Should a hot water cylinder be raised off the concrete floor?

[Peter A]

Out hot water cylinder (unvented electric) is fitted in an upstairs cupboard, sitting directly on a concrete floor. I've been wondering if, despite the huge amount of insulation built into modern cylinders, sitting directly on concrete could be drawing away a lot of heat from the cylinder, making it much less efficient.

Should a hot water cylinder sit directly on a concrete slab like this? Or should it be raised off the floor, or have some sort of flooring layer between it and the concrete?

The cylinder is being replaced next week under warranty. The same team who fitted the original are doing the replacement. Should ask them to fit it differently this time around?

 

[bernardgreen]

Yes, Heat loss not the problem.

The base of the cylinder will be affected by cycles of thermal expansion and contraction. Small movements across the rough surface of concrete might be enough to abrade the copper and/or mechanically stress the seam.

A sheet of moisture resistant material with a smooth surface will reduce/eliminate the abrasion.

 

[Peter A]

Thanks Bernard.

The cylinder is a Dimplex model (https://www.dimplex.co.uk/product/quantum-water-cylinder-qwcd) that has the inner cylinder completely surrounded by insulation and an outer plastic case, so no copper directly on the concrete. Reading the user manual, it does say it's intended to be "floor standing" but maybe a layer of vinyl or something might be a good idea.