Exam (elaborations)
NATE Air Conditioning and Heat Pump Exam 2023
- Course
- Institution
NATE Air Conditioning and Heat Pump Exam 2023
[Show more]
Content preview
NATE Air Conditioning and Heat PumpWhich of the following factors affects a customers level of comfort? - Answer- All of the above
A cooling load calculation estimates the sensible heat gain of the structure. The cooling-
only system should be within _____% of this calculated value. - Answer- +15%
The maximum sensible cooling capacity of a heat pump should be within ______% of the calculated sensible heat gain of a structure with a large heating load. - Answer- +25%
The combined output of a heatpump and its auxiliary heat should not exceed the calculated heat loss of a home by more than ____%. - Answer- 15%
What amount of auxiliary electronic heat is needed when the output of a heat pump on a
design day equals 18,800 Btuh and the heat loss of a home is 29,700 Btuh? - Answer- 3.2 kWh
The three processes that transfer heat energy are conduction, convection, and _________. - Answer- Radiation
Heat transfer that occurs when substances of different temperatures are in contact with each other is called _______. - Answer- conduction
What effect does raising the pressure in a sealed system have on refrigerant? - Answer-
The boiling point increases
What is the primary danger to people near an accidental refrigerant release or spill? - Answer- suffocation caused by the heavier refrigerant displacing oxygen in the air
The maximum temperature at which refrigerant may be stored is ______ F when the container is no more than ____% full of liquid by volume.; - Answer- 125 F, 80%
Boiling of the refrigerant occurs in which system component? - Answer- Evaporator Why is superheat necessary in a system that utilizes hermetic compressors - Answer- It ensures that dry vapor reaches the compressor so that mechanical damage does not occur
When the heat load on an evaporator increases, what is the effect on the system? - Answer- Suction pressure and discharge pressure both increase
What type of energy is transferred when work is done in the condenser? - Answer- Both
latent and sensible heat energy
What is the primary function performed by a thermal expansion valve? - Answer- It maintains the correct superheat in the suction vapor leaving the evaporator
Which component pumps refrigerant through the system and raises the vapor temperature? - Answer- compressor
How are hermetic compressor motors cooled? - Answer- With suction vapor drawn from
the evaporator
Heat pump compressors sometimes run hotter than compressors used in cooling-only units because heat pump compressors _____. - Answer- exhibit low refrigerant density at low suction pressures during the heating cycle
When is crankcase heat most needed? - Answer- When the compressor is off
Work done on the refrigerant in the condenser is transferred as ____. - Answer- Both sensible and latent heat
Why are more circuits needed in the outdoor coils used in heat pumps than in the condenser coils used in cooling-only units? - Answer- To keep the pressure drop across
the outdoor coil low
What is they typical water flow rate per ton of cooling for water-source heat pumps operating in closed loop systems? - Answer- 3.0 gpm per ton
What tool should be used to shorten a capillary tube? - Answer- A triangular or knife-
edge file
Which pressure in a TEV is opening pressure? - Answer- bulb pressure
What effect does a low refrigerant charge have on reversing valve operations? - Answer- It increases the chance that the reversing valve will not be able to transfer properly
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Gordones22. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79223 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now