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HVAC School

In order to calcuate the compressor capacity (in cubuc feet per minute) you need two pieces of information. The first is the mass flow rate of the system, in pounds per minute, and the other, as you mentioned, is the specific volume. THe specific volume you are looking for, though, is the specific volume of the refrigerant at the inlet of the compressor.

First, the mass flow rate of the system is a function of the compressor horsepower and the heat of work generated during the compression process. You would need to plot the system on a pressure-enthalpy chart to obtain this information.

The specific volume is also found on the pressure-enthalpy diagram and is located at the point where the compressor inlet temperature and the evaporator saturation temperature cross. For an R-22 air conditioning system operating at desikgn conditions with reasonable suction line superheat, the specific volume is about 0.7.

Since the mass flow rate is in lb/min and the specific volume is in cubic feet/lb, multiplying the two gives you cubic feet/min, which is the volumetric capacity of the compressor.

THere will be a new book out soon that covers all of these goodies and a whole lot more so, if you drop me an e-mail, I will keep you posted. In addition, I will be conducting a series of pressure-enthalpy workshops in the coming months. So, in your e-mail, be sure to include your geographic lcation so I can keep you informed about dates and locations in your area.

Hope this info helps.

Comments

  • Biged
    Biged Member Posts: 117
    HVAC School

    HI YOU ALL, I'm looking for a school in or around Boston that teaches Hvac. I did a course 5 years ago but stayed with the oil and gas heating side of the trade but now I want to combine all three. I'm not sure I need to do over everthing but I would definitely need strong hands on and trouble shooting.
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    Long Island

    Is Suffolk County, NY too long of a commute?

    www.sunysuffolk.edu
  • ed wallace
    ed wallace Member Posts: 1,613
    HVAC school

    best school in boston area is the Peterson school 2 schools in Woburn and Westwood

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  • Rookie_3
    Rookie_3 Member Posts: 244


    Hey Ed, did you go To Peterson? I went to the Woburn school
    a few years ago. I took the HVAC-R, Oil, & Gas courses.
    I got into the HVAC and Oil big time, couldn't get enough. Got licensed in Oil and got my Universal. The heating season was just taking off and it seemed like everyone was complaining that they couldn't find Techs. I think I tried every company within a reasonable distance and couldn't get a damn shot anything to do with Oil. Nobody was interested at what you know, just how long you have been doing it.
    No experience, no job. I picked up some customers on my own but not enough to keep going. I ended up getting picked up for an AC job in the middle of the winter. (Heat pumps)
    If you went to Peterson and had one of the same instructors
    that I had you can recall what he always said.
    H-V-A-C......Highly-Visable-Always-Clean. He taught some good theory but that wasn't one of them. I've been not so visable in some dirty attics to prove that one wrong.LOL

    Dan...AKA Rookie from the above wall
  • Biged
    Biged Member Posts: 117


    I did go to Peterson Woburn about 5 years ago. and I did learn a lot but never did any hvac once I left school kinda stuck to oil. I started reading my books again and a lot has come back to me but I just wanted a refresher course.
  • steve_93
    steve_93 Member Posts: 37


    Just graduated from NEFI's AC course...

    I thought it was good and learned alot. Hands on with residential ac units...( hi Kenny) something Peterson doesn't offer, or at least didn't 3 years ago when I went.

    Don't know about NEFI's oil class, but I can tell you that the lab was unbelievable, with all the common and not so common boilers to work on. Peterson didn't have anything like this!

    Peterson's oil classroom I thought was exceptional( took the State test in 10 minutes and got a 94, thanks Mike), but the lab had little to be desired( sorry Mike).

    The gas class and lab was very good in Peterson.

