Charge weight?

[lorano]

How accurate are charge weights on fridges/freezers?I would say almost 80% of fridges/freezers that I've had to recharge always need more.

[frank]

Are you talking domestic or commercial?

[1mikeefc1]

I would agree completely, I start to weight in and then have to add more so change the data plate markings. Don't see any point in putting the weight on anymore.

[install monkey]

bear in mind when u weigh in gas- ur gonna have refrigerant in ur hoses- unless u can pump it down to 1 psi.
ur scales are only weighin whats left the bottle-not whats in the system
and unless ur usin kwik couplers or core removal tool or a dedicated gauge point with isolation valve ur gonna lose somme to ozone

[1mikeefc1]

Fair point but you don't lose 100grams taking lines off a cabinet. The amount of our engineers who are weighing it in and leaving is ridiculous, someone only has to go back tomorrow. At least going off pressures and temperatures engineers had to do their job properly.

[install monkey]

depends on the muppets in charge of the gauges!
387310_149602318480094_81509002_n.jpg
this apprentice dropped about 2kg tryin to take gauges off a liquid line

[chilliwilly]

When I worked at Lec, the units were bomb charged up to about 80-90% of their designed charge from a predetermined dose, left to run for about 1/2 hour for the gas to cycle and settle, and then topped off until the suction line started to sweat. Some of the units needed less, and some needed more than their designed charge, due to the slight variations in the compressor performance. Some of the more modern commissioning lines had meters on the charge rigs, and the others had a scale on the hoists that lifted them off the lines, and every so many, the weights were compared before and after charging. And every 100th unit were run for 24 hours for quality control.

I think with new equipment that's made in countries that deprive the Western population out of jobs, if they bother to pull a full vacuum, they probably pull it too fast, or don't pull down far enough. Leaving non condensables giving immediate problems, or sometimes only noticeable in warm weather. Then bomb charge the recommended dosage without allowing it to settle to see if it needs a top off.

With regards to critically charging on site, the same procedure needs to be adopted with bomb charging up to 90%, then topping off after allowing the system to settle. Instead of trying to get the prescribed amount in there as quick as possible without allowing to settle, and then going. And then having to go back to do that another day.