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Discussion Starter · #1 · (Edited)
I realize there is no fixed or set answer, I am mainly looking for the opinion of a few hvac pros here. :)

If an HVAC system is over or under charged can that result in lower than "normal" cooling temperatures? (Would this also result in heating mode, cooler than normal heating temperatures?)

Below are the readings from my system in cooling mode. Do they appear on the surface to be correct or is output air of 44 too cold?

Outdoor Temp: 70F
Outdoor Humidity: 47%
Inside Humidity: 51%
Outside condenser: 80F
Suction line temp: 44F
Liquid Line temp: 66F
Air temp after A coil: 48F
Cold Air return temp: 70F
Tstat Setting: 73F

On an 84 degree day this week:

Suction: 43
Liquid: 72
Return: 69
Supply 48
Outdoor Temp: 84
Indoor Humid: 50
 

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Return at 70 with supply at 48 is marvelous. The delta T difference is usually 16-20 deg F and you got 21-22F. I would have to be there to see the duct size/air flow etc but the rest seems OK from here.If it was overcharged you would get white ice on the suction line to the outdoor unit. Your fan may need to be speeded up if that happens or use a less restrictive air filter.:thumbsup:
 

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Discussion Starter · #3 ·
Ok, thanks.

The fan is on high (2200CFM) and I am using a 20x25x3" filter.

It is a 5 Ton HP system.
 

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400 cfm/ton so you should be OK. If you have large ducts you can sometimes get over 20 deg Delta T w/o a problem.
 

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You got some problems with your readings!

Your liquid line temps are cooler then the oudoor temps.
Not possible. Unless the is a restriction before the point you measure the temp at.
Or your probes aren't accurate.

Even with the improements you made on your dut work.
Unless you actually measued the CFM, or stati pressure. Don't bet that your moving 2200 CFM in cooling mode.

The temp differences you post are good for the ambient conditions you posted.
 

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Discussion Starter · #7 ·
The temperature probe for the liquid line are immediately after the A coil.
The temperature probe for the suction line is also immediately after the A coil.
 

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Inside, or outside of cabinet?

If outside.
Its indicating flash gas.
 

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Discussion Starter · #9 · (Edited)
Inside the cabinet.

They are physically attached to the copper line then insulated (with tape) so as not to be skewed by the inside cabinet ambient temperature. I figured it would always be a few degrees warmer than the return temperature, with the closer it being to the return temperature a better indication of proper transfer of cool/heat.

I cant find the photos I took of the temperature install at the moment.

Real time info is at: http://enviro.onlinedesk.net
 

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The liquid line sensor should be outside the cabinet.
Insulation only slows down the transfer of heat. it doesn't stop it.

Return air sensor should be in the return plenum or just after the air filter, so as not to be effected by radiant heat in the winter.
 
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Discussion Starter · #11 ·
The liquid line sensor should be outside the cabinet.
Insulation only slows down the transfer of heat. it doesn't stop it.

Return air sensor should be in the return plenum or just after the air filter, so as not to be effected by radiant heat in the winter.
I'll move the liquid sensor out of the cabinet.

The return sensor is before the filter, in the center of the drop down box.
 

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Ok, I wasn't sure where you had the return sensor.
 
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