Loss of Freon When Checking Subcooling Superheat ??

[GAHomeOwner]

When a technician is testing the charge level or subcooling or superheat, and is using gauges with hoses that are several feet long, how much Freon is lost from filling up the hoses? Should the technician have a canister of Freon with him to replace what is lost when he completes his system check? Thanks.

[lra]

If the hoses have low loss fittings like most of ours do, the loss is minimal and would take several thousand "checks" before affecting performance.

[DPSwitch]

With low loss fittings and proper techniques you won't lose enough to make a difference with regular service. Should they put more in just because they hooked up? No. The amount you are talking about is not readily measurable, so all they would do is screw the charge up.

[beenthere]

Should he have a jug of gas in the truck yes.

Should he try to put .25 oz. back in, no. ( presuming low lose fittings )

[allstar08]

Be careful, many of the techs on this site and many in the field use one set of gauges for all residential refrigerant types. Which means they dump the charges on their gauges after each use. If your system is near critical and the tech has 6 foot hoses it could affect system performance.

[Dad]

Be careful, many of the techs on this site and many in the field use one set of gauges for all residential refrigerant types. Which means they dump the charges on their gauges after each use. If your system is near critical and the tech has 6 foot hoses it could affect system performance.

(cough)

Bull****

Please explain to this group what you mean by "critical charge" on a residential unit and how loosing less than on ounce of refrigerant will matter.

[DPSwitch]

critical charge .....resi AC....... naahhhhhh

besides..... most resi guys do not dump the hose charge between calls, they deal primarily with just a few refrigerants and have a set for each.

[firecontrol]

Be careful, many of the techs on this site and many in the field use one set of gauges for all residential refrigerant types. Which means they dump the charges on their gauges after each use. If your system is near critical and the tech has 6 foot hoses it could affect system performance.

I dump the charge from my hoses after every check. Matter of fact I disconnect from the high side of the equipment first, open the high side of the guage to the crossover and then slowly open the low side of the guage to the crossover. IE: I put what liquid I took out of the system right back in. The only thing thing left in my guage set when im done is whatever gas it'll hold at the pressure of the low side. Anyone ever measured how much that is? Oh........ I run 5' hoses if someone is going to do the measurement.

[toy501]

diminimus

[DPSwitch]

Yeah firecontrol.... I think every good tech does that.... I was just saying that you would not vent the hoses to atmosphere between calls.

[Joe Harper]

I belive that a 6' hose holds 1 oz of liquid refrigerant

[allstar08]

Relax everyone!!!!

I said to be careful. I now all you amazing techs out there, like myself, dump your charge back into the system on the low side. Or I have a set of gauges for 410 and 22 with low loss fittings and valves, the best method IMO.

There are however techs out there who don't and you lose a oz. or 2 every-time they hook up. Over time that adds up, and the last tech to hook up could be the one that drops that charge just enough to make a noticeable difference.

The odds on this happening are small, so I will back down.
I was trying to be technical and I will never do it again.

[BigJon3475]

23 grams (3/4 of oz) is what my scales said I hold in my liquid line thats full. Suction or low pressure side didn't show any difference.

[smokin68]

I dump the charge from my hoses after every check. Matter of fact I disconnect from the high side of the equipment first, open the high side of the guage to the crossover and then slowly open the low side of the guage to the crossover. IE: I put what liquid I took out of the system right back in. The only thing thing left in my guage set when im done is whatever gas it'll hold at the pressure of the low side. Anyone ever measured how much that is? Oh........ I run 5' hoses if someone is going to do the measurement.

I pre-charge my gauge hose set before I hook them up.......




















yeah,yeah, that's the ticket.

Actually I don't.

[BobbyBJr]

Only 1 oz or so, huh? I remember reading somewhere that a 6 ft hose held 5 ounces of liquid and the article warned against using the high side gauge unless you had reason to. Have I been mislead all these years on something else???

[BigJon3475]

I always attach the high side gauge I don't know subcooling otherwise. I will recheck my gauges with the liquid line filled but that was what I got the other day.

[Shophound]

I pre-charge my gauge hose set before I hook them up.......

I've done that for a critical charge ice machine using 404A. Learned by doing that they were DEAD serious about that machine being critical charge!

Wouldn't cross my mind to do it for a resi R22 or 410A system, however. I do isolate the high side and then let the remaining liquid charge in the hose back into the low side. That's just good practice.

[KB Cool]

however. I do isolate the high side and then let the remaining liquid charge in the hose back into the low side. That's just good practice.

Along with the AIR too?

[BigJon3475]

Air is always purged through the gauges upon hookup.

[Mr Bill]

When a technician is testing the charge level or subcooling or superheat, and is using gauges with hoses that are several feet long, how much Freon is lost from filling up the hoses? Should the technician have a canister of Freon with him to replace what is lost when he completes his system check? Thanks.

O God! how to folks get so bored? I wished I had time to worry about stuff like that,
heck with my busy life that would be like meditation to me.