WetbackA wetback is a heat exchanger incorporated in the firebox of a woodstove connected to a raised hot water cylinder by two pipes, one higher than the other. As the water heats and becomes less dense it travels up the top pipe to the hot water cylinder and is replaced by the denser(cold) water from the bottom of the hot water cylinder.

The benefit of a wetback is that the fire is probably already in use either for heating the house, cooking, or both and only requires you to light a fire to start the process. Depending on the size of your hot water cylinder and the efficiency of your stove it can take between one and three hours to heat the a normal sized hot water cylinder and during the summer period this can be a sweltering event. Pairing a wetback with a solar water heater can solve this problem and provides a robust complimentary hot water system – in the summer solar provides your heating and during winter the wetback heats your water at the same time as heating your home.

Some drawbacks of a wetback are that during the warmer months you can find yourself lighting a fire and opening all the doors and windows to keep the house a reasonable temperature. A wetback (and all other hot water systems) require a tempering valve (installed by a registered plumber) to ensure temperature control so as not to create the risk of someone being scalded.

Wetback cost example

Wetback installations require consent. Ask your plumber or contact the Auckland Council.

Hot water cylinder

Hot water cylinder with wetback connections.


Copper Piping

Piping and connections.



Each installation will be different.



Including GST.



Great Barrier Plumbing & Drainage

Certified Plumber, Drainlayer, and Licensed Gasfitter.

Ph:09 4290 298
Mob: 027 429 0298

Last updated on the 06-04-2020