All rights reserved. Printed in the United States of America. Page 4 a word that matches the picture (Listening Comprehension standard score = 84) and generate words within a category, describe scenes, and give directions (Oral Expression standard score = 83).
The power is supplied by a transformer, and when the thermostat makes contact between the 24 volt power and one or two of the other wires, a relay back at the heating/cooling unit activates the corresponding heat/fan/cool function of the unit(s).
posts:10944. votes: 80. if it's a modern thermostat you would want to save the settings in a power outage and the current draw is so low that a 9V will last a long time. not only that you don't need to include a (AC-to-DC) transformer in the thermostat. it also means the thermostat can be screwed into the wall anywhere that you want to poke a hole for the control wire and won't require a junction box or an electrician to install it.