Insulating a Cold Water Tank

The Cold Water Tank

Traditionally, cold water tanks (or cisterns) were made of galvanized steel. When these corrode beyond repair they are replaced with plastic versions. These are lightweight and come in standard 227 litre (50 gallon) capacities – although larger ones are available. Some plastic cisterns are ‘collapsible’ and they can be wound with rope making it easier to get them through small access hatches into the roof space. Before you buy a new tank, check the dimensions of the access and the amount of space in the roof so your new cistern can be installed easily. Because they are fairly flexible, plastic cisterns must be supported on a flat base.

Cold Water Tank Insulation

The simplest method of insulation is to buy a ready-made ‘jacket’ that fits around the cistern. Since tanks are standard capacity, so are the jackets. Remember that the ‘lid’ should also be insulated. The insulation jacket simply slips around the cistern and is held securely with plastic tape or one or two ‘belts’ of rope. Don’t tie a fixed knot in the belt or you’ll have to cut it off; instead tie a granny knot with draw loops, like the ones used to tie shoelaces. That way you’ll be able to untie the belts easily to inspect the cistern and the float valve and carry out any repairs. Don’t forget that the cold water pipes leading to and from the cistern also need insulating. If the pipes run between the joists you can lay blanket insulation over them. If not, then lay each of the pipe runs individually.

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