Electric water heaters are most commonly used where gas service is unavailable locally or where topography or other factors dictate that the gasoline supply line cannot be economically run to the house from the main gas line. While high efficiency electric heaters convert electric current into heat with less energy loss than petrol combustion, the higher cost of electricity versus natural gas in many regions means that a higher efficiency electric heater will still cost more to work with. Deciding on the best high efficiency electric water heater for your needs involves comparing several facets.
The Energy Factor (EF) evaluation of a water heater inhabits the efficiency of the heater in converting electrical energy to warm water. The higher the EF, the more efficient the heater. Conventional efficiency electric water heaters may have EF ratings as low as .75. High efficiency water heaters are those with EF ratings of .90 or over. For storage tank water heaters, .95 is generally the top limit. EF is affected by how effectively the heater moves heat energy into the water, the amount of heat lost from the storage tank since the reservoir of heated water waits to be used and the heat loss as water cools through the internal passages in the water heater as well as the inlet/outlet pipes.
An electric water heater’s capacity should match your home’s demand for hot water. The basis of comparison for heaters that use a conventional storage tank is that the First Hour rating. Usually located on the yellow EnergyGuide sticker attached to a heater, the First Hour rating represents the gallons of warm water a heater may create in one hour at peak demand, starting with a tank full of water warmed to the thermostat temperature setting. If the heater’s Initial Hour score is less than your household peak demand, you may wind up taking a cold shower if you are the last one in line. It’s usually best to choose a heater with an Initial Hour score about 10 percent above the summit household demand to allow for future gain in the amount of occupants or other changes that would increase your consumption of warm water.
Tankless Electric Heaters
Electric water heaters are also accessible as tankless, demand-type versions. These components utilize electric coils to instantaneously heat the flow of water on-demand, since you use this, nor integrate a tank to store hot water. Tankless heaters offer higher efficacy because there is not any heat loss because of water cooling at the storage tank. But a tankless heater must be able to heat the water as fast as you can use it or you will experience water that falls below the desired temperature. The tankless heater’s capacity to fulfill that demand is expressed by means of a specification called temperature rise — the quantity of heat in degrees it can create at a specified gallons-per-hour (gph) flow rate. If the temperature of cold water entering the heater is 50 degrees and the desired hot water temperature is 120 degrees, then the heater needs to generate at least a 70 degree temperature increase at a gph flow rate sufficient to fulfill the requirements of the household.
Hybrid water heaters use a heat pump to heat water along with electrical resistance to give additional heat. A heat pump extracts latent heat in the surrounding air and transfers it into the water in the tank via a heat exchanger. Because the heat pump alone may not be able to create sufficient heat to deliver the water into the usual standard of 120 degrees, electrical resistance coils inside the cylinder activate to extend the further temperature increase. Due to the efficiency of the heat pump, hybrid components usually use about 60 percent less electricity than all-electric water heaters and also have an EF rating over 2.00. But a hybrid unit is significantly taller than a typical water heater and many not fit in an present water heater closet. Moreover, the heat pump exhausts large quantities of cold air which must be vented in the home.