charging my system and I have some questions
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  1. #1
    Join Date
    Dec 2011
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    Jacksonville, NC
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    charging my system and I have some questions

    I have an r22 heat pump package unit with design pressures of 150 on the low and 300 on the head. it's about 55 degrees outside, I have the inside temp set to 71. The low pressure is ranging from 50 to 60 psi (about 20 degrees) and head is ranging from 300 psi (115 degrees) to 350 psi (130 degrees). I was wondering what might be wrong. I don't have a sh or sc detector, but any help would be useful. It is heating the house, though the cycle seems rather short which, i would speculate, will drastically increase my electric bill

  2. #2
    Join Date
    May 2001
    Location
    carthage ms
    Posts
    629
    back away from the heat pump, if it is heating your house do not mess with it, if it is not heating your house, please call someone who has the knowledge to interpret the numbers you have given, this is something that unless you are qualified open up and work on you should not, as you could injure yourself and/or burn your house down
    The 2008 NATE TOP TECH!!!!!

  3. #3
    Join Date
    Dec 2011
    Location
    Jacksonville, NC
    Posts
    6
    ok i'll re-state my previous post. I am an apprentice hvac technician of 2 years, and I would like help on diagnosing the problem of this system. It wasn't heating the house earlier, and I charged the system with MY guages, and MY r22 freon that I bought because I have have my cfc certs. I just have not had much interaction with heat pumps, and am finding this confusing as to why there is no steady pressure, and why the suction pressure is so low compared to the design specs. also, can it even be diagnosed properly without sc or sh being calculated

  4. #4
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,812
    Quote Originally Posted by Impulse View Post
    I have an r22 heat pump package unit with design pressures of 150 on the low and 300 on the head. it's about 55 degrees outside, I have the inside temp set to 71. The low pressure is ranging from 50 to 60 psi (about 20 degrees) and head is ranging from 300 psi (115 degrees) to 350 psi (130 degrees). I was wondering what might be wrong. I don't have a sh or sc detector, but any help would be useful. It is heating the house, though the cycle seems rather short which, i would speculate, will drastically increase my electric bill

    What's a "sh or sc detector"? Ya know it's not a good idea to charge when it's 55 degrees?.....
    Give a man a fish, he will eat for a day. Teach a man to fish, he will eat for a lifetime.

    Give a man a capacitor, doesn't know what to do. Teach a man to install it, now he knows everything.

  5. #5
    Join Date
    May 2001
    Location
    carthage ms
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    629
    the design pressures and the operating pressures are two totally different things, there should be a charging chart on the machine, do not charge to the design pressures thats all im gonna say, and have probably already broken the no DIY rule!
    The 2008 NATE TOP TECH!!!!!

  6. #6
    Join Date
    Dec 2011
    Location
    Jacksonville, NC
    Posts
    6
    Quote Originally Posted by beshvac View Post
    What's a "sh or sc detector"? Ya know it's not a good idea to charge when it's 55 degrees?.....
    I don't have any device to measure sub cooling or super heat, just my manual guages. and I know it's not the best idea to charge when it's 55 degrees, but when a unit is running all night and can barely achieve 65 degrees, there was obviously a problem. I would have thought that the low pressure would be a little higher after I was done, but I guess that's the normal operating pressure of this unit. there is no charging chart on the machine, nor is there an installation or owner's manual to be found.

  7. #7
    Join Date
    Dec 2011
    Location
    Jacksonville, NC
    Posts
    6
    and i'm not really asking for diy advice. I didn't ask or recieve info on how to charge a system, nor did I ask or recieve info on how to perform a diagnoses or how to go about solving the problem. my now main concern is, is it normal for the pressures to be fluctuating during the operation of a package unit heat pump? (which I am coming to the conclusion the answer is yes), and is it normal that the low operating pressure is only 20 degrees (50-60 psi) with the outdoor temp of 55 and indoor set temp to 70?

  8. #8
    Join Date
    May 2002
    Location
    Houston Texas
    Posts
    6,315
    Quote Originally Posted by Impulse View Post
    and i'm not really asking for diy advice. I didn't ask or recieve info on how to charge a system, nor did I ask or recieve info on how to perform a diagnoses or how to go about solving the problem. my now main concern is, is it normal for the pressures to be fluctuating during the operation of a package unit heat pump? (which I am coming to the conclusion the answer is yes), and is it normal that the low operating pressure is only 20 degrees (50-60 psi) with the outdoor temp of 55 and indoor set temp to 70?
    Son you need to read the site rules, if you cannot perform and understand this simple task good luck.

    Next if you are in the HVAC profession, get your post count up to fifteen and apply for pro status. Once you become a PRO we can give you all the help and knowledge you can handle in the PRO forums.

    In the meantime have a PRO come look at the system, if you work for a company ask a seasoned tech come out and ask to assist so you can learn.

  9. #9
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,073
    Quote Originally Posted by Impulse View Post
    ok i'll re-state my previous post. I am an apprentice hvac technician of 2 years, and I would like help on diagnosing the problem of this system. It wasn't heating the house earlier, and I charged the system with MY guages, and MY r22 freon that I bought because I have have my cfc certs. I just have not had much interaction with heat pumps, and am finding this confusing as to why there is no steady pressure, and why the suction pressure is so low compared to the design specs. also, can it even be diagnosed properly without sc or sh being calculated
    step away from the refrigerant grasshopper...call a sr tech in your company
    for a lil help..or get your post count up where we can help you in the pro side

  10. #10
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I don't see how a short cycle is a problem here. That means it's putting out plenty of heat. If it's only 55F, which depending on where you live, the unit shuld be running about 1/3 of the time. If anything it might indicate the unit is oversized.

    Do you have a thermometer? Can you measure static pressure? If yes and yes, then you can calculate the totl BTU's based on temperature rise and airflow. Take CFM x Temp rise x 1.08. Does the numer seem about right for that model given hte outside tmepratures? Use the equipment data sheets to determine what the capacity should be at given conditions.

  11. #11
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    Jan 2004
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    Lancaster PA
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    67,597
    Moved to Tech to Tech Forum.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  12. #12
    Join Date
    Dec 2000
    Location
    phoenix, arizona
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    I recommend you have your mentor standing beside you, walk you through step by step, have him explain what's happening as you go through the steps. You will learn a lot.
    Decide what you want, decide what you are willing to exchange for it. Establish your priorities and go to work." H.L. Hunt

    "In order that people may be happy in their work, these three things are needed: They must be fit for it. They must not do too much of it. And they must have a sense of success in it." John uskin

  13. #13
    Join Date
    Dec 2011
    Location
    Jacksonville, NC
    Posts
    6
    thanks everyone for the posts, and for all who commented on me getting up enough posts to get to PRO status, well, that is one of my goals in this line of questioning. I also got the one answer I was looking for earlier that NO, I can not accurately determine the cause of the low pressure without determining the sub cooling and super heat first, which takes me out of the game of any further diagnosis of my system until I aquire a thermometer to attach to the suction and liquid lines. A sr tech at my company has one so I will be using his aid in the near future. Thanks again people! oh and motoguy, I am positive that this 3 ton package unit definitely oversized for the house, but I will be doing air distribution calculations soon.

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