Question: I want to install an electric wall register. I have a choice of a Cadet Register Plus multiwatt unit (700, 900, 1600 watts) or a single-watt 2000-watt unit. Which would be the best from an energy-efficiency standpoint? How would the multiwatt unit work? Does it step up automatically or do you need to manually adjust when using a wall thermostat? Thanks for your help, from Hal A.
Mr. Tight Watt asked Curt Klaassen, formerly with the Iowa Energy Center, to answer Hal’s question.
Answer: Choices, choices!!! It appears that you have a choice in the watts or heat output capacity for the unit. From an energy-efficiency standpoint, all electric resistance heaters are considered to be 100 percent efficient. The best choice would be the unit that most closely matches the heat loss of the room in which it is installed. An undersized unit would not heat the room adequately on the coldest days, while an oversized unit would make it cycle on and off more frequently, especially in milder weather. Right-sized is most energy efficient.
The particular multiwatt unit described has two heating elements: a low-capacity element at 700 watts; a high-capacity element at 900 watts; and a total capacity of 1,600 watts with both elements operating. The way it is wired when installed determines the watt capacity and therefore the heat output of the unit. There is no manual adjustment or switch to change the watt capacity of the multiwatt unit described. A wall thermostat only turns the unit on and off and would not automatically step up the unit capacity. However, it should be possible to rewire the multiwatt unit to a different capacity should the original capacity selection not be appropriate—that may help out with the right-sizing situation.
It is important to install the heater in strict accordance with the manufacturer’s instructions, remembering to maintain airflow and clearances to combustible materials (see "For more information," below).
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