Cooling systems

Question 1

In residential units would a cooling system use the same ducting as a forced air system?

Answer 1

Yes. It would utilize the same blower fan as well.

Question 2

What is the purpose of the evaporator coil?

Answer 2

To pass low temperature refrigerant through and absorb heat from the inside air.

Question 3

Why is a compressor used in a cooling system?

Answer 3

So that the refrigerant can be passed easily through the pipes from high pressure to low pressure. The act of compressing also builds the temperature up quite high before sending the refrigerant through the condenser coil, this steep temperature difference with outside air enhances the heat loss from the refrigerant.

Question 4

What does hermetically sealed mean?

Answer 4

Welded shut. Cannot get into.

The motor operates in the atmosphere of the refrigerant.

Question 5

What is the purpose of the condenser?

Answer 5

To pass through hot high pressure refrigerant which will dissipate its heat and be blown away by the fan.

Question 6

What is another name for an evaporator?

Answer 6

An A coil.

Question 7

How does a refrigerant control valve often regulate itself?

Answer 7

Through the use of a liquid bulb and cap tube after the evaporator coil. A change in temperature will control how much cold refrigerant will be released.

Question 8

What is refrigerant?

Answer 8

The fluid which changes state rapidly in a small temperature gradient.

Question 9

What is the purpose of a cracnkcase heater?

Answer 9

To heat the refrigerant inside the compressor so that it stays in a vapour state to not mix with the oil.

Question 10

What is a dual pressurestat?

Answer 10

A combination low high pressure sensor for either side of the compressor.

Question 11

What is an automatic expansion valve?

Answer 11

A refrigerant control valve, which uses pressure to control itself.

Question 12

How far could a disconnecting means be located from a cooling system, if it was within sight?

Answer 12

3m, and readily accessible.

Question 13

If the cooling unit does not operate at all, where is the problem likely to be found?

Answer 13

In the electrical components.

Question 14

If the cooling unit functions, but does not cool, where is the problem likely to be found?

Answer 14

In the mechanical components.

Question 15

If combining an AC and heating system, what must be used to control the two fan speeds.

Answer 15

Either the pre existing ECB or a 24v relay with no/nc contacts.

Question 16

What type of wire should be used in the control circuit?

Answer 16

18awg or 16 awg (at 35m+ length).

Question 17

If you read full control voltage across a coil component, but it does not operate, should you check the device with your ohmmeter?

Answer 17

Yes, but only after shutting off the breaker for that branch circuit.

Question 18

What does a cooling system require to operate as a heat pump?

Answer 18

A four way reversing valve.

Question 19

Some devices only used with heat pumps are?

Answer 19

Double acting thermostat,
sequence timer,
defrost timer.

Question 20

What is a large limitation for heat pumps in calgary?

Answer 20

They would require an auxiliary heating source as the temp fluctuations are wide over seasons.

Question 21

How is a heat pump classified?

Answer 21

By the way it transfers heat.