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  1. #1
    Join Date
    Jul 2011
    Location
    Connecticut
    Posts
    4

    Newbie Needs Help

    Hi All! I am new to this site and fairly new to HVAC as a whole. I am, by trade, a mechanical engineer, and hold degrees in both mechanical and electrical engineering. Although I have not performed a great deal of work on air conditioning systems, I fully understand how one works, as well as both the physical and mathematical principles at work. I am also very familiar with the various equipment, refrigerants, etc., etc. used in the industry.

    In the past, I have assisted a close friend (an HVAC technician) installing, repairing, and troubleshooting air conditioning systems on his side jobs. I am now ready to tackle my first solo condenser replacement, and need some advice regarding tools. I have already acquired the refrigerant, equipment, and miscellaneous supplies.

    First and foremost, what tools are required for this task? Which are best, digital or analog manifold gauges? What brand does everyone prefer? How about the digital manifolds that also calculate superheat/subcooling? Any help would be GREATLY appreciated!

  2. #2
    Join Date
    Sep 2009
    Location
    Stumptown,USA
    Posts
    1,250
    The most important tool is about 10 years of "the school of hard knocks". If I were you I would have my close friend come with me the first couple of "solo" jobs to watch and point out safety concerns. Have him let you do everything, just let him speak up if you are about to hurt yourself. If you don't know what tools are required for this task, you are not ready to fly solo. Torches that can explode with only 15 psi impact, refrigerant that can cause frostbite, voltages that can kill. I have been tinkering with bicycles and cars since I was 10 years old, I have worked as a repairman since I was 18 years old and am very careful by nature, I have been to the emergency room 4 times in 39 years and electrical shocks too many to count, once with 4000 volts, once from a capacitor with 2000 volts, that time my heart stopped. Please be careful and get help if you need it, we don't want any body to get hurt.
    Challenge yourself, take the CM test --- Certificate Member since 2004 ---Join RSES ---the HVAC/R training authority ---www.rses.org

  3. #3
    Join Date
    Jul 2011
    Location
    Connecticut
    Posts
    4
    Quote Originally Posted by Paul Bee View Post
    voltages that can kill.
    Current (amperes) kills. Voltage does not. An ordinary static shock from dragging your feet on a carpet produces thousands of volts, but does not kill you. Anyone second me?

  4. #4
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
    Posts
    1,133
    Quote Originally Posted by HandyMan92 View Post
    Current (amperes) kills. Voltage does not. An ordinary static shock from dragging your feet on a carpet produces thousands of volts, but does not kill you. Anyone second me?
    Sort of. Voltage can cause your heart to beat out of rhythm leading to death. Causes the frequency to change which leads to the problems, and that is a voltage thing, not an amp thing. IIRC, the human body operates on a roughly 59-60hz frequency.

    Usually though amps are the thingees that do stuff like knock a chunk out of your hip and butt as big as two fist, like happened to a coworker of mine when his ladder got hit by a overhead transmission line.

    But knowledge from a book doesn't translate to knowledge in your hands. I'd second the idea of having your friend accompany you, both for safety and also to be handy if you screw the pooch and stuff needs to be fixed right here, right now.

    In my area, unless the unit is attached to your home, you must be a paid employee of a licensed HVAC contractor or be the license holder yourself to change out a condenser unit. And a permit should be pulled and the change must be inspected. Going even further, unless you also carry the special electrical endorsement for HVAC contractors, a licensed electrician must pull a permit and re-wire the high voltage and have it inspected when changing a unit. There is considerable cost in doing this stuff that most folks don't realize. And even greater danger that they ignore also.

