Bureaucrat, staff, administrator
4,335
edits
Changes
→Energy Efficiency
==== Energy Efficiency ====
Although the unit efficiency of a demand heater is only somewhat better than a tanked heater, the tanked heater must operate continuously while the demand heater operates intermittently; thus consuming less energy overall.On average, a tankless water heater uses 25 to 50 percent less energy than a storage water heater.<ref>https://www.householdwatersystems.com/advantage-tankless-water-heater/</ref>
=== Point of Use ===
* A tankless-heater system designed to minimize the electrical load can be designed.
A large and well insulated water tank is pre-heated by a solar collector and/or the engine. A solar collector could be mounted on the pilothouse roof. Flat panels are easy to fabricate and more cost-effective than evacuated tubesbut tubes track the sun better and are more energy efficient. <ref>http://www.apricus.com/html/solar_collector.htm</ref> Temperatures in the tank can run over 180°F, so a tempering valve mixes in cold water on the output side to adjust the temperature to 120°F. A small tankless heater only kicks in when the temperature drops below 120°F. The pump circulates a 50:50 water-glycol solution to prevent freezing in cold climates. It doesn’t operate at night.
With a typical load of 3.8 kW, a continuous operation hot-water tank is a better choice for a smaller boat. Despite its lesser energy efficiency, it has less impact on the electrical system.
Both the continuous-operation tank and the heat-exchanger tank with AC backup share the disadvantage of larger size, overall energy inefficiency when using electricity, and the possibility of running out of hot water. In addition, the heat-exchanger model requires a more complex layout. The tankless design with solar collector is even more complex. In both cases, the complexity is mainly in mechanical plumbing.
== References ==
[[Category:FreshwaterSystems]]