HVAC Questions? Ask an HVAC Expert for Answers ASAP
By the readings you've gotten, it sounds like the system is chugging along as designed. is it having an issue that needs to be addressed? or were you just checking to be sure it's within parameters? as a general rule, you'll want a low-temp (freezer) evaporator to run about a -15 degree saturation (coil) temp. the -16 you have is right in line with that. the condensing pressure will usually correspond to a temperature 20-30 degrees above ambient (condenser inlet) air. you are on the money there. your evap inlet air should be closer to 0. that's the box temp we shoot for in low temp applications. are you checking it with the door open or closed? and, is the unit cycling as normal, or runing constantly? I won't get too far ahead of things here. let me know if there's a problem that needs addressed. if not, have a great day.
there is some question as to the original cap tube size. If the original was .049X10' each and was replaced with .059X12' each, what would be the difference in temperature range. the original cap tube was replaced with the.059. would it be necessary to change or modify the cap tube based on the above readings?
The cold control replacement is a -25 degree control in lieu of a -10 degree control but this should not be a problem except to adjust the control to prevent constant running. am I correct?
A recheck of temp and pressures this morning after 20 hours of running I have 5 buckets of ice inside.
current readings on box:
Box temp: 03 to 05 degrees
Condenser air in: 80 degrees
High side gage: 230 PSI/100 degrees
Low side gage: 14PSI/-22 degrees
If the original cap tube was .049 X 10' (2 pieces) and was replaced with .052 with a length of 12" (2 pieces), would error in length make the difference? By the chart I just found, it looks like the .059 cap is too long. Reading the Supco chart it looks like 79" would have right. Am I correct?
Will the unit function O.K. except that the box temp doesn't get to 0 degrees. can I shorten the tube at next service in about 6 months.
final point. the compressor is new.
Thank you Phil, based on the data provided I think I will leave the system alone for now since it is running close to zero.
Just got back in to check on you, I apologize sincerely for my apparent disappearance. I've been working through some technical difficulties here in my office. I see you've been taken care of by a very experienced and well-versed associate. Thank you Phil.
based on the info provided by you and Phil, I am thinking that I should leave the system as is for know. do I have any problem with doing this? when I service it in the future I may shorten each cap tube to 79" from the current 120". if I am correct the correct length should be 79". do you agree?
The proof of the pudding is in the eating. and this thing is making great pudding right now. I know how nerves can be shaky when you stray from the literature, but in this business, the literature never covers all bases. the literature provides you a reference, this reference assumes exact design parameters are in effect.... which is almost NEVER the case. the extra length of the tube has apparently either not had any effect, or, has offset some other design hiccup that was stealing capacity from the system. either way you're getting results. If you had liquid flooding back to the compressor, or the head pressure running high, you would run the risk of compressor valve &/or seal damage, and my advice would be different. but as is, there's no indication of adverse operating conditions, so if it were me, I'd zip the unit up and walk away. Try not to stew on it too much. like I said the literature assumes perfectly accurate design parameters. If you take the literature as law in all situations, you will be pulling out copious amounts of hair on a semi-regular basis. Thanks again for affording us the chance to help out.