Code?
Looks like you have superheat, just very low superheat. In fact, I'll bet money that your coil is frozen
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Everytime i go to check SH and all is in the negative numbers, I want to kill myself.
404a system, 4 door reaching freezer...
box temp..+15*, need 0 or less
ambient...100*
head....300psi
suction..25 psi
suck. temp..-2/-8*
discharge temp..165*
I have a PT chart, but need the "code" when in the negative..
thanks..
Let's give nukes a chance.
Code?
Looks like you have superheat, just very low superheat. In fact, I'll bet money that your coil is frozen
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no its not frozen at all, and fans are in order
..where i get lost in the SH is when the temps and psi's are in the negative..
Let's give nukes a chance.
Are you talking Hg?
23 psig for 404a is about -10 degrees F. 27 psig would be about -5 degrees. So consider 25psig to be about -8 degrees. With your temperature readings of -2 to -8, I'd say that you do in fact have some superheat.
I'm willing to bet your gauges are ever so slightly out of calibration, or your thermometers could be. Maybe even both.
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This system was low on refrigerant and the box temp was +22*..I added freon per sight glass and head psi. (headmaster is on system)
box came down to +14.9* and stopped dropping....I took the above readings..
Im using a new digital temperature thermometer.to read the suction line temp about a foot from the compressor..
My gauges may be off but I don't know.....
with the numbers I gave, what is my compressor SH?
Let's give nukes a chance.
-8 minus -2 equals 6 degrees superheat. Ignore the negative sign after you're done subtracting the line temp from the saturation temp.
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thanks shellkamp.
Let's give nukes a chance.
Based on Suva 404a and Du pons app for I phone
-2 6.4 Degrees F
-8 .4 Degrees F
Hope that helps
Im looking for 20+* of compressor SH so I have a ways to go it seems.
thanks all.
Let's give nukes a chance.
I use an SMAN 3. Choose your refrigerant from the list, clamp on the thermocoupler, voila!!! No thinking needed.
Super heat will keep from slugging the pump but super cool will make the ice cream too hard.
Dealing with the subtraction of negative numbers can be quite confusing. I find it helpful to visualize the temperatures using a number line like this:
-12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 < < < < SH = SLT - SST
In your case, with your suction line temperature (SLT) at an average of -5°F and a saturated suction temperature (SST) of -9°F, just count how many spaces (or degrees) there are between -5° and -9°F. I count four space, so your average SH would be 4°F.
If you want to do the math instead, then I use the rule that two negatives cancel each other out to a positive:
SH = -5 - (-9) is the same as SH = -5 + 9, which can be rearranged to be SH = 9 - 5 = 4
The two negatives cancelling each other can be visualized on the number line as well. I think of addition as going to the right, in the positive direction. If you think of the minus sign as telling you to turn around and go in the other direction, you can see that two minus signs would have you going in the positive direction.
Ok, heres what I did..captaincompressor got me thinking I had a superheat gauge, and I did..
hooked it up and I didn't believe my lying eyes...so i hooked up my digital thermometer to the
inlet and outlet on the evaporator...my superheat gauge was correct..6 hours later I have a 0 degree
box...BUT now Im worried about the compressor super heat..Ill go back in the a.m. and recheck it..
this hussmann case is a rebuilt, and Im not impressed..the relays were wrong,, the factory temp gauge doesnt work,
system didn't come with a t-stat or pump down solenoid, one door wouldn't close, (had to replace)..now Im wondering if the txv
is correct for the box and condensing unit...
Thanks for all the replys..icemeister, i will copy your reply and commit it to memory..
Beers are on me....
Let's give nukes a chance.