Canada Mortgage and Housing Corporation

Canada Mortgage and Housing Corporation

October 05, 2012 11:01 ET

Stop Heat From Going Down the Drain

OTTAWA, ONTARIO--(Marketwire - Oct. 5, 2012) - In Canada almost 20% of our household energy is used to heat water and much of this simply drains away as wastewater. However, you can save on water heating costs by capturing this heat with a drainwater heat recovery system.

Instantaneous drainwater heat recovery systems can be installed on the drainline pipe coming from showers. The system consists of copper piping coiled around a drainpipe installed in the drain pipe serving a shower (or showers) above. Heat is transferred from the warm wastewater flowing down the drainline to the cold potable water flowing up through the copper coil. The heated potable water can be used immediately for showering, thereby using less hot water from the tank, or delivered to the hot water tank, where less energy is needed to heat it. The trick is to ensure that cold potable water is running up the system at the same time as drainwater is coming down or the heat cannot be captured.

Testing undertaken at the Canadian Centre for Housing Technology in Ottawa found that showers equipped with drainwater heat recovery units provided hot water up to 2.5 times longer than systems without heat recovery depending on whether the system was used to heat water directed to the shower water only or to the shower and hot water tank.

Drainwater heat recovery systems can vary in length and the way the copper tubing is wrapped around the drainpipe. This can affect water pressure to the shower; therefore, consumers with low water pressure in their homes should look for systems that minimize pressure loss.

Make sure to choose and install the appropriate sized system - check drainpipe size, drainwater heat recovery unit height, potable water pipe size, and any requirements for low pressure loss devices.

Drainwater heat recovery systems can cost between $400 to $1,000 plus installation. Annual savings for drainwater heat recovery can range from $49 to $168 depending on the brand of heat recovery unit chosen and the type and cost of fuel energy (electricity, oil, or gas) you use for hot water heating. Lifestyle choices such as taking baths instead of showers and the number of showers per day will also affect potential savings. You can search online for drainwater energy savings calculators to help you determine your potential annual savings by plugging in information on your drainwater system, fuel costs, and shower usage.

A properly installed drainwater heat recovery system can help extend hot water availability for showers and reduce your hot water heating bill. If you are considering installing this system be sure to consult an experienced plumber to make sure it is done correctly.

To help you learn more about drainwater heat recovery, check out Canada Mortgage and Housing Corporation's Research Highlight on Drainwater Heat Recovery Performance Testing at CCHT. Download your free copy at or call 1-800-668-2642.

For over 65 years, Canada Mortgage and Housing Corporation (CMHC) has been Canada's national housing agency, and a source of objective, reliable housing information.

Contact Information