Comparing Tankless to Traditional Water Heaters
Should you get a tankless hot water heater? What are the pros and cons? We've all heard about the economic reasons why these are a good idea, but those aren't the only factors to consider.
Your water heater is a major energy consumer - probably the biggest single draw on power if you have an electric heater - which costs about 14% of the average home's energy budget. A more efficient and cost-effective alternative has been around for a while, but in these days of super-high energy costs is drawing more and more interest. This alternative is a tankless hot water heater that can save an estimated 10-20% of your water heating bill. The interesting thing is that most of the energy is lost while just keeping the water hot in the tank, which is known as standby losses. These losses can add up significantly.
Tankless water heaters provide hot water when needed without storage, thereby reducing or eliminating standby losses. You can use tankless water heaters as part of a whole-house heating system, as a supplement to solar hot water systems, or to just provide the house with hot water. The system delivers hot water when it is needed - no more paying to have hot water sitting in a tank!
Some additional environmental benefits include lower transportation energy consumption due to the units being smaller and using fewer materials.
Tankless water heaters can be powered by electricity, gas, or propane. The heating device is activated by the flow of water and provides a constant supply of hot water. How much water flows through at the required temperature is determined by the capacity of the heater. Gas tankless water heaters typically have larger capacities than electric tankless water heaters.
These units range from large whole-house water heaters that are usually located in a central point in the house, to smaller point-of-use units like those instant hot water units located under the kitchen sink.
Tankless water heaters are rated by the maximum flow rate at which a desired temperature rise is met, for example, 3 gallons per minute. Residential gas models are available that can heat more than five gallons per minute by 60°F, which will let you run two showers simultaneously. Whole house electric units typically have a capacity closer to three gallons per minute. Because of this and some of the other factors that must be considered, gas-powered units are better choices for whole-house units.
Energy Efficiency - Greater
Tankless water heaters are more energy efficient because they have almost no standby losses. With gas powered unit, sealed combustion gas units burn fuel more efficiently than the standard natural draft gas water heaters. Research has shown that energy use can be cut by 10-20% percent compared to a conventional water heater. Some models are eligible for eligible for a $300 Energy Tax Credit by the Federal Government.
Ease of Installation - Not-so-easy
The best time to put in a tankless hot water system is during new construction. To minimize energy-stealing long hot water runs, heaters should be centrally located in the house. It is also more economical to do the electric wiring and/or venting while the house is under construction.
Changing over from conventional water heating systems to tankless one can be, like many retro-fits, difficult and expensive. Because the tankless electric heaters need approximately four times the electricity to operate, additional wiring and possibly a higher capacity main electric panel may have to be installed. Many gas tankless manufacturers recommend a direct vent to supply fresh air from outside for combustion and vent the flue gas using a blower through a side wall.
Initial Cost Greater than comparable products
The installation costs of tankless water heaters are from 2 - 4 times higher than tank-type water heaters. For gas tankless hot water heaters, the same gas supply line and/or venting may need to be sized larger than for a typical gas tank. Electric tankless water heaters draw more power and will require multiple circuits and/or heavier cable, which will increase installation costs. Water connections for both are similar or identical to those used on tank-type water heaters. In some cases, the temperature and pressure (T&P) valve necessary for tank systems may not be required for a tankless heater. (Check with your local code official)
Gas and electric whole-house tankless water heaters are more expensive than typical tank systems except when compared to high efficiency tank systems. In these cases, the high efficiency tanks may be close in cost to the tankless systems.
Tankless water heaters range in price from $200 for a small under-sink unit to $1200 or more for a gas-fired unit that delivers 5 gallons per minute. Typically, the more hot water the unit produces, the more it will cost to buy.
These heaters make more economic sense if you plan to stay in the home long enough to recoup your up-front costs via several years of energy savings.
Operational Cost - Less than comparable products
Electric tankless water heaters generally cost 10-20% less to operate than comparable tank-type water heaters. Gas savings may be about 20 -40%. Equipment life may be longer than tank-type heaters because they are less subject to corrosion. Expected life of tankless water heaters is 20 years, compared with between 10 and 15 years for tank-type water heaters.
U.S.Code Acceptance
Tankless water heaters can be used to replace tank systems almost anywhere. Code restrictions concerning use of a T&P valve may apply in some areas. Venting, airflow and spacing requirements that might limit the location of the tankless water heater will be dependent on the manufacturer's installation requirements and should be followed precisely.
Installation
Installing tankless water heaters not too different than installing a tank-type heater. Water, gas, and electrical connections are almost the same, although as noted earlier circuits and wiring may need to be beefed up to handle the high instantaneous power load. Physically, the units are usually wall mounted.
Most point of use units are installed under sinks, in closets, or in other areas where they can be easily accessed. These units are usually electricity-powered and can often operate off of a standard outlet. Usually these units must have a hot water line that is separate from the whole-house water system.
Warranty
The warranties of tankless water heaters are generally longer than those of comparable tank-type units. Typical limited warranties are 2-5 years for the unit, and 7-10 years for the heat exchanger. Expected life of tankless water heaters is 20 years, compared with between 10 and 15 years for tank-type water heaters.
Benefits/Costs
Tankless water heaters are compact in size and are more energy efficient. They can provide warm water to even the furthest points of the house, and less water is wasted while waiting for warm water to reach a remote faucet. A tankless water heater can provide unlimited hot water as long as it is operating within its capacity.
Equipment life may be longer than tank-type heaters because less subject to corrosion. Expected life of tankless water heaters is 20 years, compared to between 10 and 15 years for tank-type water heaters.
Tankless water heaters range in price from $200 for a small under-sink unit up to $1200 or more for a gas-fired unit that delivers 5 gallons per minute. Typically, the more hot water the unit produces, the higher it will cost.
In most cases, electric tankless water heaters will cost more to operate than gas tankless water heaters.
While the usage cost savings may be a strong selling point, you will need to enjoy the heater for long enough to get those savings. This is not a system that you will want to install in a home that you plan to sell in a couple of years, unless the installation is done during construction. The real benefit of the tankless water heating system is more in the luxury of having hot water whenever you want it, without having to wait for the tank to heat up. Families with teenagers will appreciate this!
When coupled with a home heating system, the heat quality and consistency can't be beat. No drafts, no dirty duct system, no noisy heaters or machinery. Air humidity is also better than the typical furnace or electric baseboard system.
There are many reasons to choose a tankless water heating system, and comfort is at the top of the list!