charging by superheat

[bharr07]

hello , as being a apprentice tech, i was hopeing to get some different views on how to charge by the superheat method , i went and finished hvac school over a year ago , and was taught somewhat the basics on charging that way , but now at this very small company i work for about 7 months now and with only one other technician , that never went to school and doenst have a clue what superheat is and he just charges the rule of thumb way +30 outide and -35 inside , anyway after so long now of not charging the right way i pretty much forgot superheat and subcooling methods , and was hopeing i could get some information other than the same old text book info(at least the text book i have does seem to make it very complicated ,mostly our company just works on residencial split systems , and single/double wide mobles, thanks in advance for any info in making the superheat meathod simple to understand .

[Edited by bharr07 on 11-14-2006 at 02:11 AM]

[r247yan]

I would just use this.. you will still need a good thermometer , gauges etc.. but this will guide you ..

http://www.rhvactools.com/serviceaids/superheatcard.htm

ryan

[amd]

http://www.refrigtech.com/charge.html

Get your hands on a superheat and R22 pt chart. (See website)

Superheat = Temperature rise above the saturation point of the refrigerant, at a given pressure.

1. Measure suction line pressure, find corresponding saturation temperature on chart.
2. Measure suction line temperature
3. Subtract saturation temperature from suction line temperature
4. Compare with chart

Remember TXV systems are not to be charged by superheat. You must run the system for several minutes before taking readings. Also note that low or high superheat does not necessarily imply that the charge is incorrect; a dirty filter/coil, incorrect blower speed or mismatched evap coil/orifice will alter pressure and temperature readings.

[billva]

check out the "For Your Interest" section for a wealth of info.

good luck.

[btuandkwh]

That's too bad that the shcool you attended didn't make sure you understood charging methods completely. The Tech College I graduated from had us repeat the process till we could do it blindfolded (i.e. without the book).
I've worked with guys that charge till "it feels cool enough"! (scary)
As most things,... practice makes perfect.

Good luck, and don't toss the book, it does come in handy.

[smokin68]

Register as a pro, this should be in the pro forum, where alot more advise can be given.

[RoBoTeq]

Originally posted by smokin68
Register as a pro, this should be in the pro forum, where alot more advise can be given.

This is good advice. There is a 15 post minimum for application to the Pro Tech forum. Get 15 posts under your belt discussing less technical issues and then apply to the Pro Tech forum.

[junkhound]

"worked with guys that charge till "it feels cool enough"

It has its' place in emergencies.

Actually charged the neighbors AC in August that way. Was putting my bag into the truck on the way toward the airport for a business trip when he stops over to ask if I could take a quick look at his no cool situation. He had already checked the filter, fans, coils, etc for dirt. Must have a slow leak - grabbed a R22 jug and the gauge but no time to get the type K (off in a different garage) and pulled in enough R22 for the pressure to look decent and the suction to 'feel' cool. Less than 10 minutes and no worry about missing the plane. Will check his system in the spring.
Payment not expected - but he brought over a bottle of "knob creek" when I got back.

[Furnace_dude]

Originally posted by bharr07
hello , as being a apprentice tech, i was hopeing to get some different views on how to charge by the superheat method , i went and finished hvac school over a year ago , and was taught somewhat the basics on charging that way , but now at this very small company i work for about 7 months now and with only one other technician , that never went to school and doenst have a clue what superheat is and he just charges the rule of thumb way +30 outide and -35 inside , anyway after so long now of not charging the right way i pretty much forgot superheat and subcooling methods , and was hopeing i could get some information other than the same old text book info(at least the text book i have does seem to make it very complicated ,mostly our company just works on residencial split systems , and single/double wide mobles, thanks in advance for any info in making the superheat meathod simple to understand .

[Edited by bharr07 on 11-14-2006 at 02:11 AM]

you can use the rules of thumb to get a vauge idea of what is happening, but i use the book ways too. like mentioned afore, talk about a few less technical issues and then join the edumakatid forum [pro's section] and then talk technical