Retired engineer has pressure problem!!!!!!!

[chiller man]

Hello again every one, Chiller man here! \have not been on for some time but, if you have read my blogs from last year you will understand that I retired from refrig in the 90s, after 30 great years in the game. I got my lad involved with an apprenticeship leaving school and is doing well. Passing city & gilds last year, but still very wet behind the ears, you cant beat Exp. Perhaps Im the num nut,but I am confused, he keep telling me that AC systems now run at certain pressures, depending on the gas used. If the suction and head pressures are a certain pressure,things must be ok. He says there are no site glasses any more, so how can you tell the condition of the liquid! What happened to the good old walk round, feeling pipe temps, listening and looking.Is this the case now?and why.can somebody explain this to me.Thanks all.

[Paul J]

This is typical of new refrigeration technology, the manufacturer has done all the R and D and knows how much refrigerant the unit requires to run correctly, On the side of most fridges and aircon units it states the weight of refrigerant required, new guys to the trade just repair the leak, evac and then weigh in the correct charge, this is usefull but I do believe it dumbs down the engineer

[chiller man]

Thanks for that Paul and I agree with your final comment! God help em if they have to find a problem. ooOO Dear!! all the best mate.

[momo]

Most of the gear our there is very carefully engineered to carry the correct charge for operation sometimes within very small margins of 10s of gramms (or 1/4 ounces!!). BUT what do you do with all the refrigerant you take out ? Send if to be recycled, fill it back in...? (Evidently not in the case of a serious loss.) Can you accurately weigh in under windy conditions on a roof/ladder with the bottle bobbling around - so you should know how to get it right. And can you distinguish a real refrigerant system fault from the electronics and weird (intelligent? /fuzzy logic !!!???) programming of the unit giving you fake errors or a sensor a bit off Temp/Resistance curve or an unexpected occurence like e.g. rain causing the condenser to overcondense suddenly and trip a fault elsewhere...? Feeling temperature and vibrations, listening, smelling and using your eyes and grey matter are still valuable tools.