The stainless steel heat preservation water tank has an important function, is the heat preservation. The heat preservation effect of water tank depends on the thickness of insulation layer (foam layer). The thicker the insulation layer and the wider the coverage, the better the insulation effect. The stainless steel heat preservation water tank has 50 mm polyurethane foam between the inner and outer tank, which can effectively ensure that the water tank inside the stainless steel water tank can drop no more than 5 ℃ within 24 hours. With the stainless steel heat preservation water tank, even in the outdoor, the water will not freeze.