Using Performance Data Spec Sheets to figure - Condenser Temp-Split
Testing whether the A-C System is delivering the Manufacture's BTUH
Rating by checking the Condenser's Delta-T
For the uninitiated, Delta-T is the difference between the air
temperature entering and leaving the outdoor A/C condensing unit. This
is a good diagnostic check because it measures the latent heat of
condensation as well as the sensible heat absorbed by the vaporizing
refrigerant in the indoor evaporator coil. I'm betting when you find out
approximately how many BTUH the A/C system is actually transferring
outside, you may be shocked.
18,400-btuh 17.7 Temp-Split
2Ton 24,800 22.8-F Temp-S
2.5T 30,200 19-F Temp -S
3 T 35,600 16-F Temp -S
3.5T 42,500 18-F Temp -S
4T 48,500 18-F Temp -S
5Ton 59,000 22-F Temp -S
By using the various units' base specification sheet data from the
dealer, you can determine if it is operating near its BTUH capacity rating.
The Base Spec sheets 12-SEER part no. 421 41 33301 03, Feb 2001. These
are the Comfortmaker® units, which are nearly identical to Heil® units.
While the "Performance Cooling Data" is listed at a 95-F outside
ambient temperature, you can adjust the indoor airflow to get the
Nominal BTUH Rating at the customer's normal indoor stat' temp' setting
and most outside temp' operating hours.
The compressor's Service Factor will handle the electrical load as long
as the discharge gas temp doesn't get above 225-F. The amp draw can vary
from 5.7 to 10.7 amps on my Kenmore window unit's spec sheet. The
nameplate rating is 7.5 amps at 115 volts, 10.5 that's 5 amps above the
rating, or 28½ % above the nameplate rating. [1.3 SF] It will handle up
to a 120-F outside ambient.
Take the "listed watts" and multiply by 3.413 to get the BTUH of the
motor heat additive to the listed BTUH, then divide by the condenser's
CFM. I didn't use any 1.07 multiplier additive. You can make up the
charts for 10, 12, and 14 SEER units for specific makes. One chart might
include many different makes. The 14 SEER is a whole different bucket of
bolts, as it uses a larger condenser and a very high CFM for a lower
temp-split. I question whether tech's can get them set-up well enough to
get the rated SEER.