    Went to Peterson for oil, gas, and HVAC at their Woburn location.
  • Ken D.
    Ken D. Member Posts: 836
    School

    Is there a local chapter of the RSES in your area? They generally have HVAC/R schools available. Try their HQ in DesPlaines,Illinois.
  • Rookie_3
    Rookie_3 Member Posts: 244


    Got to agree with you Steve, Mike has oil running through his veins and knows how to teach it and after 16 weeks with him the state exam look like preschool. I don't agree with you on the Gas course. Maybe because I was there during Hockey season and everybody got to go home early to see the games Maybe the fact that you got the answers before every exam and if you still failed you could take it again. A Peterson certificate doesn't go far on a Keyspan
    application and that doesn't say too much since Keyspan employees are moonlighting as Peterson instructors.
    Sorry, they are very nice guys but somebody had to say it!!!

    Dan
  • Biged
    Biged Member Posts: 117


    that's the reason I did over my gas course at NEFI
  • Rookie_3
    Rookie_3 Member Posts: 244


    BigEd, is Watertown the only location NEFI has?

    Dan
  • ed wallace
    ed wallace Member Posts: 1,613
    schools

    > BigEd, is Watertown the only location NEFI

    > has?

    >

    > Dan



    nefis main school is in watertown they do offer courses in rhode island just dont know where

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  • steve_93
    steve_93 Member Posts: 37
    gas

    Can't disagree with you.

    Well as far as getting answers before the test??? I thought that's what classroom was for...

    Your right about getting to retake the test, but it doesn't mean it's not a good basics course.

    If you want more than basics I'd take some of Timmie's seminars.

    Do you have any knowledge about NEFI's program?
  • Biged
    Biged Member Posts: 117
    NEFI gas course

    is still in it's early stages but I learned more there than I did at the others "P" school. gas code was none exsistent, hands on was a joke even class room was unsatisfactory so I decided to go to NEFI. The instuctor, John was a Key Span training instuctor for I think 18 years plus he was in the field for years, so there is a lot of experiences to pass on.
  • Rookie_3
    Rookie_3 Member Posts: 244


    Steve, I don't know too much about what NEFI has to offer, just digging for info now on it. I was looking at some of Timmie's training but most seem to be one complete area a day rather than a course type of program. Also I think most of his are in R.I. and I am in Northeastern MA making a 24 hr. day for work, school, study, and commuting a little tight. I'm sure you got some basic Gas knowledge at Peterson, I got some basics also but I wouldn't hire myself or anyone else based on a 100% grade average from that course. I know class is all about learning the answers before the exam and I worded that wrong, we actually had the exact questions and answers to the test. We would go to the class prior to the actual class that the test was on for a review and then go home when the review was done. The class usually was shorter than the ride to get there. I guess that gave us time to memorize the test.LOL!!

    Dan
  • Hvactech58
    Hvactech58 Member Posts: 4
    specific volume of a system

    For diagnostic purposes, how do you determine the specific volume of a system ; given the fact that the specific volume decreases as the temperature and pressure of a refrigerant (ie.R-22) increases. In other words, where do I acquire the temperature reading necessary to utilize a Saturated Liquid and Saturated Vapor Properties Chart in order to calculate the capacity of a compressor et-al?
  • steve_93
    steve_93 Member Posts: 37


    Wow... we didn't get the questions in advance.

    Actually ,there were maybe a couple of days when we went home 30 minutes early... but that was few.

  • We also offer a 240 hour

    course on gas set up in two phases with a payment plan that makes it easier to work with.

    Once you finish the 240 hour course there are three more phases that will end up giving you a total of 360 hours.

    We started this class that we are now running in June and it will run to June 2006. It is night course running from 6:00 PM until 10PM one night a week for now and then going to two nights after Jan 1.

    As to people from Mass, NH, Maine, CT and Vermont attending we do not have any problem. Our one week long seminars are well attended by folks from as far as California, Wisconsin, Ohio, Pennsylvania and etc. So a drive from eastern Mass is no big deal.

    If you have any interest just call me at 401-437-0557 or e-mail at [email protected]

    I look forward to serving you.
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