Domestic Water Heating

Scale and Water Heaters To keep water heaters running at peak efficiency, it’s important to remove scale from inside the tank. Regular scale removal saves money and prolongs the life of the entire water heating system. Scale is a hard, whitish coating that can build up on any surface that comes into regular contact with hard water. Hard water contains more minerals than soft water, and mineral levels vary from city to city. Generally speaking, groundwater contains more minerals because minerals from the soil are in the water. River or lake water usually contains fewer minerals and, therefore, is softer.

Courtesy of Delta De-Liming

Does it really matter?

Scale buildup can reduce the useful life of a water heater by as much as 50% and greatly increase operating expenses. Scale that accumulates inside a water heater covers the inside walls and heat exchanger surfaces, increasing operating time as these surfaces lose direct contact with the water. As little as 1/16" of calcium scale on the heating transfer surfaces can reduce heating efficiency drastically. That means the heater has to run more often and longer, shortening its life, increasing repair costs and driving up operating costs.

Often the heater will make loud knocking or rumbling noises because of water boiling between the scale and the tank wall. The hot water  may smell musty or look murky, and will discolour surfaces that it contacts. Occasionally. there will be white flakes in the hot water.

Reduced energy efficiency

Maintaining higher operating temperatures and heating water through a layer of scale increases the water heater’s energy consumption. Scale build-up can reduce a gas water heater’s efficiency by up to 30% and also reduce its life. All else remaining equal, energy consumption increases as the scale thickens.

Read a descaling case study.