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TXV bulb install question
Several weeks ago I followed the failed maintenance supers's(several guys) attempts to fix a no cool. I found contaminated R-22 and a TXV installed with the piston still installed. The bulb was also not secured to the piping, nor was it touching anything, just sitting in the air stream. I removed the TXV, pulled a good vacuum and charged the system with new R-22, problem fixed.
Returned to the same property last week, different apartment. This system showed low on Freon, I don't remember the exact numbers but the SH was high and the Subcool was low. It also had a TXV, also not secured to anything just floating around the air stream. I didn't pump down and check for a piston. The pressures did change however when I held the bulb in my hand. I added Freon and left the Subcool at 10. They haven't called back saying it isn't working, but it's created a question in my mind.
These are old Suntherm units, Heat pump. A coil, the bulb jammed between the cover panel and the U bends at the edge of the coil, so not really out in the middle of the air stream.
The question is; Does a TXV bulb always have to be in contact with the piping? What will happen if it isn't? I did notice that when I added R-22, High side would shoot up very quickly, then slowly fall and stabilize.
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The bulb must be attached to the outlet of evaporator and insulated. It response to the amount of super .most are installed at the 10 or 2 o'clock position
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ive always thought i heard 5 and 7 o clock
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When I was in school they said anywhere from 6 to 9 o clock or 3 to 6 o clock
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No oil from refrigerant settles On bottom.Vapor rises therefore 3 ,9,2,or5 gives u best reading.
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I'm sorry 3,9,2,10 o'clock position
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 Originally Posted by hewitt
I'm sorry 3,9,2,10 o'clock position
mmm, cause the powerpoints that I got from when in school say different
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Some books say as long as it's mounted horizontal
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This is becoming interesting.Going to move a bulb around and check some numbers
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 Originally Posted by hewitt
Some books say as long as it's mounted horizontal
Refrigeration Training Services/NATE training slides say Must sense true suction temperature
- not bottom of pipe
- not top of pipe
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So what position does nate say is the correct placement
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 Originally Posted by hewitt
So what position does nate say is the correct placement
from there power points 3 and 9 o clock are the best areas
Last edited by caheiman30; 08-13-2012 at 12:46 AM.
Reason: added picture
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Service valves where u hook up gauges are 3 or9 if u look at them.If these ports were located on top would the boiling are saturation temp be the same on gauges or would it make that much difference
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