The Advantages of Instant Hot Water Dispensers

Lots of people love the idea of having an instant hot water dispenser in their kitchen. Using instant hot water allows you to make hot cereal in the blink of an eye, or a cup of tea almost as fast as you can make a cup of instant coffee. And that ready supply of hot water makes clean up a breeze.

How Does an Instant Hot Water Heater Work?

Instant hot water heaters are basically small electric hot water tanks (none of them are gas fired). A small tank holds the hot water ready for use, just waiting for when you turn on the special instant hot water tap at the sink. Water is supplied to the tank through a small water line that runs off the sink's main cold water feed line. It comes into the base of the tank, where it's heated by an electric element. This heating causes the water to expand, and it moves up into a holding tank in the top of the tank where it is kept hot. When you turn on the dedicated tap, hot water flows out the top and fresh cold water flows in at the bottom.

Instant hot water dispensers range in capacity from 1/3 to 1/2 gallon, and the heating elements vary from 500 to 1500 Watts. It's estimated that a 750-watt 1/2-gallon tank can deliver up to 60 cups of hot water in an hour. Since the instant tanks produce water that is substantially hotter than regular hot water tank (about 190 degrees versus 120 degrees), the water is delivered at a much slower rate than a regular hot water tank (about one ounce per second).

Most instant hot water tanks have a thermostat that allows you to adjust the temperature if the water is too cool, or if it's too hot and boils away. You can get instant hot water heaters that are part of "total" water systems as well. Some are produced with integrated water filters or even water chillers to provide pre-chilled drinking water.

Can I Install an Instant Hot Water Tank?

This saddle valve is used to install an instant hot water dispenser. It attaches to a pipe using the bracket and screws, and the needle point (shown half-extended) is screwed into the pipe and makes a hole. When the needle is screwed back out, water will come out the hole and flow through the feed tube that attaches to the compression fitting.

Instant hot water tanks are often included as part of a kitchen remodel and installed with new sinks that have a hole already cut to accept the extra hot water spout. However, if you have enough existing space under your sink, retrofit tanks are available at home stores. These can be easily installed, particularly if your existing sink has a separate spray nozzle - just remove the sprayer and use the hole to accommodate the new spout. Failing that, a plumbing contractor could drill a hole in a stainless steel or even a porcelain sink (although there would be a risk of cracking the porcelain).

Installation itself is fairly straightforward. Vertically mount the storage tank under the sink, install the new faucet and run the feed line from it to the top of the tank. Then, using a saddle valve, tap into the sink's main cold water supply and run a 1/4" feed line to the bottom of the new tank. The heating system will have a three-pronged plug that goes a grounded, 15-amp receptacle under the sink.

Do I Have to Pay a Lot for the Convenience?

An instant hot water dispenser will cost from about $150 to $350, with the higher priced units including extra features like the water filters and/or water chillers. If you get a system with water filtering capability, you will also need to consider the cost of replacement filters. You would be well advised to find out whether replacement filters are widely available and how much they cost before you buy. The dispensers themselves use about 1/2 kWh of electricity per day, so the cost of operating one would depend on the cost of power in your area, but a rough estimate would be less than 10 cents a day.

Some people likely think that an instant hot water is impractical. However, consumer feedback is that once you've lived with one, you don't want to go back to not having one - kind of like air conditioning in a car. Some of us can remember when all cars didn't have air conditioning, but we sure wouldn't want to try going through a summer without it now.

Read our article on Tankless Water Heaters for another hot water option.

If you're looking to purchase a water dispenser, check out our Water Dispensers Buyer's Guide.