Controls Ft. T Frank

Question 1

What does a closed loop control circuit do

Answer 1

Uses feedback to make control system automated

Question 2

Purpose of an automatic gas valve

Answer 2

• comfort
• safely
• economy
• convenient

Question 3

What does a pressure transducer sense?

Answer 3

Pressure than coverts to electrical signal

Question 4

On a A19 temp controller feat position is B in?

Answer 4

Closes on a rise in temp heating

Question 5

What does an anticipator do

Answer 5

Creates false load to prevent overshoot

Question 6

Like voltage thermostat can be temporarily used in a millivolt application?

Answer 6

Yes

Question 7

What’s in a mercury bulb thermostat

Answer 7

Bimetal coil and contactor

-must be carful levelled

Question 8

Strip type sensor is used for what

Answer 8

Electric baseboard heating

- no anticipator

Question 9

Natural gas “WC?

Answer 9

3.5”

Question 10

How much power does a thermocouple make

Answer 10

30mv DC

Question 11

What kind of power does flame rectification create?

Answer 11

DC micro amps

Question 12

What is an anticipator in heating

Answer 12

A resistance wire in series with thermostat contacts

Question 13

In heating is anticipator energized in the off cycle

Answer 13

No

Question 14

Thermistor change in temp=

Answer 14

Change in resistance

Negative temperature

Question 15

2nd Series if events for hearing

Answer 15

Pre purge

Question 16

What makes a spiral sensing element more accurate

Answer 16

Increase length

Question 17

Setting at LPC how long do you watch it for?

What temp can it not go below

Answer 17

2 cycles

33.5F

Question 18

Direct Spark or hot surface igniter use flame rectification?

Answer 18

Yes

Question 19

Is a resistor temp detector more accurate than a thermistor?

Answer 19

Yes

Can be positive or negative

Question 20

A-19 is snap acting? Why?

Answer 20

Yes to avoid arking

Question 21

How is an anticipator wired in a cooling cycle

Answer 21

In parallel

Question 22

When does a constant cut in control cut in?

Answer 22

38F or 41F

Question 23

Combination gas valve, must must be held open manually when lightning pilot?

Answer 23

Yes

Question 24

When does the fan shut off

Answer 24

90-100F

Question 25

Igniter warm up period?

Answer 25

17 seconds

Question 26

Do millivolt thermostats have anticipators?

Answer 26

No draws too much voltage drop

Question 27

What does open loop mean?

Answer 27

No feed back | Operates by time

Question 28

Power goes from where to where in furnace ac control

Answer 28

In from R to Y though the CC than to C

Question 29

Disadvantage of pump down?

Answer 29

Compressor could short cycle | Ex. Leaking solenoid, improperly set LPC

Question 30

Dry bulb is effected by Humidity Air movement Radiation

Answer 30

Yes

Question 31

When does the fan turn on?

Answer 31

120-140F

Question 32

How long does inducer motor run after blower off?

Answer 32

15 seconds

Question 33

Call for heat terminals

Answer 33

R and W close

Question 34

Approximate settings if a high limit switch in the high voltage circuit?

Answer 34

180-200F

Question 35

Blower off delay what terminals?

Answer 35

Cr and W open

Question 36

Combination gas valve, how much power does the main valve need?

Answer 36

24VAC

Question 37

What is LVT cable

Answer 37

Extra low voltage cable | For thermostat wiring

Question 38

Why is a jumper factory installed

Answer 38

When cooling and heating use same control voltage

Question 39

Advantages of pump down?

Answer 39

- No flooding the comp | - very good liquid refrigerant control

Question 40

I’m cooling when is the anticipator energized?

Answer 40

On the off cycle

Question 41

Combination gas valve, what is powers by the thermocouple

Answer 41

- safety - power unit - pilot start

Question 42

What’s in a combination gas valve?

Answer 42

- Regulator - safety valve - power unit - main gas valve - manual gas shut off

Question 43

What temp does AHRAE recommend for cooling

Answer 43

75F for cooling

Question 44

Does power from a thermocouple open the pilot valve?

Answer 44

No only holds it open

Question 45

What class of transformer do most furnaces have?

Answer 45

Class 2

Question 46

With a F-140-20 disk type overload what does the 140 mean and 20

Answer 46

140 is cut out | 20 is differential cut in

Question 47

Checking volts in electrical circuit

Answer 47

Power is on and Meter in parallel

Question 48

Motor starters and contractors are different because

Answer 48

Motor starters have overloads

Question 49

Ad stages of hot water heating

Answer 49

Less space | Less air movement

Question 50

Hot water disadvantages

Answer 50

No ventilation | No air filtration/humidity control

Question 51

What so zone thermostats control

Answer 51

A pump or valve

Question 52

On mid efficient furnaces they need to maintain return water temp of ______ to prevent condensation

Answer 52

130

Question 53

Hot water, .43 psi pressure drop for upwards piping

Answer 53

Yes

Question 54

Can a mop txv and a cpr be together

Answer 54

No

Question 55

High limit is set at what fir hot water application

Answer 55

210F

Question 56

Hot water uses float type and electric for

Answer 56

Proving water flow and low water cut out

Question 57

Hot water expansion tank w no bladder is called a

Answer 57

Compression tank

Question 58

Make up water regulator is set between

Answer 58

10-25 Psi

Question 59

Can zone valves be power open abs power closed

Answer 59

Yes

Question 60

Transformer can only be loaded to

Answer 60

80%