Hot Water: The Indespensable Luxury

Hot water is central to any luxury bathroom. Regardless of how the bath or shower is configured, abundant supplies of hot water at the desired temperature are what drive consumer satisfaction in the bath.
Successful bath design knows it is selling a total experience, not just a collection of products. In luxury baths, hot water delivery systems may play an unglamorous, behind-the-scenes role, but one that is no less critical to ultimate satisfaction.

Water Heating 101
The most common method of heating water in the U.S. is with conventional tank-style, storage water heaters, which heat and store 30 to 75 gallons of hot water like a thermos, regardless of immediate need; i.e, the unit is cooking water even if no one is using it.
   Tank-type water heaters generally have about 70 percent usable capacity, meaning a typical 50-gallon tank has about 30 to 35 gallons of truly hot water in reserve for usage. If demands run higher than usual over a short period, the reservoir can run dry.
   To put this in perspective, a standard tank-style heater in a comparatively  cold climate delivers enough hot water to power two, 2.5 gallons per minute (gpm) showerheads and three 1 gpm body sprays long enough to take a four-and-a-half minute shower.
  A new technology  (for the US at least), tankless water hearing performs the same hot water delivery function as a conventional water heater. But if properly sized for the application, it does its works in seconds, rather than hours. this savings in time translates into gains in the energy efficiency with no sacrifice in comfort or convenience.
  As the name indicates, there is no hot-water storage with tankless technology. Instead of heating stored water 24/7, tankless units fire up only in response to demand.
   By using more powerful gas burners, a tankless water heater will boost the temperature of the cold water coming into the unit much more quickly than a tank heater can, providing a continuous flow of water at the preset temperature.

Beyond speed, there are differences in the energy consumed by tank-style and tankless heaters.

• The average tank-style heater offers a 60% efficiency rating (6 of every 10 dollars spent on energy produces water water), while conventional tankless units average 83%.
• Condensing tankless water heaters use a second heat exchanger to capture even more heat from the combustion process, raising efficiency to more than 90%.
• Both types of tankless water heaters will maintain this thermal, efficiency rating throughout their 20-year life expectancies, whereas the efficiency of a storage-type unit will drop over its 8 to 10 year lifecycle.

Proper Sizing
 Tankless water heaters are sized by calculating the required temperature rise at a given flow rate, or gpm, for an application. That is, how many degrees the heater must raise the incoming water temperature to deliver the preset temperature at the outlet. Most manufacturers offer sizing guides or online software that help determine the unit best suited to a family's hot-water needs.
  Plumbing system designers and installers consider the following in determining this:

• The flow rate (gpm) required to meet peak hot water demand in a household.
• The coldwater input temperature: the temperature of the water entering  the tankless unit.
• The hotwater output temperature: the desired or preset, temperature of the water exiting the unit.

Using the earlier example of an application requiring a flow rate of 8gpm for two, 2.5 gpm showerheads and three, 1 gpm body sprays, people would need a water heater capable of delivering 8 gpm at a 70-degree F rise.

Smarter Hot Water
Two other key benefits of tankless water heating include:

• Cleaner water: Continuously heating water in a vessel inevitable generates sediment that accumulates at the bottom of the tank, undercutting water heater  performance and shortening its life cycle. In addition, because of all of that sediment, the hot water coming from such a unit isn't terribly clean. technology exists to suppress scale buildup in tankless water heater systems, providing cleaner water for showering and laundry.
• Zero footprint=design flexibility: tankless units are compact and hang on a wall, so they can be located virtually anywhere inside the home. this means these heaters can also be installed closer to the point of use-such as a new master bathroom. this proximity should result in reduced waiting time for hot water.

  Many bath designers do not get involved in selecting and sizing water heating systems. But taking a more comprehensive approach will enhance a value to the client while ensuring the performance of the space.