Tankless Water Heaters
We have a favorite Italian deli in our neck of the woods that we love to visit – probably more often then we should. Due to its popularity, everyone must “take a number,” which determines the order of service.
Waiting in line from time to time at a popular local deli is within the scope of “reasonable.” However, drawing numbers at home to determine who gets to shower first is pushing the envelope. Ironically, it’s a daily routine in many American homes due to a finite supply of hot water. The problem gets worse as a home’s head count rises and there are more showers to take, clothes to launder and dishes to wash.
In most American homes, hot water is generated in a tank type gas-fired water heater. It is, for the lack of a better description, a large thermos with a burner at the base. Cold water enters the top of the tank and is delivered near the bottom via a small plastic pipe called a dip tube. A thermostat measures the temperature of the water and activates the burner to heat the water to the desired temperature. When the demand exceeds the supply, the familiar “cold shower” ensues, which is abated once the water heater has had time to heat a fresh tank of water – usually several minutes. The problem is made worse in winter when the ground water is colder and the water heater must work harder to raise the water temperature.
There is yet another factor that challenges the effectiveness and efficiency of a tank style water heater – sediment. Over time, sediment (hard water deposits, calcium carbonate, etc.) accumulates at the base of the tank, which significantly reduces the effectiveness of the burners and curbs energy efficiency. Innovations in tank type water heaters such as curved dip tubes that are designed to prevent sediment from collecting have helped to curb the sediment problem. However, for maximum efficiency, all tank type water heaters should be periodically flushed.
Though tank type water heaters have been the water heating standard in America for decades, there is a new kid on the block that is making Americans stand up and take note – the tankless water heaters. Although the tankless water heater is relatively new to American households, it has been the standard in other parts of the world, most notably Europe and Japan where energy resources are more precious than even those of the U.S.
As its name implies, a tankless water heater has no holding tank. Instead, it heats water instantaneously, as it is needed, in a fin tube heat exchanger. What’s more, since no storage tank exists, there is no standby energy loss associated with the storage of hot water; there is no standing pilot and no sediment buildup to deal with.
When you open the tap the tankless water heater senses the flow and the electronic ignition starts the water heating process. The water flows through the heat exchanger and is heated to the temperature you choose. Then, the hot water is delivered to the taps in your home that are open. Most tankless water heaters are microprocessor controlled and use feedback from a water flow sensor to adjust the burner, which delivers a consistent water temperature. This is an especially important feature if you have small children or elderly people in your home. When the tap is closed the tankless water heater shuts off.
A tankless water heater provides continuous hot water and never runs out. However, the volume of hot water — measured in gallons per minute of flow (gpm) or “flow rate” — provided by this style of heater has to do with several factors.
First is the size of burner. The bigger the burner, the greater the flow rate. For example, a tankless water heater with a Btu input of 175,000 can produce up to 6.3 gallons per minute, which is enough hot water to take up to three simultaneous showers in summer (where the ground water supply is at least 68 degrees Fahrenheit). Conversely, a unit with a Btu input of 380,000 can have a flow rate of up to 13.2 gallons per minute; enough to take up to six simultaneous showers where the ground water supply is at least 68 degrees Fahrenheit.
Chances are good that you won’t be taking six simultaneous showers, but, if your home is anything like most American homes, simultaneous showering, clothes laundering and dishwashing is the rule. The flow rate for most of these units is designed to allow for all of these activities to occur simultaneously.
As you may have gleaned from our prior comments regarding ground water temperature, it has a great deal to do with the flow rate of a tankless water heater. Using our example of a unit with a Btu input of 175,000 that can produce up to 6.3 gallons per minute in summer, the same unit can produce enough hot water to take up to two simultaneous showers in winter (where the ground water supply is approximately 41 degrees Fahrenheit). The unit with a Btu input of 380,000 drops to five simultaneous showers where the ground water supply is at least 41 degrees. In short, flow rate is diminished as the temperature rise (the number of degrees needed to raise the temperature to the desired level) increase. Some units can be “piggy-backed” to provide a flow rate that is especially suited to meet the specific needs of your home and family.
If you haven’t seen a tankless water heater you’re in for a surprise. It looks nothing like a conventional tank type water heater. Though size varies based on rating, the average size is about 24 inches high, 18 inches wide and about nine inches deep – taking up a little more than two cubic feet. They are wall mounted and unlike a conventional tank type water heater, they can be mounted both indoors and outdoors. A state-of-the-art electronic controller allows for easy temperature adjustment.
When it comes to cost, plan to spend several what you would otherwise shell out for a tank type unit. Tankless water heater costs range from $500 to about $2000 for the average residential unit. The good news is that most units come with a ten year warranty and industry estimates demonstrate that tankless units can save up to 46 percent on water heating costs, which, based on the increasing cost of energy, can be a pretty penny. Thus, the higher purchase price can usually be recouped after just a few years of use.
In days gone by we have been cautious – even anti tankless water heater. With time and improved technology we give tankless water heaters two thumbs up!
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