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  • Writer's pictureCA Mechanical


A tankless or on demand water heater is just that; a water heater, minus the tank. On demand water heaters only heat water when you turn on a faucet as it flows through the system. There is no storage tank that has to be continually kept at 120F degrees like a traditional tank style water heater.

The biggest difference between a tankless water heater and a traditional water heater is the on-demand nature of it. On demand water heaters are able to be installed in a greater Seattle area home at multiple points of use, in order to provide the entire home with endless hot water.


One of the big advantages of a tankless water heater is that when you turn on the hot water faucet, you don’t need to wait for the hot water to warm up – it’s there for you, immediately.

Electricity or a gas burner constantly warms the water; thus the reason it is called “on-demand.” You can expect an average cost savings of 20-35% off your monthly energy bill, dependent upon the quantity of water your household requires. The savings is due to fact that tankless water heaters do not have to continually heat water as is necessary for a tank style water heater. Also, a tankless water heater is 97% energy efficient, compared to 60% energy efficient for a typical tank style water heater.

The instantaneous nature of tankless water heaters also will save money on your water bill. There is no longer the 2-3 minute wait as the water warms up to wash your hands or take a shower, so your family members can immediately use the water and not waste a lot of gallons with each use.


One of the drawbacks of an on demand water heater is that the flow rates may be limited, especially if you have a large home and you are washing clothes and someone is taking a shower at the same time.

The remedy is fairly simple – install more that one tankless water heater in your home to meet the demand of simultaneous uses. It’s very common to use a separate water heater for a dishwasher, washing machine, or a remote bathtub that is on another level of your home on the opposite side of the kitchen.


According to ENERGY STAR® a family of four can save upwards of $100 per year or more when using a tankless water heater, especially if you install one at each hot water outlet.

For a home that uses less than 45 gallons a day of hot water, your energy usage can be 24%-34% more efficient versus using a conventional tank water heater. However, if you use over 86 gallons of hot water a day, your savings drop to between 8% and 14%, still significant.

The cost of a tankless water heater is more expensive that a conventional water heater, but in the long-term your investment is probably worth it; most tankless water heaters are built to last upwards of two decades, compared to a traditional water heater that lasts half that time.

Replacement parts for a tankless heater are readily available and can extend the life even more. So, in many cases it is worth the investment.

Installation of the tankless water heater should be done by a professional plumber, due to many factors, including building codes and permits in some cases. Most importantly, safety issues are a concern if you are dealing with a gas water heater.

Think carefully about this decision to switch or upgrade – call us to come out and take a look at your home or place of business. We’ll be happy to give you an estimate!

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