  5. #5
    Join Date
    Dec 2008
    Posts
    113
    Not related to OP, but a story that might save a life. A coworker of mine went to fix a rooftop unit that wasn't cooling. Make a long story short, the unit he was going to repair had a compressor short to ground, the ground for the unit itself was corroded and faulty. This rooftop was near another rooftop. The tech approached the broken unit and placed his hands on the top of that unit and the top of the adjacent unit, whose ground was perfectly fine. Current came from the disconnect, through the closed contactor, through a portion of the compressor windings, through the frame and casing of the unit, then through the tech and through the ground of the other unit. All he did was touch a unit, could have happened to any of us. I carry a voltage pen and I won't touch a thing without wiping that pen across it from now on and it saved me. Working on a temporary industrial air conditioner, I was hooking up the 4/0 cam cable and switched a line cable with the ground cable. I energized the unit, obviously oblivious to the fact I had put 480v to the entire frame of the unit, but I waved my voltage pen near and it went off. Took me a second, but I caught the error before anyone got hurt. I connect alot of cam cable and alot of temporary equipment, I guess I got complacent.

  6. #6
    Join Date
    Nov 2010
    Location
    Mt.Home AR
    Posts
    175
    To charge the unit u also need to understand super heat and sub cooling. Also the system needs a good vacuum pulled on it and so on..also is the evap matched for the condenser. list goes on..

  7. #7
    Join Date
    May 2007
    Location
    Michigan
    Posts
    311

    Toooools U need

    Degrees are great in the office!
    In the field for the job you are doing you need the following!

    Mechanical License to show you know what you are doing.
    Insurance if the equipment you put in burns the house down and kills people!
    CFC Certificate to verify you know not to vent refrigerant!

    All set now get at it!

  8. #8
    Join Date
    Jul 2011
    Location
    Connecticut
    Posts
    4
    After reading many of the replies, I will take your advice on having my licensed HVAC technician assist me. I will note, however, that the work will be performed at my house and not the house of a complete stranger.

    To answer the questions which were posed in some replies; Both the evaporator coil and condenser do match in all regards, and I am also quite adept at calculating superheat and sub cooling.

    On another note, I feel that people are assuming that I have little or no hands-on experience it any field simply because of my title. Before I earned all my degrees, I was a licensed/insured/ and bonded electrician who worked in the field everyday. After earning my degrees, I became the chief engineer at a firm which was involved with the construction of a nuclear power plant. There, I worked alongside other engineers doing to the actual (hands on) construction. The union electricians that were on the job reported only to me, and followed the orders which I gave them. Any work which they completed (as opposed to myself or other engineer) I was responsible for inspecting, texting, etc. In that position, I personally dealt with various equipment and system which the average electrician has never seen (not to mention, exponentially more dangerous than even the voltages found in a residential air conditioning unit).

    Back to my original post; I intentionally made my questions (and knowledge) seem very vague in a hope to let anybody who replied more or less "lead the way." Unfortunately, since the vagueness was interpreted as a lack of experience/skill/ ability, I will now be more specific:

    As my interest in the HVAC field has grown, I would like also like to expand and/or upgrade my collection of HVAC tools. At the moment, I am looking to purchase a 1) Manifold Gauge Set 2) Vacuum (Micron) Gauge 3) Thermometer/Apparatus used to calculate superheat/subcooling (I believe JB Industires makes a device which takes all of the measurements AND does the calculations for you!?) 4) Anything else which you think I may need.

    If possible, please let me know what brand and type you prefer for each item listed above, and/or what you think would suit me well. I have used my friend's basic set of JB Industries Manifold Gauges in the past, and have preferred them over my Yellow Jacket. However, from what I read, most pros here frown upon the JB Industries gauges. BTW....I have a brand new Yellow Jacket vacuum pump.

    I thank you all for your help and hope that I can get some honest, insightful answers from the pros in this forum despite my lack of 15 years of experience in the field...

