Post by ogeezer on Apr 19, 2007 11:29:45 GMT -6
Ridding your home of the water heater tank will likely shave 10-20 percent off your water heating bill by eliminating standby losses of energy consumed from having warmed water sitting in a tank. And, since water heating accounts for about 14% of the average U.S. household energy budget, this can be a significant loss.
Tankless water heaters provide hot water at a preset temperature when needed without storage, thereby reducing or eliminating standby losses. They can also be used for supplementary heat, such as a booster to a solar hot water system, or to meet all hot water needs.
Tankless water heaters can employ electric, gas, or propane heating device that is activated by the flow of water. Once activated, the heater provides a constant supply of hot water. The maximum flow rate at a desired temperature will be determined by the capacity of the heater.
Gas tankless water heaters typically have larger capacities than electric tankless water heaters.
Large units for whole house water heating use are located centrally in the house.
Tankless water heaters are rated by the maximum flow rate at which a desired temperature rise is met. Special features may allow the user to set the delivery temperature. Efficiency is higher than an equivalent tank type water heater because standby losses are virtually eliminated. Residential gas models are available that can heat more than five gallons per minute by 60°F, generally more than enough for two showers to be run simultaneously. Whole house electric units typically have a capacity closer to three gallons per minute.
DESIGN & SETUP - New construction is the best time to introduce tank- less water heaters to maximize the benefits & minimize initial cost. Heaters can be centrally located in the house to minimize hot water runs.
Many gas tankless manufacturers recommend a direct vent – this will bring in fresh air from outside for combustion and vent the flue gas using a blower through a side wall.
INITIAL COSTS - Installation costs of tankless water heaters are from 2-4 times higher than tank-type water heaters. Accordingly:
Whole-house tankless water heaters are more expensive than current tank systems except when comparing 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 up to $1200 for a gas-fired unit that delivers 5 gallons per minute. Typically, the more hot water the unit produces, the more it will cost.
OPERATING COSTS - Electric tankless water heaters generally cost 10-20% ($40-80/yr) less to operate than comparable tank-type water heaters. Gas savings may be about 20-40% ($50-$100/yr). Equipment life of tankless water heaters is 20 years, compared with between 10 and 15 years for tank-type water heaters.
BUILDING 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 mfg's installation requirements and should be followed precisely.
INSTALLATION of tankless water heaters is very similar to their tank-type counterparts. Water, gas, and electrical connections are nearly identical to tank-type units. Multiple circuits and heavier wire may be necessary for electrical models due to the higher instantaneous current draw. Physically, the units are usually hung on the wall.
For point of use units, they are often installed under sinks, in closets, or in other locations where they can be accessed. Typically electrical units are used for these installations, and given their smaller size, can often operate off of a standard outlet. In this case, the plumbing must be designed and installed with the hot water line for the room separated from the whole-house hot water system.
Tankless water heaters provide hot water at a preset temperature when needed without storage, thereby reducing or eliminating standby losses. They can also be used for supplementary heat, such as a booster to a solar hot water system, or to meet all hot water needs.
Tankless water heaters can employ electric, gas, or propane heating device that is activated by the flow of water. Once activated, the heater provides a constant supply of hot water. The maximum flow rate at a desired temperature will be determined by the capacity of the heater.
Gas tankless water heaters typically have larger capacities than electric tankless water heaters.
Large units for whole house water heating use are located centrally in the house.
Tankless water heaters are rated by the maximum flow rate at which a desired temperature rise is met. Special features may allow the user to set the delivery temperature. Efficiency is higher than an equivalent tank type water heater because standby losses are virtually eliminated. Residential gas models are available that can heat more than five gallons per minute by 60°F, generally more than enough for two showers to be run simultaneously. Whole house electric units typically have a capacity closer to three gallons per minute.
DESIGN & SETUP - New construction is the best time to introduce tank- less water heaters to maximize the benefits & minimize initial cost. Heaters can be centrally located in the house to minimize hot water runs.
Many gas tankless manufacturers recommend a direct vent – this will bring in fresh air from outside for combustion and vent the flue gas using a blower through a side wall.
INITIAL COSTS - Installation costs of tankless water heaters are from 2-4 times higher than tank-type water heaters. Accordingly:
- 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 models.
- 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 comparable 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.
Whole-house tankless water heaters are more expensive than current tank systems except when comparing 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 up to $1200 for a gas-fired unit that delivers 5 gallons per minute. Typically, the more hot water the unit produces, the more it will cost.
OPERATING COSTS - Electric tankless water heaters generally cost 10-20% ($40-80/yr) less to operate than comparable tank-type water heaters. Gas savings may be about 20-40% ($50-$100/yr). Equipment life of tankless water heaters is 20 years, compared with between 10 and 15 years for tank-type water heaters.
BUILDING 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 mfg's installation requirements and should be followed precisely.
INSTALLATION of tankless water heaters is very similar to their tank-type counterparts. Water, gas, and electrical connections are nearly identical to tank-type units. Multiple circuits and heavier wire may be necessary for electrical models due to the higher instantaneous current draw. Physically, the units are usually hung on the wall.
For point of use units, they are often installed under sinks, in closets, or in other locations where they can be accessed. Typically electrical units are used for these installations, and given their smaller size, can often operate off of a standard outlet. In this case, the plumbing must be designed and installed with the hot water line for the room separated from the whole-house hot water system.