Controls

Question 1

Select 4 switches that are activated in response to change in temperature

Answer 1

thermostat switch, fan switch, high-limit and flame roll-out

Question 2

how man contacts are on a SPDT

Answer 2

Two

Question 3

Switches can be operated by hand or they can be activated by changes in

Answer 3

pressure,magnetism,temperature and fluid movement

Question 4

what is the operating principle of bimetal switches

Answer 4

different coeffient of expansion

Question 5

select the property a spiral bimetal in a mechanical thermostat to tip the murcury and complete the circuit

Answer 5

expansion and contraction

Question 6

what is the prupose of a heat anticipator

Answer 6

avoid overshooting room temperature

Question 7

what do the numbers on a heat anticipator indicate

Answer 7

amperage

Question 8

when is the heat anticipator energized

Answer 8

when the thermostat closes its contacts

Question 9

is a cooling anticipator wired in series or pararrel to the thermostat

Answer 9

parallel

Question 10

what is the typical setting for a high limit aquastat

Answer 10

200F

Question 11

which method of mountain a aquastat uses an immersion well

Answer 11

Direct

Question 12

what term is used to describe the pressure switch that controls the operation of a steam boiler

Answer 12

Pressuretrol

Question 13

gas switches are required to be installed on a burner system that exceeds

Answer 13

.5psi according to b149.3 gas code

Question 14

how many sensing tubes would you expect to see on a pressure switch that is connected to a draft inducer fan serving a single stage conventional appliance

Answer 14

1

Question 15

what are the two basic types of low water cut offs

Answer 15

float and probe

Question 16

why would a contactor be used rather than a standard relay

Answer 16

higher amperage

Question 17

why do vent dampeners also include a end switch

Answer 17

to prove the damper is fully open before igniting the burners

Question 18

when the zone valve motor is energized does current immediatly flow through the end switch

Answer 18

NO, the valve must be fully open to close the endswitch

Question 19

what term is used to describe the process of generating electricity in the secondary windings of the transformer

Answer 19

induction

Question 20

what would be the VA rating of 120/24v transformer that is able to deliver 1.667Amps

Answer 20

40.008 24x1.667=40.008

Question 21

which of the following would be classified as an normally open switch flame-roll out,automatic fan switch, high limit switch, high limit pressure switch

Answer 21

Automatic fan switch