Originally Posted by
Jerry Peck
The TD by itself is not telling you anything, and, unless you have reliable documentation which states otherwise, your numbers are WAY OFF, besides being meaningless numbers.
You're right Jerry.
Depending on what the latent (moisture) load is on the evaporator you could have a dry bulb temperature differential as low as 12º to 13º or as high as 21º to 23º.
If you want to take some readings of value don't take just dry bulb temperature readings include wet bulb readings with them.
With the wet bulb and dry bulb readings you can obtain a lot more valuable information.
If you have a half way accurate reading to determine how much air the fan is moving and an enthalpy chart you can plot how efficiently the equipment is operating breaking it down into total BTU's, Sensible BTU's, and Latent BTU's.
Measuring dry bulb temperatures alone only adds confusion to a situation where a piece of equipment might be operating properly.
Then you have the guys who try to measure temperature differential with a infrared thermometer.
