Or is there? This saying is an old adage in our industry to let the technician know that the refirgerant charge is "all set". You see, there must be a steady stream of liquid to the metering device for it to function properly. For sake of conversation, let's use the TXV. In order for most TXV's to throttle and correctly maintain the desired Superheat, there must be a minimum of 2F of subcooled liquid at the valve (not where it is measured, near the condenser). If the liquid were to flash off ahead of the valve, destruction to the TXV may occur. So, some old timer along the way figured he would look into the sight glass (what we install in residential air-conditioners this day and age are moisture indicators), and determine if there was a steady stream of liquid, or in other words: "No Bubble, No Troubles!". For years, this method combined with "beer can cold", or "sweating back to the compressor" were used to determine the refrigerant charge was 'close enough'. Those that know me know that I speak from experience here, I have tried them all!
What we were missing was the fact we were overcharging systems, significantly. Sometimes to the point of slugging compressors, particularly with fixed orifice systems. Having a steady stream of liquid does not mean the refrigerant charge is correct! I know, I am preaching to the choir here. You see, if you are reading my blog than you care enough to learn how to do things right. I am sure you have picked up an installation manual recently and actually flipped through it, instead of kneeling on it and tossing it into the trash! If you have, you will notice that no where in these books does it read, "No Bubbles, No troubles!" If it were that simple, than they would have put it into the start-up procedure. Do me a favor: stop wasting energy and killing compressors, okay? Take the extra ten minutes to measure the Superheat and Subcooling on the system, and verify they are within manufacturer specs. Believe me, you will have less warrantied labor work where you make zero profit replacing compressors!

http://excessair.blogspot.com/p/blog-page_23.html

Views: 85

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Profile IconWes Anderson, Jean-Paul and Bryan joined Home Energy Pros
17 hours ago
Dennis Heidner commented on Dale Stephens's blog post LED Lighting 24-month update 18,240 hours & counting
"Dale, good write up. For the landscaping bulbs,  if they had been T3 12V wedge bulbs,  I…"
yesterday
Brett Little commented on Tom White's video
Thumbnail

The Future of Housing - And How Airtightness Can Help

"It's very true! So many people and contractors have tons of insulated attics but no air seal…"
yesterday
Chris Leach replied to Richard Beyer's discussion "The Dangers of Using Spray Foam Insulation"
"The problems will surface soon enough . Why don't we take a second look at this over rated…"
yesterday
Don Fitchett commented on Tom White's video
yesterday
tedkidd replied to Bob Blanchette's discussion How does Cycles Per Hour affect real world AFUE?
"Want to spot a simpleton? It's a guy who thinks EE and comfort are disconnected.  Want…"
yesterday
tedkidd commented on Tom White's blog post Clean Energy Works Oregon: Total Home Performance
"Nice post Tom! I really like how he puts that. Leveraging interests so they can optimize…"
yesterday
Kent Mitchell commented on Tom White's blog post Clean Energy Works Oregon: Total Home Performance
"As a contractor in the region - we frequently wonder how/why you can be a non-profit?  Oregon…"
yesterday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service