DT

[hewitt]

Well u get the same DeltaT if u check temp.difference at return and in supply versus checking coming out of register and at return assuming there is no leaks in duct .Just want to get some feedback from other great techs.

[mark beiser]

It depends on how much heat gain/loss there is in the ductwork.
There are no perfect duct systems.

If you want to know that the equipment is doing, check at the equipment.

[hewitt]

That was my theory. Me and a few techs were basing our opinion or debating this and I said the guys on hvac talk will back this up.thanks.

[superd77]

An attic install will lose a couple degrees. Crawl space not so much

[beenthere]

Best taken at the unit. So you know what the equipment is doing. No way to know if the air in the duct is picking up temp by the time it reaches the register, unless you checked it at the unit anyway.

[dandyme]

@ equipment=equipment performance

@registers=system performance

as was stated previously, if you don't know how the equipment, you'll never know how the system is doing