Fundamentals: Charging A New System

September 28, 2002
/ Print / Reprints /
/ Text Size+
The work: A new A/C system installation.
The apprentice: Allen Charles Edwards (ACE) — first-year mechanic.
The technician: N. Arthur Thomas Egan (NATE) — 15-year HVACR veteran.

Nate and Ace are installing a new cooling system. They have followed the manufacturer’s instructions that came with the equipment. As required by the instructions, they have evacuated the system to 500 microns. The system is precharged with enough refrigerant for installation with a 15-foot line set. If the installation line set exceeds the precharged amount, they were instructed to add 1.2 ounces of refrigerant for every foot the line set exceeds the 15-foot limit.

NATE: “Ace, what do you think will be the best way to charge this system?”

ACE: “Nate, this is a new system, and I think we should charge the system using the weigh-in method. Then we can confirm the charge using the superheat method, since this is a capillary tube system.”

NATE: “Good, Ace. Tell me, how are we going to do this?”


ACE: “The first thing I’ll need to do is determine the maximum length of the tubing.”

The maximum length is:
a) 50 feet
b) 51 feet
c) 52 feet
d) 53 feet


ACE: “The next thing to calculate is the amount of tubing in excess of the manufacturer’s 15-foot line set allowance.”

What is the excess?
a) 30 feet
b) 37 feet
c) 43 feet
d) 52 feet


ACE: “Next, I will determine the amount of refrigerant that should be added to the system.”

How much refrigerant should be added?
a) 62.4 ounces
b) 51.6 ounces
c) 44.4 ounces
d) 36.0 ounces


ACE: “Then I will weigh in the proper amount of refrigerant.”

How much refrigerant will be weighed into the system?
a) 2 pounds, 4 ounces
b) 2 pounds, 12.4 ounces
c) 3 pounds, 3.6 ounces
d) 3 pounds, 14.4 ounces

NATE: “Ace, with the way you’re progressing you’ll be running your own service truck soon. Let’s get this system charged up and then we’ll confirm the charge.”

Please remember no question appearing in these articles is on a NATE exam. These questions and dialogue are my creation alone. The NATE Technical Committee does not review the article content, and the committee has the final decision for the use of a question on the tests.

Interpretation of codes, regulations, and standards comes from my experience as a technician and a contractor. Different jurisdictions have varying interpretations. The particular area a job is being done in will dictate which viewpoint is to be properly used.

I learn a lot from your commentary and try to incorporate information into the next article, so please continue to comment.

Patrick L. Murphy
Director of Technical Development

Answers: 1) c; 2) b; 3) c; 4) b.

Murphy is director of technical development, North American Technician Excellence (NATE). If you have any further questions or comments on this Fundamentals quiz, contact Murphy at (e-mail).

Publication date: 09/30/2002

Did you enjoy this article? Click here to subscribe to The NEWS Magazine

You must login or register in order to post a comment.



Image Galleries

2014 World Energy Engineering Congress

Scenes from the 2014 World Energy Engineering Congress in Washington, D.C.


NEWSMakers: Kari Arfstrom

Kari Arfstrom, executive director of the HVACR Workforce Development Foundation, talks about the upcoming HVACR & Mechanical Conference. Posted on Jan. 23.

More Podcasts


NEWS 01-26-15 cover

2015 January 26

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe

Regional Standards

With regional standards for a/c equipment going into effect in 2015, how do you think it will impact the industry?
View Results Poll Archive


2015 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research


Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.


Magazine image
Register today for complete access to Get full access to the latest features, Extra Edition, and more.


facebook icontwitter iconyoutube iconLinkedIn i con