charging 410a split on a cold day

[UAPHILLY420]

Any ideas on how to properly charge a 3 ton 13 seer york straight air unit on a brisk day? The unit is equipped with a piston, yes a piston. They recommended charging by superheat but the ambientt o/a temp was too low to intersect the chart on the outdoor panel. I had to get it running so i drove the head up until i got about 16 deg. S.h. I wasnt real happy leaving it that way. Any suggestions?

[GOVHVAC]

weigh it in

[Thomasg]

Ball park is about all you can do until you have a load. Sucks but you should recheck on a warmer day. But In the real world that's about all you can do imo.

[Thomasg]

Weigh it on package and splits check how much condenser charge per ft.

[talktowags]

How long is the line set and what size ??

[UAPHILLY420]

15 ft lineset approx. not including i.d. coil.

[UAPHILLY420]

3/8 -3/4 3 ton. Came with 15 ft of charge. Just wasnt satisfied due to low ambient & low load.

[stickinit2thman]

seeb my thread,charging heatpump in heat mode.

[CELSIUS]

I would do it right. You don't want to risk HO running an overcharged unit. Why piston?

[UAPHILLY420]

Thats what the engineer called for. I questioned the piston too but they didnt care. The condensor was feeding a fcu. It was in an industrial setting.

[BaldLoonie]

York uses a piston. Only trouble with weighing in is you have to ASS-U-ME that the factory got the original charge right which I never believe. Get it close and check it again in warm weather. Got some kind of low ambient control on it? Crankcase heater? 3 ton is probably a recip.

[CELSIUS]

Oh right. I know what you mean. Engineers don't like to be questioned by us, who actually do the work and have a deep understanding of how things work. LOL

[UAPHILLY420]

Scroll compressor, low ambient, & crankcase r. all on it. I guess i will bug the foreman fitter to allow me to go back when its warmer (if there sre any warm days left) N.E.Pa. thanks forr everyone 's input.