Is my AC charged properly?
I just had a new 13 SEER 2 ton ac unit installed. New A coil and lines. The temperature drop is right around around 20 degrees, but the line temps make me wonder if it is fully charged. On my 30 year old 5 SEER unit when it worked properly, the large line was cold and the small line was hot to the touch. On the new unit the large line is cool, but not cold, and the small line is warm, but not hot. I guess I am trying to figure out if this is normal or if the installer might have shorted me on the refrigerant?
The house is cooling normally as the temp is 55 degrees coming out of the register on a 83 degree day, but I am worried if it will be able to cool the house on a 100 degree day. Should I call the guy back out? Is there anything else I can check to determine if it was done properly?
Do a temperature in the return, and a temperature in the supply.
Originally Posted by mpoore
Is the unit in the attic?
"Better tell the sandman to stay away, because we're gonna be workin on this one all night."
"Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."
"Just get it done son."
That's the way they're supposed to run. Don't worry about it.
Sounds like its working good, let it be
Your old unit was probably overcharged causing it to have no superheat
the large line being cold indicates too low a superheat from being overcharged.
the small line being warm, as in slightly above outdoor temp is perfect, and an indication of a clean condenser coil, and a good charge.
if the small line is hot to the touch, unless it's 125F outside, indicates an inefficient condenser, that is likely quite dirty, and possibly overcharged.
The TRUE highest cost system is the system not installed properly...
The three big summer hearththrobs...
The A/C repairman
Thats where the beer can cold charging method came from ,now days we use subcool and superheat the small liquid line should be about 5 to 10 degees above outdoor temp
We really need change now
Thank you all for the quick replies.
The unit is not in an attic. It is ground level on the north side of the house.
The consenus seems to be that its fine. Sounds like I am not used to a well running system.
If you are maintaining <50%RH in the living space after a couple hours high cooling loads, you probably have a adequate charge of refrigerant and also correct air flow rate through the cooling coil. <50%RH is important for comfort and to growing mold/ dust mites.
Also critical for indoor air quality is purging indoor polutants and renewing oxygen. Mechanically adding an air change of filtered fresh air in 4-5 hours is ideal when the home is occupied.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
The unit is operating properly.
Originally Posted by mpoore
[ Only call the tech out, If you wish to add another unit. ]
However, the unit operating properly is no not the most significant parameter in determining whether is can cool to your satisfaction on a 100 degree day.
If your house is 2,600 square feet in Canada, it might be adequate 97% of the time.
If your house is 1,800 square feet in IOWA, it might be adequate ( < 80'F room temp.) 87% of the time in mid-summer.
If your house is 1,800 square feet in Houston it might be adequate 65% of the time in mid-summer.
It's Not Rocket Science, But It is SCIENCE
with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE
Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities
Okay, get a humidity gauge; hardware stores usually have them at a very low cost.
I just had a new 13 SEER 2 ton ac unit installed. New A coil and lines. The temperature drop is right around 20 degrees, but the line temps make me wonder if it is fully charged.
The house is cooling normally as the temp is 55 degrees coming out of the register
on a 83 degree day, but I am worried if it will be able to cool the house on a 100 degree day. Should I call the guy back out? Is there anything else I can check to determine if it was done properly?
A 2-Ton; R-410A; 13-SEER; @75F indoor temp & wet bulb 63F or, 51% relative humidity; Goodman data; temp drop is 19F; 75-19 is 56F.
The humidity may be a little less than 51% which would result in an additional 1 degree drop; 'IF' the humidity is 51% then, I'd say the airflow is ballpark close enough to 400-CFM per/ton, or 800-CFM.
Humidity levels have the major effect on the temp-drop numbers; a higher humidity means less drop, low humidity yields increased drop numbers.
Additionally, you're taking the temp at a register therefore, the duct run would have some heat-gain resulting in the reality that the temp-drop is lower than 55F directly after the coil.