Insulate hot water system, pipes, and valve

pipes.pngWrap them up to make sure the energy and money you used heating your water doesn't go to waste.

Ever touched the outlet pipe on your hot water system? Careful, it's hot! That heat is constantly wasted; lost to its surrounds. The same goes for the pressure and temperature relief (PTR) valve, the drain pipe, and the cylinder.

A poorly insulated system located outdoors can lose up to 3kWh/day, which costs $185/year! Adding insulation is a cheap and easy DIY job that can slash these loses.


Pipe insulation (or 'lagging') comes in various materials, and is available from hardware stores. Measure the length of the pipes you’re insulating and their diameter before buying your insulation. Once you’ve installed it, use electrical tape or cable ties to secure it in place.

Most important is the outlet pipe from the hot water cylinder and the drain pipe (which comes off the PTR valve) as these lose the most heat. You should also consider insulating hot water pipes throughout your property, especially if they are outside or otherwise exposed to cold temperatures. This will make the hot water that reaches your taps hotter, meaning you use less to achieve the same temperature, saving energy in the process. Sometimes it will also keep the water in the pipes warm enough between uses, saving both energy and water.

Pressure and temperature relief valve.

The pressure and temperature relief (PTR) valve can be found near the top of your hot water system. It is an essential safety feature that relieves excess pressure from your hot water system so it doesn’t crack, or worse. But they lose a lot of heat, and this is really easy to fix. 

A natty Aussie invention, the Valve Cosy, is ridiculously easy to install. It takes just seconds to clip this insulated plastic enclosure around your PTR valve. Alternatively, you can use pipe lagging or other insulation, but they are an awkward shape and you need to be very careful not to obstruct the PTR valve from being able to be tested, or from performing it's important safety function. 


While hot water cylinders have some insulation, it is often inadequate, especially in older models. If the outside of your cylinder is warm to touch then it would benefit from additional insulation - especially if it is located outdoors or in a cold part of the house.

You can wrap and tape insulation to your cylinder (it's easiest to make it neat and water proof with foil-faced insulation), or build an insulated cabinet around it. Either way, be sure to maintain easy access to the electrical panel and the PTR valve, and be very careful not to obstruct testing or functioning of the PTR valve.

We definitely recommend doing the pipes and PTR valve. With the cylinder you may be better off getting a new efficient hot water system (these have better built-in insulation) rather than spending time and money on insulating your old cylinder that may not have a lot of life left in it anyway. But if you're keen, then go for it!