Residential use wall mounted water boilers are tankless and are designed to heat water only when a hot-water faucet is opened. Also called instantaneous water heaters, they are available in electric, gas, and propane-heated units.
Most people think that instantaneous means that, when you turn on the tap, hot water comes out instantly. This is not always the case; the heater does not store hot water but produces it on demand. If the heater is not close by, you still have to wait for the water to get to you. You could, however, take a shower for twenty-four hours since there is no tank to empty. Because it makes only so much water per minute, you cannot use one heater for two applications at once. One great use for tankless water heaters is vacation homes.
A wall-mounted heater may be a good choice for your home, but there are lots of options to consider before you make this choice.
Wall-mounted tankless water heaters have lots of advantages. They are compact and electric units can fit almost anywhere—even in a closet. They are quiet. Your water-heating energy efficiency is increased, and therefore utility bills are smaller. You gain this efficiency because your system is not heating the water over and over, but just when it is demanded. There is no tank of water sitting around, which you know is important if you have ever had one rupture. Gas-fired units are mostly rated at 80 to 85 percent efficiency, while electric is usually almost 100 percent!
Before you think all of this sounds so great that you are ready to call the plumber or contractor right now, consider the down-side of these units. First, a gas-fired wall-mounted heater must be vented to the outside through a wall. Installing this vent is very expensive. Because electrical, gas, and water connections will have to be rerouted to the new heater, you must hire an electrician and plumber to do the work. Gas tankless heaters require an annual inspection.
Because an electrical system does not have to be vented to the outside, it can be installed virtually anywhere the water lines can be connected. It heats the water with an electrical element in the waterline. Have a licensed electrician install the required two or more 220-volt 40 to 60 amp circuits, and to connect the lines to breakers. Some areas don’t have available gas lines, and electricity becomes the only option; and in some parts of the world, electricity is cheaper than gas. Unit costs and maintenance costs are definitely much more affordable with electric units. About the only maintenance needed is to clean the input screen occasionally, and to run white vinegar through the system once a year. Vinegar removes all the calcium deposits that build upon the heating element and inside the pipes. (For instructions on this watch the video on ehow.) And if there is a problem, the heating mechanism is much simpler than that of gas models, meaning it is much easier to repair.
How Much and How Hot?
The amount of rising in temperature (how hot you want comparing to the temperature of incoming water) determines the flow rate, so you must consider this factor before you choose any type of heater. With the majority of tankless water heaters, the maximum is 2.5 gallons per minute. This is really sufficient for any household, but many people are used to more. It is hot enough and a high enough flow rate for dishwashers.
So Which One Should I Buy?
The things to look for in a wall-mounted water heater include: capacity; how it compares to energy efficiency requirements; what protection does it have against dry heating; does it have fully automatic controls; what is the external temperature of the unit; how will it be mounted (most residential units are shipped with factory-installed mounts); and what materials were used to make the unit and the liner?
For more detailed advice go to the series of useful articles about tankless water heaters on ehow.com.
Choosing a wall-mounted water boiler can be easy if you do your homework and understand what is involved in installing and using the unit. Certainly having instant hot water is really appealing, and the resulting energy savings might make the decision clear.