Questions I am afraid to ask my boss and co-workers

[cmclifton]

Never seen a sight glass on a unit with 10 degrees of subcooling...

If it has a sight glass and a TEV and bubbles its wrong.

How about one of those units that has a TEV and a sight glass but no receiver, or something like half of the units that have R507 in them?

[SBKold]

Ryan - well yes .....did you mean ever see a unit with 10SC and bubbles?

[jpsmith1cm]

I think I misspoke and unfairly painted my boss as a jerk...I should have said I am too embarrassed to ask some questions. I usually try to find my own answers either here or from a book. I'm a new guy, but I'm older and get self conscious when I don't know something or can't find the answer or figure it out on my own.

That being said...how I usually charge a system. I don't go by pressure. I try to think temperature. I weigh in the charge when I know that information. Then I look at condenser split and TD. Then I make sure there is some subcooling if it has a receiver and a TEV and I make sure the superheat is okay. I heat the receiver and make sure it is a quarter to a half full unless it has head pressure control, then I like to go a little more. If everything is reasonable and the glass is still bubbling I call someone and ask what the hell I should do now.

If you've got a head pressure control (I'm assuming here that you mean a headmaster valve) there is a specific procedure that one can follow to ensure proper charge.

http://www.parker.com/literature/Spo...90/90-30-1.pdf

It might seem a bit confusing, but it isn't really that tough to do.

Have any of you guys ever seen a full sight glasses with 10 degrees subcooling?

Not often, but I have.

[ClimateCntlJohn]

Don't ever listen to anyone who says "I usually charge to x pressure "

If you can get used to looking at sat temp instead of pressure you will be on the right track. Because pressure is relative to the design unit you are working on.

I would tend to think you had measurement error with 15 deg sc and bubbles.

Yes rla and Fla are same thing and anytime its close I'm looking into why. Usually a 208/240 unit will show Fla at 208.

As far as high side guage connection if you were measuring the hot gas line you will not be accounting for pressure drop through condenser coil. The pressure at the reciever will be slightly less. This may lead to innacurate subcooling calculation. Maybe why you thought you had 15deg.

Go to efficientcomfort.net and check out waynes brain analyzer. Learned a ton from that very useful tool.

Neat site bro, thanks for the link.

[air1]

I would suspect non-condensables or a pressure drop across the LLFD.

[ryan1088]

Ryan - well yes .....did you mean ever see a unit with 10SC and bubbles?

Lol durrr. I have to quit posting during lunch while people are talking to me....

[MikeySq]

delete

[tuba]

I made a cross country move and joined a large company. After many months probation pay and no raise and only working on rooftops, I moved to a small refrigeration company that really needed help. The price and benefits were right, so I signed on. I explained to them that I might be a little rusty from working on rooftops for a year, but I would get back to speed pretty quick. They said that would be okay. I gave notice to the big company and they fired me on the spot (standard policy) and started with the Refrigeration company. One day on the job I asked the service manager about what was the ideal temperature for an ice cream freezer (I really forgot). Exactly one week later I was fired and told that "we are not paying you a training wage". At least my co-workers told me that the manager was a little nuts and that I was the SEVENTH technician that he had done that to in the last two months.
Moral of the story is: Keep some phone numbers of technicians outside your company who you can talk to and ***** to and ask questions to. It makes the job much easier knowing you have someone to call in a pinch. The good thing is, thanks to that guy firing me, I found the best company, benefits, and wages that I have ever worked for.

[2sac]

Since the RLA/FLA thing has been cleared up ill weigh in on the charge thing. If it has a sight glass and a TEV and bubbles its wrong. The TEV must have a full column of liquid to do its job correctly. If it does not it will hunt continuously. Some subcooling does not = a full charge. With a TEV a full column of liquid feeding that TEV under all ambient conditions= full charge. On the system you have I'd say fill the glass first then take readings. Cannot adjust TEV to set superheat without full column of liquid. Gotta be checking liquid pressure to know what your subcooling is. You can check discharge super heat with discharge pressure.

There is one exception to this rule that I know of. 414b See #4 and #5 under system charging http://www.icorinternational.com/images/hsss.pdf

[rselby]

You can't correctly sub cool with a mixture of liquid and vapor, you must have a solid column of liquid all the way to the TXV.
Gas it up and let it shut down while you monitor system pressures, SH, SC, amp draw. Adjust from there if necessary.

[toocoolforschool]

I made a cross country move and joined a large company. After many months probation pay and no raise and only working on rooftops, I moved to a small refrigeration company that really needed help. The price and benefits were right, so I signed on. I explained to them that I might be a little rusty from working on rooftops for a year, but I would get back to speed pretty quick. They said that would be okay. I gave notice to the big company and they fired me on the spot (standard policy) and started with the Refrigeration company. One day on the job I asked the service manager about what was the ideal temperature for an ice cream freezer (I really forgot). Exactly one week later I was fired and told that "we are not paying you a training wage". At least my co-workers told me that the manager was a little nuts and that I was the SEVENTH technician that he had done that to in the last two months.
Moral of the story is: Keep some phone numbers of technicians outside your company who you can talk to and ***** to and ask questions to. It makes the job much easier knowing you have someone to call in a pinch. The good thing is, thanks to that guy firing me, I found the best company, benefits, and wages that I have ever worked for.

I'm willing to bet there is more to this story. On the other hand I have worked with some pretty prickly folks, especially the ones who are bosses sons.

[icemeister]

There is one exception to this rule that I know of. 414b See #4 and #5 under system charging http://www.icorinternational.com/images/hsss.pdf

That pdf file won't open for me.

Can you summarize what they said about charging with R414b in #4 & #5? Is it about the danger of overcharging if you clear the sightglass?

[2sac]

That pdf file won't open for me.

Can you summarize what they said about charging with R414b in #4 & #5? Is it about the danger of overcharging if you clear the sightglass?

System charging
1. Initially charge 80% of R-12, 90% R-134a
and 100% of R-500. Do Not exceed
115% of OEM charge
2. Remove liquid only from cylinder
3. Charge refrigerant in the receiver or
high side of the system with the
compressor off.
4. Run system and add refrigerant if
needed to design subcooling. Adjust
TEV if needed. Never charge system by
clearing sight glass
5. For Fixed Metering Device Systems.
Charge by compressor superheat