HEADMASTER

[esw]

I BELIEVE I MAY HAVE A POSSIBLE HEADMASTER PROBLEM BUT BEFORE I JUMP TO ANY CONCLUSION WITH THE INFORMATION PROVIDED DOES ANY ONE HAVE ANY FEED BACK OR SUGGESTIONS.DON'T HAVE THE SPECIFICS AT HAND RIGHT NOW AS FAR AS PRESSURE READINGS AND TEMP READINGS HAS ANY ONE DEALT WITH AN ISSUE AND THE HEADMASTER WAS THE PROBLEM AND IF SO WHAT WERE THE SIGN'S TO LOOK FOR,OR WHAT DID YOU DO TO COME TO THAT CONCLUSION.I'M not to familiar with the actual purpose and function of headmaster in the system if u can,and have time can u give a brief run down on what it's purpose serves.SYSTEM NOT COOLING WALIK-IN BEVERAGE COOLER EVAPORATER FANS RUNNING ,COMPRESSOR RUNNIG,HIGH HEADPRESSURE DNT REMEMBER SUCTION PRESSURE READING BELIEVE IT WAS AVERAGE OR ABOVE AVERAGE CONDENSER COILS SMASHED.THANKS GO EASY ON ME!.:)

[John Markl]

I BELIEVE I MAY HAVE A POSSIBLE HEADMASTER PROBLEM BUT BEFORE I JUMP TO ANY CONCLUSION WITH THE INFORMATION PROVIDED DOES ANY ONE HAVE ANY FEED BACK OR SUGGESTIONS.DON'T HAVE THE SPECIFICS AT HAND RIGHT NOW AS FAR AS PRESSURE READINGS AND TEMP READINGS HAS ANY ONE DEALT WITH AN ISSUE AND THE HEADMASTER WAS THE PROBLEM AND IF SO WHAT WERE THE SIGN'S TO LOOK FOR,OR WHAT DID YOU DO TO COME TO THAT CONCLUSION.I'M not to familiar with the actual purpose and function of headmaster in the system if u can,and have time can u give a brief run down on what it's purpose serves.SYSTEM NOT COOLING WALIK-IN BEVERAGE COOLER EVAPORATER FANS RUNNING ,COMPRESSOR RUNNIG,HIGH HEADPRESSURE DNT REMEMBER SUCTION PRESSURE READING BELIEVE IT WAS AVERAGE OR ABOVE AVERAGE CONDENSER COILS SMASHED.THANKS GO EASY ON ME!.:)

A headmaster backs liquid up into the condenser in order to "make it effectively smaller" to force head pressures up during cold outdoor weather. It also bypasses hot gas directly to the receiver from the compressor to raise the head pressure.

A simple test would be to feel the liquid line before and after the headmaster. If the liquid line AFTER the valve is warmer than the liquid line coming from the condenser, it is bypassing.

They tend to fail in "full bypass"......When this happens, the outlet liquid line will be the same temperature as the hot gas line feeding the valve, because there is no condensing taking place.

On larger systems (supermarket racks), when this would happen, we would break the cap tube stem off the diaphragm so it would release until we could return with a new valve. Yes, this technically created a system leak, but when the milk is going sour and the biscuit tins are popping, you gotta do what you gotta do.....

[madblack]

only headmaster problem I encountered was low charge. it showed as high heat pressure , but badly flashing sight glass. most of the liquid was backed up to the condenser and the receiver was running dry, as I recall the liquid line was quite hot which looking back i suppose was from discharge gas going staightt thru the reciever. added 5# and everything went back to normal.

[John Markl]

only headmaster problem I encountered was low charge. it showed as high heat pressure , but badly flashing sight glass. most of the liquid was backed up to the condenser and the receiver was running dry, as I recall the liquid line was quite hot which looking back i suppose was from discharge gas going staightt thru the reciever. added 5# and everything went back to normal.

Yep, you get it to "push over"....and once it does, the reciever level generally jumps way up....:cheers:

[madblack]

I never did what I would call a lot of commercial Refrige , but that one was a puzzler , I wish I could say I figured that one out myself , but I had to call one of the company smartguys to get some insight to the LAC valve too. was freezing my heuvos off on a nite call! and over my head

[John Markl]

I never did what I would call a lot of commercial Refrige , but that one was a puzzler , I wish I could say I figured that one out myself , but I had to call one of the company smartguys to get some insight to the LAC valve too. was freezing my heuvos off on a nite call! and over my head

You get used to it.....The first cold snap, your medium temp racks show "empty" receiver, and headmaster in full bypass.....Usually a 30-pounder in the rack (that held 7-900) would shove it over, and "poof", your receiver is at 30 percent again....

[madblack]

question , John the bulb , isn't that charged with nitrogen ?, cuz I seem to remember someone else said you could bust off the tube in a pinch and he had said that it wouldn't leak refrigerant for that reason.

[jpsmith1cm]

http://www.sporlanonline.com/90-198.htm

http://www.sporlanonline.com/90-30.htm

http://www.sporlanonline.com/90-30-1.htm


For the newbies, please read them in order.

It explains the reasons for head pressure control, the mechanisms of head pressure control and the proper way to charge a unit with these head pressure control mechanisms.

[akelesis]

i came across where at a ice machine.. the head pressure was not high enough which would cause the harvest not to make ice fall and cause the evap to get filled with ice and would cause it to go off on safeties the strangest thing when i called up scotsman they said that there was a recall on all scotsman a few yrs back that this headmaster control needed to be upgraded. but they didnt warrenty the part.. which cost me extra and the customer wasnt happy.. )-: