Page 1 of 6 123456 LastLast
Results 1 to 13 of 75
  1. #1
    Join Date
    Dec 2009
    Location
    Ontario , Canada .
    Posts
    95

    RTHD , oil return issues .

    I have an RTHD under contract , about five years old . Machine has shut down on loss of oil pressure twice . On the initial alarm I added two gallons of oil . Two weeks later another alarm .
    The machine opperates at approximatly 60 to 70 % demand this time of year . Oil pressure drop across the oil filter is approximately 5 psig or less . Oil pressure is approx 119 psig . Oil heaters working . Condensor tubes clean . Leak checked , and charge recently weighed back due to a previous leak . Oil return gas pump is cycling normaly .
    I have recently observed the liquid level sensor fluctuate between 2 and -2 causing the approach to increase and decrease by 3.5 F , the expansion valves appear to be opperating well . If my refrigerant level is not consistant would this not cause poor oil return and thus cause my oil reservoir sensor to go " dry " causing the machine to trip on loss of oil ?. I believe the replacement liquid level sensor is of new design , perhaps for a reason such as this one ? .

    Your thoughts on this would be greatly appreciated .


    CumulusMech

  2. #2
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,081
    So you added two gallons of oil , did you actually check the oil level before you did that to see if it needed it . If it didnt leak out then it didnt need it . Adding oil to an RTHD that is losing oil will make it worse and loose more oil as you will get oil logging in the evap . By adding the oil your problem is going to snowball .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  3. #3
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,081
    Another thought , you say the gas pump is working . How do you know ? just because the solenoids are alternating does mean its working ,the check valve could be blocked /stuck etc.
    Did you hook up you laptop and run trendview to check "The Heartbeat" this is proof that the gas pump is working .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  4. #4
    Join Date
    Dec 2009
    Location
    Ontario , Canada .
    Posts
    95
    Quote Originally Posted by graham View Post
    So you added two gallons of oil , did you actually check the oil level before you did that to see if it needed it . If it didnt leak out then it didnt need it . Adding oil to an RTHD that is losing oil will make it worse and loose more oil as you will get oil logging in the evap . By adding the oil your problem is going to snowball .
    Hi Graham

    Thank you for your response . At the time of the alarm I was monitouring the oil level sensor . I observed the sensor go dry and then the machine shut down on oil pressure failure . The only solution to that problem was to add oil . Perhaps I added too much , perhaps one gallon or less too much . If that creats oil logging it must be a very sensitive machine . The machine btw is 300 tons . Now that I think of it , when my refrigerant level is at 0 i achieve a 1.5 F approach , which is bang on . If my refrigerant is oil logged I would see a change in approach on the evaporator .
    I geuss I am hung up on the refrigerant level sensor . If the level fluctuates , like a thermostatic expansion valve temperature swing as it hunts , then could there be a problem with oil return ? .


    Peace

  5. #5
    Join Date
    May 2002
    Location
    Long Beach, New York
    Posts
    89
    You might want to check the condenser water temperature as well. RTHD's don't like the ware too cold. Had same problem which raising condenser water temp. corrected. As has been noted in previous threads need bypass and maybe fan control to control water temp.

  6. #6
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,081
    So you added 2gallons of oil and never checked the level ?????????? Big mistake with an RTHD . These machines are critical when it comes to oil / refrigerant charge .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  7. #7
    Join Date
    Dec 2009
    Location
    Ontario , Canada .
    Posts
    95
    Quote Originally Posted by graham View Post
    Another thought , you say the gas pump is working . How do you know ? just because the solenoids are alternating does mean its working ,the check valve could be blocked /stuck etc.
    Did you hook up you laptop and run trendview to check "The Heartbeat" this is proof that the gas pump is working .
    I have TechView , but our company laptop has the the port locked out . Its a subject of great frustration . Once i get the service manager to get off his hands and address this issue I will do this . The only access to info is the IOM off the net , thats it .
    I think its time to buy my own laptop . I just get tired of dropping thousands of after tax dollars to support someone elses company and profit . I geus I have a bad attitude .


    BTW the condensor entering temp is a constant 85 degrees .

  8. #8
    Join Date
    Dec 2009
    Location
    Ontario , Canada .
    Posts
    95
    Quote Originally Posted by graham View Post
    So you added 2gallons of oil and never checked the level ?????????? Big mistake with an RTHD . These machines are critical when it comes to oil / refrigerant charge .
    Please read my second thread . Also could you please explain what you mean by critical oil and refrgerant charge . If I am over or under by a pound or two the machine is going to crap out ? . The charge was just weighed in . How can one gallon of oil logg refrigerant ?. You are beggining to concern me . And if the liquid level sensor is working properly then the oil scimmer can return oil back to the compressor . I must be missing something .
    BTW , I did try to check the oil level . I ran the machine at 40% for 20 min , shut the machine down for thirty . However , I must have had a pessure diferential as the sight glass remained full and I could not achieve a level , and yes I must have passed some oil to the condensor , it could not have been much as the condensor valve was open long enough to check quickly and then isolated . Thats when I had to add the oil . There had to have been one alarm prior to this or I would not have checked . I will verify this in the history .

  9. #9
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,081
    What has the liquid level sensor got to do with oil return ???
    The oil charge is much more critical than the refrigerant charge ,if you weighed it in then you should be ok . But just guessing at the oil level and adding oil without accurately checking the oil level in the sump is asking for trouble . Has someone closed the oil sump vent valve by mistake ??
    Checking the oil level with a standard refrigerant sight glass is a PITA . I have a 10" long glass which gives an accurate reading every time no fooling around up and down with the glass .
    Without techview and the ability to use it properly to troubleshoot all the oil system components your flying by the seat of your pants on this one .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  10. #10
    Join Date
    Mar 2007
    Location
    State of Confusion
    Posts
    1,210
    Quote Originally Posted by CumulusMech View Post
    I have an RTHD under contract , about five years old . Machine has shut down on loss of oil pressure twice . On the initial alarm I added two gallons of oil . Two weeks later another alarm .
    The machine opperates at approximatly 60 to 70 % demand this time of year . Oil pressure drop across the oil filter is approximately 5 psig or less . Oil pressure is approx 119 psig . Oil heaters working . Condensor tubes clean . Leak checked , and charge recently weighed back due to a previous leak . Oil return gas pump is cycling normaly .
    I have recently observed the liquid level sensor fluctuate between 2 and -2 causing the approach to increase and decrease by 3.5 F , the expansion valves appear to be opperating well . If my refrigerant level is not consistant would this not cause poor oil return and thus cause my oil reservoir sensor to go " dry " causing the machine to trip on loss of oil ?. I believe the replacement liquid level sensor is of new design , perhaps for a reason such as this one ? .

    Your thoughts on this would be greatly appreciated .


    CumulusMech
    If you had some contact info in your profile you could receive some more info you could read..

  11. #11
    Join Date
    Dec 2009
    Location
    Ontario , Canada .
    Posts
    95

    Red face

    Sorry , your right , I did not do my homework . Sooo , to heck with this liquid level sensor theory . Well then , I will get the port operational and check the machine out . I will try and examine the check valve as well . I will also look into this sight glass as the one I obtained was the standard 1/2 inch .

  12. #12
    Join Date
    Mar 2007
    Location
    State of Confusion
    Posts
    1,210
    put your email address in your profile. I could send ya some stuff.

  13. #13
    Join Date
    Dec 2009
    Location
    Ontario , Canada .
    Posts
    95
    Quote Originally Posted by maxpower View Post
    put your email address in your profile. I could send ya some stuff.
    .
    My information is up .

Page 1 of 6 123456 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event