Beer can cold
How did or why did this get bandied around as a "tip"?
At some point way back in the day, was that the acceptable measure, along with a 30 degree rise in temp of the air through the OD coil (which was another "tip" I have heard several times)?
When I was going through the schooling portion of my apprenticeship, the teacher actually told us this was a acceptable tool for a rough rule of thumb as to how the system was working,,, I believe the statement went like this;
suction line beer can cold.
Then they invented digital gauges like the 550......love it.
Never give up; Never surrender!
All i can say is if a doctor took my temperature and said I was "patty melt warm" i'd be questioning his credentials
Originally Posted by k-fridge
Nobody is saying it is right. Asking how it came to be such a common "tip" all over the country.
Originally Posted by SoFlaDave
I was explained the beer can cold one by a good teacher at UTI, but he said it was a benchmark for PM and not to charge or diagnose by this method.
IDK how it came about but I have seen some of the older units that ran that way 20 plus years...
I wonder ,as an experiment what would happen if you used these methods to charge a sys.,not necessarily30 over amb...but say twenty and 16 to 18 across the coil....then checked against the traditional method....how close would it be?
Beer Can Cold No Good?
How about Super Cold Beer Can Cold?
If You Can Dodge A Wrench You Can Dodge A Ball
Same goes for a sight glass in the liquid line on a 410A system and charging til it's full, it will be overcharged from what I've been told because it's flashing before it gets to the txv so the guy just kept filling it up.
Originally Posted by sprmktrefertech
A suction line is beer can cold? Whoever started this goofy "tip" must have liked warm beer.
Or he was from Germany
Originally Posted by Lurch77
Do you guys remember the old Carrier unit w/ the suction accumulator ,the one that always leaked because of the copper plated steel inlet and outlet....I guess they new it was a problem...and well...tried to correct it w/ an accumulator. talk about flood back.
If you go back to those days residential A/C was new. And most were add on's to existing gas/oil furnaces with blowers built to move hot air only.
Whole house A/C was new and things were simple. Simple to the point that a lot of those systems lasted 15, 20 years plus as compared to todays Hi Tech systems.
So we had to work with what we had which typically meant adding a cooling coil on top of a furnace and doing something to the blower to increase the speed to handle the heavier cold air.
And there were always expansion valves and liquid line sight glasses in all systems. The factory SH setting out of the factory was typically 12 degrees and that was and still is for the mechanical refrigeration effect advantage to provide the proper temperature of the discharge air from the cooling coil so the house would cool to design temperatures.
We never measured or had to worry about setting the system up at 12 degrees SH at the suction port of the condensing unit simply because that is not what a 12 degree setting is meant to be used for.
If we measured the SH we measured at the outlet of the evaporator for set up or trouble shooting.
So, in order for us to set a system up in an era when everything was new we analyzed the systems from top to bottom which led us into developing certain rules of health for what a properly operating add-on whole house air conditioned looked like.
Some of what we leared was to look for a 20 to 25 degree Delta T between the inlet/outlet of the evaporator. Another was a full sight glass after the system stabilized, which typically meant letting it run for 10 to 20 minutes if the house was getting close to thermostat set point. Another was the temperature of the suction line which we would grab & hold for two reasons; to see if it was getting cold --and that, in a hot and humid climate, would cause the suction line to sweat but maily, we could feel if any liquid was flooding back to the compressor.
And the final checks included compressor amp draw compared to factory specs and a Delta T of about 30 degrees between the inlet/outlet of the condensor.
That is what we were looking for.
Also, the term beer can cold came about because of the invention of aluminum cans during the same time period. Pull a cold aluminum can out of the cooler and let it set outside and it would sweat, condensate much more than a glass bottle of beer.
So those two things happened together hence the term.
All those things served us well. Well enought to install systems on the fly that lasted many, many years unlike a lot of the systems of today.
The measurement of SH at the compressor was actually started and, in some case, required by the compressor manufacturers in the 80's due to so many compressor returns for warranty where the compressors checked out fine or the cause of failure was liquid slugging, which was evident when the compressor was cut apart.
So the compressor manufactures started demanding that the set-up technician record the SH at the condensing unit in order to protect their financial interest. And that policy has stuck in this industry since with the new definition that setting the superheat to 12 degrees when the new unit/old unit is first started/repaired is the proper thing to do and evident of a properly operating system.
Super heat is to be measured at the outlet of the evaporator and not at the condensing unit. All the compressor manufacturers cared about, and still do, is that their compressors are not being slugged with liquid due to faulty installation pratices.
"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis de Toqueville, 1835
Ha..ha..ha..good one use the label and wrap it around the suction line ...when the mountains turn blue your good....
Originally Posted by itsiceman