Common Types of Residential Heating and Cooling Systems

Question 1

What are three advantages of electric space heating?

Answer 1

• Clean
• Efficient
• Self-contained
• Long life
• Low maintenance

Question 2

What is the usual “watts per unit length” rating of standard density baseboard heaters?

Answer 2

820 W/m (250W/ft)

Question 3

Where in a room should baseboard heaters be mounted?

Answer 3

at floor level, centred along the walls, and near areas of high heat loss (such as under windows)

Question 4

What type of heater is normally installed at ceiling height?

Answer 4

Unit heaters (either vertical or horizontal air projection types)

Question 5

Residential electric furnaces are usually available in both single-phase and three-phase ratings from _____kW to _____kW

Answer 5

5kW, 40kW

Question 6

What type of electric heater unit can be used with certain oil-fired, forced-air furnaces?

Answer 6

Plenum heaters

Question 7

What are two applications for heating cable sets?

Answer 7

• Radiant space heating (floor or ceiling)
• Driveway/sidewalk ice melting
• Freeze protection on pipes

Question 8

Residential water heaters are commonly available in _____kW and ______kW ratings

Answer 8

3kW, 4.5kW

Question 9

What are the three types of thermostats commonly used in residential space heating applications?

Answer 9

• Line-voltage
• Low-voltage
• Electronic

Question 10

If a heat lamp using a medium-base lamp holder is installed in a residential bathroom, does it have to be on a separate heating branch circuit?

Answer 10

No; CEC Rule 62-108(3)

Question 11

What size conductor would you need to supply a 3kW baseboard heater fed by a 240V circuit?

Answer 11

AWG #12. The calculated load requires a 20A overcorrect device. Therefore, the wire size must be increased from #14 AWG

Question 12

What is the maximum setting of overcorrect device allowed to protect branch circuit wiring supplying two or more residential baseboard heaters?

Answer 12

30A; CEC Rule 62-114(2)

Question 13

Is it necessary that a thermostat with a marked OFF position disconnect all ungrounded conductors in the circuit?

Answer 13

Yes; CEC Rule 62-118(2)

Question 14

Why is it not permissible to shorten the heating portion of a series heating cable set?

Answer 14

The series resistance would be reduced, resulting in increased current and possible overheating (fire hazard); CEC Rule 62-122(1)

Question 15

Indoor heating cable sets that are to be embedded in concrete shall beat the designation Type _______

Answer 15

1B; CEC Rule 62-124(1) and Table 60

Question 16

Where are the supply registers of a forced-air furnace normally located?

Answer 16

Around the perimeter of each room, preferably in front of areas of high heat loss

Question 17

What is the purpose of the heat exchanger in a gas-fired furnace?

Answer 17

To separate the products of combustion from the circulated air

Question 18

The typical efficiency of a gas-fired furnace is between ___% and ___%

Answer 18

70%, 80%

Question 19

How many conductors are commonly needed between the furnace and the room thermostat? What is the magnitude of the voltage that they carry?

Answer 19

Two or three; 24V

Question 20

Which does the room thermostat control directly, the gas valve or the blower motor?

Answer 20

The gas valve

Question 21

After the thermostat contacts open, which shuts off first, the blower motor or the gas burner?

Answer 21

The gas burner

Question 22

What is the purpose of the anticipator resistor in the room thermostat?

Answer 22

To limit the set-point overshoot to an acceptable level

Question 23

What is the purpose of the thermocouple? Is one always necessary?

Answer 23

When heated, the thermocouple generates a small current that holds the gas safety valve open. A thermocouple is not required on units equipped with electronic spark ignition

Question 24

List two conditions that may cause overheating of the heat exchanger

Answer 24

• Room thermostat contacts stuck closed
• Blower does not run
• Insufficient air flow

Question 25

What prevents the heat exchanger from overheating?

Answer 25

The high limit overheat safety thermostat will close the main gas valve

Question 26

What are the typical settings for the blower control/overheat safety thermostat?

Answer 26

• Blower OFF at 32°C (90°F)
• Blower ON at 54°C (130°F)
• High limit OFF at 104°C (220°F)

Question 27

Where should an electronic air cleaner be installed on a furnace?

Answer 27

In the return air duct, preferably downstream of the standard filter

Question 28

Describe how an electronic air cleaner filters the air

Answer 28

The ionizing section charges the dust particles which are then attracted to the charged collection plates

Question 29

Why should the electronic air cleaner be interlocked with the blower motor?

Answer 29

To prevent the accumulation of ozone that can occur if the cleaner is energized and has no air flowing through it