WATER HEATING

Whether showering to prepare for a busy day or looking forward to a nice soak in the tub after a stressful day, an adequate supply of hot water is essential for the bathroom, as well as other rooms in the home. To ensure that hot water meets the demand and your client’s satisfaction, plan the hot water needs carefully so that plenty of water will be available during peak use times.

Water Heater Location

How quickly hot water arrives to the bathroom fixtures can vary depending on the location of the water heater in relation to the bathroom. A somewhat common home design scenario is where the bathroom ends up on the opposite end of the house from, or two stories above, the home’s water heater. Not only does this make for a long time lapse before hot water reaches the bathroom fixtures, but a large amount of water is wasted while waiting for the hot water to arrive.

If this appears to be an issue, a second water heater located near the bathrooms, would be a good idea. A second water heater may also be recommended if your client wants to install a whirlpool – type tub or multihead showers that require a large amount of hot water.

Selection Considerations

If after evaluating the hot water situation of your client you decide you either need to replace and/ or upgrade the hot water source and delivery system, there are a number of factors to consider. These include fuel type, heater type, size, energy efficiency, and cost.

Water Heater Types

Water heaters can be of three basic types—tank, on-demand, and hybrid. The type best fits your client’s needs depends on their hot water needs, storage space, and home size.

• tank. Tank type units are what we commonly see in U. S. homes. This type of water heater keeps water hot on a 24-hour basis, adding more heat when the thermostat is below the set water temperature. Because these standard tank units keep water hot all the time they are more en­ergy intensive than other types. Some larger households may have one tank located in the ga­rage or basement and a second tank on the second floor or across the house. These tanks vary in size and fuel type and require a space large enough to store the tank.

• On-demand. On-demand water heaters, also called instantaneous water heaters, are becoming more popular and can also vary in size and fuel type. An on-demand water heater heats the water to a preset temperature as it is used and therefore does not require a storage tank. Smaller units are becoming popular in the kitchen as an instant source of near-boiling water for instant soups, coffee, tea, and other drinks. These units can be located in a cabinet under the sink or wherever the fixture is located. Whole-house units are large units that supply enough water for the entire home and are also wall mounted, typically in the garage or basement. Efficiency ratings of these units can vary. All whole-house units are limited in their capacity, es­pecially the electric type, so be sure to carefully calculate the client’s needs if you recommend this type of water heater.

Fuel Type

Water heaters can be fueled by a number of different sources and the type you choose depends on the client’s preferences and where they live. Each has its advantages and disadvantages.

• Electric. Electric units are typically less expensive to buy but will generally cost more to operate, unless it is a heat pump water heater (HPWH). If a standard tank style electric water heater is your only option, it is very important that it be an energy-efficient model. Selecting an efficient model is discussed later in this section. Standard electric units contain two heating elements, one about a third of the way down inside the tank and the other closer to the bottom. If one of the elements burns out, the water heater will not supply hot water at the typical rate. The heat pump water heater is a tank style electric unit that works just like the heat pump home heating systems. It removes heat from the outside air and transfers it to the water to be heated.

These are more efficient than a standard electric element tank system but are expensive to buy. They also work best in climates where temperatures are between 40 and 90 degrees Fahrenheit (4.4 and 32.2 degrees Celsius) year-round.

Instantaneous or demand water heaters can also be electric. Smaller units are used for one specific usage. Whole-house electric units cost about the same as a standard electric tank unit but save on operating costs and last longer. Don’t forget that they require an extra circuit for operation.

• Gas. Natural gas and propane (also called LP) water heaters are typically more expensive to buy but they cost less to operate. One drawback of the natural gas heater is that you need to have a natural gas pipeline nearby. Propane requires a tank placed in the backyard and is used when gas is desired but natural gas is not available. Gas tank water heaters have a gas burner at the bottom of the tank. The gas burner that heats the tank is ignited by a standing pilot light or a spark ignition. As the gas burns, it heats the water in the tank and releases carbon monoxide (CO) formed during the combustion process. These gas heaters vent out the CO through the center of the water heater to the outside, typically through the roof. This vent can be either a natural draft vent or a forced air vent which boosts the CO release with a fan.

A more efficient style of tank gas water heater is the condensing heater. Condensing units dif­fer in that they have a sealed combustion chamber inside the tank. As the combustion gases are exhausted they pass through a coiled steel tube within the water tank which is a secondary heat exchanger. The hot gases move through the heat exchanger, transferring additional heat to the water. When all of the heat is released the combustion gases cool to a point that water vapor is formed. The resulting vapor is now cool enough to be safely vented through inexpen­sive plastic plumbing pipe, far less expensive than the stainless steel flues needed for a standard gas water heater. These water heaters have an efficiency of 90 to 96 percent compared to the 60 percent for the average tank water heater.

Most of the larger on-demand heating units are gas fueled. They require a vent to the outdoors and sometimes a large gas line. They are also more expensive to buy than a standard tank gas water heater, but can save money over time.

• Solar. Solar water heaters may be a good option if you live in a sunny climate. A typical solar water heating unit has a panel mounted to the roof. The ground is another mounting location but they are more prone to damage and shading in this location. The solar panels contain tubes where either the water or a heat transfer liquid passes. As the sun strikes the panel it heats the water or liquid in the tubes. The water would then go to a storage tank for use. The heat transfer liquid would pass through a heat exchanger where the heat would then be used to heat water in a tank.