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Head pressure

Techman
Techman Member Posts: 2,144
edited February 2015 in A-C, Heat Pumps & Refrigeration
Lets see here,it is around 0*F here in L.I.N.Y. and I'm headed out the door to work on an OUTDOOR R22 cond unit,medium temp case.Sitting here in my office, I'm going to take a S.W.A.G. at what the head pressure will be . So, what do u all think it SHOULD be? Come on now, be honest! I've told all of my workers that "I don't know" is an honest answer.I say "I don't know" many times a day, everyday.

Comments

  • pecmsg
    pecmsg Member Posts: 4,843
    Headmaster?
    Fan Cycle?
    Pump Down?
    Low Ambient controls?
  • Techman
    Techman Member Posts: 2,144
    All of the above.
  • Matt_67
    Matt_67 Member Posts: 286
    edited February 2015
    Should be 180 psi. Assuming the low pressure control settings are set to start the compressor at that cold of a temperature.
  • Empire_2
    Empire_2 Member Posts: 2,343
    All depends on how the head master is responding to the "0" temps. What really sucks is if the condenser is in a hi wind area, which will lo ball your head pressure head master or not. Considering perfect conditions,.....200 or so would make me happy.


    MPT...
  • Techman
    Techman Member Posts: 2,144
    95* condensing temp on a 70* day and 125* condensing temp on a 95* day. Most head masters are factory set for 90-95*( + or minus a little) cond temp. Some r404a cond units had an improperly factory installed head master that maintained a minimum pressuse of 180psig which is = to 82* cond temp and that produced an improperly operating TXV. By chance the TXV also requirers a minimum pressure in inorder to atomize the freon properly. The nitrogen charge in the head master will not be affected by any windy cold 0* day.
  • Techman
    Techman Member Posts: 2,144
    Oh my! I do care ,because I work on the equipment as do lots of REFRIGERATION guys. R u a boiler guy?Who cares what the water feed valve press is or the temp of the water going into a radiant system.
  • JUGHNE
    JUGHNE Member Posts: 11,060
    edited February 2015
    Talking Heat pumps??.......with head master and R404A !! LOL

    You would be right about your feeling.
  • njtommy
    njtommy Member Posts: 1,105
    edited February 2015
    You still want a 180- 200psig head no matter what temp is it out side.
    If you don't have a high enough head pressure the TXV will never work right and it will not create enough pressure drop. I prefer head masters over fan cycling.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    Techman said:

    Oh my! I do care ,because I work on the equipment as do lots of REFRIGERATION guys. R u a boiler guy?Who cares what the water feed valve press is or the temp of the water going into a radiant system.

    Techman, I'd ignore what sludge says. I've watched/read a few of his replies on the forum, and it seems he's almost purposely trying to rile people up. Account was registered couple of days ago... Not sure what he's trying to do.
  • Matt_67
    Matt_67 Member Posts: 286
    If you have a balanced port txv and properly sized liquid line you can get by with the lower head pressure but it's all got to be set up right. Liebert has a one piece valve for r22 that has a set point of 225 psi but most of the one piece oroa style valves come preset for 180. If we know that will be a problem we remove them and put on a ORI/ORD setup and then you get whatever you need.

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