  9. #9
    Join Date
    Sep 2007
    Posts
    171
    Quote Originally Posted by Paul Bee View Post
    The most important tool is about 10 years of "the school of hard knocks". If I were you I would have my close friend come with me the first couple of "solo" jobs to watch and point out safety concerns. Have him let you do everything, just let him speak up if you are about to hurt yourself. If you don't know what tools are required for this task, you are not ready to fly solo. Torches that can explode with only 15 psi impact, refrigerant that can cause frostbite, voltages that can kill. I have been tinkering with bicycles and cars since I was 10 years old, I have worked as a repairman since I was 18 years old and am very careful by nature, I have been to the emergency room 4 times in 39 years and electrical shocks too many to count, once with 4000 volts, once from a capacitor with 2000 volts, that time my heart stopped. Please be careful and get help if you need it, we don't want any body to get hurt.
    This short post covers a lot of important ground. I'll add that refrigerant spray to the eye and you are blind because you just froze and scarred your cornea.

  10. #10
    Join Date
    Jul 2011
    Location
    Connecticut
    Posts
    4
    Once again, thank you for reiterating the dangers associated with the task as well as the field as a whole. I fully understand them and the possible consequences that could occur as a result of inadequate knowledge and/or experience to perform the task. However, I was hoping that we could get back to the questions which I were in my most recent post....

  11. #11
    Join Date
    Jul 2001
    Location
    Canada
    Posts
    1,807
    Current (amperes) kills. Voltage does not, the RESULTING BURNS can !

  12. #12
    Join Date
    Sep 2010
    Location
    Chicago
    Posts
    218
    Quote Originally Posted by tbirdtbird View Post
    This short post covers a lot of important ground. I'll add that refrigerant spray to the eye and you are blind because you just froze and scarred your cornea.
    Goggles, some people think they are for wimps but I always wear them when connecting or disconnecting hoses or other tasks that require such protection.


    EPA 608 certified: Universal

  13. #13
    Handyman92, I was wondering if you completed your install? I see this post is a couple of months old. I was sort of in your shoes about five years ago. I am a Mechanical Engineer with a BSME that I earned in 1988 and have worked in a large automotive plant since then. That type of job has given me a lot of hands on opportunity in almost everything and also great resources for hobies. Examples we have an entire HVAC contract dept and most do residential installs on the side as well as an experienced test lab with Techs who have a lot of experience in engines that I could tap into when I was rebuilding jet skis. In 2006 I felt the same as you about replacing my upstairs unit which was undersized at 1.5 tons and wanted to learn more about HVAC. I took a 30 week course that met 3 hours per week at the local High School. It was subsidized by the school system for adults and only cost about $100 per ten weeks plus books and supplies. I am sure it was not as detailed as the 10K most HVAC Tech talk about but covered the basics for someone who already had my background. Afterward I contacted my local distributor and made arrangements to buy a EP608 kit and took and passed that to get the Freon purchase issue out of the way. I had a couple of estimates of $3000-$3500 to replace my unit. Instead I spent about $3000 but intead the breakdown was $1500 for buying the unit (Goodman Split) out of Florida and having it shipped to Tennessee, $500 on the class, books, and supplies, $1000 roughly on used eqquipment I purchased mostly off eBay. I bought an RDGA 510A Promax Recovery unit (same as the one my instructor had which retailed for about $850) for about $400, yellow jacket vacuum pump for about $80, basic yellow jacked gauges with needles for about $60, recovery tank for about $85, Yellow jacket vacuum gage for about $65, acetelyne turbo torch for about $75 and a few other basic supplies. I already had all the basic Fluke electrical equipment. Install went great and has been running for 5 years. Ended up taking the old 1.5 ton, insulating my unattached 800 sq ft garage, and installing it there so now I have a unit in my work shop. These guys are right, college is great for the basics but you need the hands on. One thing I remember is one night the instructor brought in a Hermatic compressor with the head cut off and took it entirely apart so we could see and handle the actual pieces. When I graduated from college all I knew about what an actual compressor looked like was that little diagram they used in the text books. Of course safety was one of the big topics of the course.

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