Factory Charge Weigh-In

[HVACGBH]

I would have been starting my career today (rained out) handling new units with a factory charge. We are installing 50 Goodman units at an apartment complex. My assignment was supposed to be handling the charging of the units. My foreman was going to go over some stuff with me before setting me out on this task, but since I am off today I figured I would ask here to see if there is any tips you guys can give me. I know there is a calculation based on line length etc, but not sure if there is anything else I need to watch out for or if its pretty standard charging stuff. Thanks.

[cuchulain]

the install manuals usually have the charging formula if the line length is long.

[SBKold]

What kind of indoor units did you use? That will be a consideration. Also was the correct piston installed in the indoor? As well as lineset size used

Goodman says that charge is good for 15ft only - in my experience it is good to more like 25-30?

If outdoor units have smartcoil 5mm coil the charge is sensitive.

Also manuals have recommendations to upgrade several parts if lines are over 75ft.

[BaldLoonie]

Personally I don't trust that the factory got the initial charge right. I would prefer to check it using superheat or subcool (depends upon meter) on a warm day.

[markvilleman]

If you got a fix bore inside,check the super heat when it's at temp,if u got txv inside,check the sub cooling.

[superdale]

Personally I don't trust that the factory got the initial charge right. I would prefer to check it using superheat or subcool (depends upon meter) on a warm day.

Spot on. Everyone should assume the factory charge is not right. It makes you a better tech, and you will understand more by going through this process.

Gauges, clamp probe, length on lines, coil size, line set size, piston size, air flow testing should all be a part of a basic check for you on all these units. This is a perfect time to really understand how to service an A/C unit. Do it right and you'll thank yourself :).

Dale

[Mille Racer 69]

And if all 50 are Goodman's, 5-10 of them will have to be replaced after you find a leak.

[ARTICHILL]

I agree SH & SC is key ive charge plenty of units using factory weight but my opioin it just gets you there once your there its time to fine tune that sucka

[ironpit]

sh & sc are key, but what happens when the duct work is way off. I have replaced units with supply and return plenums so big I could crawl inside them on a 4 ton unit. The duct board had huge water drops all down the supply. Customer doesn't want the duct replaced, just the equipment. I know guys that figure their returns anywhere from .1 to over .05. Its' hard to get things right when the duct is all wrong.

[Kevin Weaver]

my 1st thought was "are you refrigerant certified"