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Originally Posted by jrc2905

I was asked to look at a customers walk in beer coolers. There are two identical units side by side. One has a hot shot label on it. The other is unmarked. I told the owner that I could not be sure what refrigerant is in the unmarked unit and asked if he had any idea.
He called the company that has worked on the coolers recently and they said that they did not know what refrigerant was being used but could tell if they gave it a shot of gas.
Now I know a PT chart can help you to decide what refrigerant is in a system and there are some rather pricey refrigerant analyzers but the description of giving it a shot of gas to detect the type of refrigerant is new to me.
Is this slang for some technique that I am unfamiliar with?
I do residential HVAC but recently have started working on small refrigeration units at the request of my residential customers. Any idea on what a shot of gas means?

Reminds me of the early70's when R-12 was$15 a drum. Some clown put up stickers on all pay phones"Tony's service shot of gas $25". LMAO

Thanks for the responses, it is kind of what I thought after I did an Internet search looking at refrigerant identification. I guess shoddy work is not just for residential HVAC.

Originally Posted by icemeister

A shot of gas is an old refrigeration man's term for topping off a system that's a little low on charge, that's all. There's no secret method of ID'ing what refrigerant is in an unmarked system so the only way to do it right is either pay to have it properly analyzed or replace what's in there.

If I were on this call with this new customer, I would first verify that the system was originally designed for R12 and then give a quote to the customer to replace the unidentified refrigerant and the Hot Shot with R401A (MP39) as that is what I stock on the truck and has been my preferred R12 replacement for nearly 15 years.

When in doubt, pull it out.

exactamundo!



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Originally Posted by jrc2905

....Is this slang for some technique that I am unfamiliar with?.... Any idea on what a shot of gas means?

A shot of gas is an old refrigeration man's term for topping off a system that's a little low on charge, that's all. There's no secret method of ID'ing what refrigerant is in an unmarked system so the only way to do it right is either pay to have it properly analyzed or replace what's in there.

If I were on this call with this new customer, I would first verify that the system was originally designed for R12 and then give a quote to the customer to replace the unidentified refrigerant and the Hot Shot with R401A (MP39) as that is what I stock on the truck and has been my preferred R12 replacement for nearly 15 years.

When in doubt, pull it out.

They didn't know what refrig. was in system so they gas it up with r414b ( hot shot)

Look for a tag on condensing unit that my tell what refrigerant it started with. IF not then check powerhead on txv. If nothing there check the setpoints of your hi, low, and fan cycle controls along with a PT chart and you can tell whether it started with 12, 22, or whatever. If it is older most likely 12. There is no telling what replacement they used, you may have to start over from scratch. If its low, a leak repair, new driers, and a micron gauge evacuation to 500.

Never heard of that method. I use my PT Chart. Also, a guy can eye-ball the Powerhead to get an idea of what it started life with.

A shot of gas?

I was asked to look at a customers walk in beer coolers. There are two identical units side by side. One has a hot shot label on it. The other is unmarked. I told the owner that I could not be sure what refrigerant is in the unmarked unit and asked if he had any idea.
He called the company that has worked on the coolers recently and they said that they did not know what refrigerant was being used but could tell if they gave it a shot of gas.
Now I know a PT chart can help you to decide what refrigerant is in a system and there are some rather pricey refrigerant analyzers but the description of giving it a shot of gas to detect the type of refrigerant is new to me.
Is this slang for some technique that I am unfamiliar with?
I do residential HVAC but recently have started working on small refrigeration units at the request of my residential customers. Any idea on what a shot of gas means?