Hot water cylinder insulation

Insulation jackets are commonly added to hot water cylinders in England, New Zealand and other countries . We are slowly becoming more aware of their potential here in Australia.

While internal insulation of hot water cylinders is improving, significant heat loss still occurs with all storage cylinders, including solar boosted cylinders, regardless of age. See this article for summary of typical energy loss of hot water cylinders.

Unless your water heater's storage tank already has a high R-value of insulation (R>4.0), adding insulation to it can reduce standby heat losses by 25%–45%. This will save you around 4%–9% in water heating costs.

Hot water cylinders do not generally advertise their R value rating in Australia. If you don't know your water heater tank's R-value, touch it. A tank that's warm to the touch needs additional insulation.

A proprietory cylinder wrap called GreenStuf EcoWrap hot water cylinder wrap is made from polyester insulation adhered to a foil backing.  The kit provides enough blanket to insulate most hot water cylinders as well as tape and instructions.

A cheaper alternative is to buy a roll of foil backed insulation (Bradford Anticon). The rolls are 15 m long, enough to do at least three large cylinders. Share a roll with family!

CLICK HERE for instructions on installing additional insulation to electric storage hot and solar hot water systems from US Department of Energy.

Alternatively, a shelter or cover can be built around the cylinder if it is exposed to the outside elements, sheltering it from the weather. This can be further improved by lining the walls with a reflective material such as sisalation to reflect radiant heat emitted from the tank, reducing the heat loss. Otherwise the shelter can be packed with spare insulation batts.

When wrapping a cylinder remember to keep the thermostat panel at the bottom of the tank and presssure relief valve accessible for maintenance.


Autex Ecowrap may be ordered directly from The Enviroshop on-line shop. postage is on top of the price ($99).

Clennetts Mitre 10 have advertised they sell the Ecowarp, but they may have to order it in.

Bradford Anticon can be bought from

Cowleys Interior Supplies Pty Ltd
Ph 6234 3481
Supply only or supply and install Bradfords products

Becks Hardware (Span Truss Systems)
30 Patriarch Dr, Kingston
Ph 6229 1148
Supplies E-therm 2 in 1 foil insulation. Also sells Bradfords insulation and FoilBoard.