"HL" wrote in message news:gdvpd.2205$cE3.1333@clgrps12...

"Steve@carolinabreezehvac" wrote
in message ...

"HL" wrote in message
news:Xbrpd.3148$VL6.784@clgrps13...

"Steve@carolinabreezehvac"
wrote
in message ...

"HL" wrote in message
news:5Zfpd.1669$VL6.466@clgrps13...
If the temperature difference between the plenum and a duct is 8F
(ie:
Plenum is at 120F duct at register is 112F) can this be translated
into
duct
efficiency?


No.

Why?



Easy enough....what you ask, as you ask, translates to no.

Now, had you said, after a run time of XX minutes, with a duct run of XX
feet, with a heat rise of XXX degrees, and a delta of XX with a velocity
of
XXX FPS can this translate to a duct efficiency...and the answer would
have
been a possible yes.
There is a bit more info that would be needed as well, such as duct
construction, age, diameter.......

Otherwise,no.

8 degree loss on a run of say.....30 feet or less isnt enough to worry
about.

That's really what I needed to know.

Depending on how long the run time was, your delta with be less or
greater...so...as you ask...no.


Thanks, the run is about 30 feet, duct size is 8x14, run time was about 5
mins.


Not really long enough to heat the duct to plen temp,but not a bad drop. If
the duct is not insulated, insulate it to R6 per code, and things get
better.