installers overcharging txv systems

[Tinner67901]

Here's what I have been finding. I keep getting sent back on our installers new installs. When I get there I keep finding overcharged units. Its usually 90 inside and 90-100 outside when they are setting these units. They say they are charging them to 10 degrees subcooling. When I go back the indoor temp is usually 70-80 depending on the person. The outdoor temp is still 90-100. My subcooling is extremely high around 40-50 degrees. I always remove refrigerant to reach 10 degrees subcooling. What is going on here and how can I help them stop overcharging these units?

[drew2128]

I usually charge the subcool to a lower amount, but I think the best way is to get the wet bulb and go from there.

[Toddbrewster]

Are they adding refrigerant to the system on new installs? Most units come precharged for 15' of line set, I usually do not have to add any refrigerant to my new installs, one this week had a good 35' of line set, R410a, txv metering device and there was a great plenty of refrigerant in the system. Can they start up the a/c and let it run for an hour or so while they pick up their stuff from the job or finish up something inside or what ever so the unit can run for a bit before they go and add any refrigerant??

[GoColts]

Pull the jugs of referigerant off of their trucks. Untill you can show them the proper way to charge a new system.

[pacnw]

charging every unit to the same does not make it correct, unless that is what every unit calls for with conditions!!

[dijit]

First make sure they aren't winging the charging. Worked with a guy that told me that once you are as "experienced as me, you can charge by feel" Make sure they are not doing that.

make sure the unit has been running for a while, and they add refrigerant slowly then wait. There is usually quite a bit of lag for them to "catch up" add some refrigerant and wait 5-10 minutes for the unit to stabilize at the new subcooling.

read manufacturer data on charging that should be included in the service manual with the unit. I know, I know, everyone thinks they know more than the engineers that built the thing, but there is some useful info in there. They will probably have parameters printed based on outdoor temp, indoor temp, etc. If your parameters are outside of theirs, all you can really do is wait to pull down temp, guess, or come back after lunch to top off. Otherwise they will probably tell you how much to add per x number of increased line set as has already been stated.

[beenthere]

When the indoor temp is 90 and your at 100 outside, the TXV will be wide open. And you won't have 10°SC on most systems. Too much load.

Have them measure the line set, and then add as per the manufacturers instructions.

[hvacvegas]

When the indoor temp is 90 and your at 100 outside, the TXV will be wide open. And you won't have 10°SC on most systems. Too much load.

Have them measure the line set, and then add as per the manufacturers instructions.

and if it's an overcharged (from the factory) goodman?

[beenthere]

and if it's an overcharged (from the factory) goodman?

No different then an over charged one from carrier.

[hvacvegas]

No different then an over charged one from carrier.

although I don't install alot of carrier, I don't think I've had one come in overcharged.

With goodman, you never know what you'll get.
It used to be, I'd see 100% overcharged from the factory, and I'd figure on 40' precharge.

Now, I'm seeing some that come in with about 15', some that come shipped with 40'. Maybe I'm getting a mix of new/old stock.

But you know what I mean about charging it.

[truck12]

Have them measure the line set, and then add as per the manufacturers instructions.

Hey, I'm gonna be rich. I'm going to invent a scaled suction line snake so they can work that through the line and get a solid number. Ever accurately measure a lineset in a 12 story condo? (for example).

Point is no one at these places was there when they were built, and no one really knows how to even get an approximate length. In my case I just go behind the installers and readjust the charge, and thats the most accurate it's going to get. We haven't had many problems with this lately though.

[beenthere]

Hey, I'm gonna be rich. I'm going to invent a scaled suction line snake so they can work that through the line and get a solid number. Ever accurately measure a lineset in a 12 story condo? (for example).

Point is no one at these places was there when they were built, and no one really knows how to even get an approximate length. In my case I just go behind the installers and readjust the charge, and thats the most accurate it's going to get. We haven't had many problems with this lately though.

He said new installs. Maybe he meant swap out.

[ironpit]

He said new installs. Maybe he meant swap out.

Be careful Beenthere, that guy sounds like he knows everything. Is it just me or is that irritating?