[Equest-users] question about inefficiency of duct

[Paul Diglio]

Michael:

"if the air in duct is the same air as the air being supplied to the space, 
there is no net effect"?  What do you mean by net effect?

The duct heat loss/gain depends on the difference of the temperature of the air 
in the duct and the temperature of the air surrounding the outside of the duct.  
It is highly unlikely that these temperature will be the same.

Paul Diglio




________________________________
From: "McArdle, Mike" <Mike.McAardle at state.vt.us>
To: xiaoyang shi <xs2144 at gmail.com>; "equest-users at lists.onebuilding.org" 
<equest-users at lists.onebuilding.org>
Sent: Tue, March 29, 2011 5:39:40 PM
Subject: Re: [Equest-users] question about inefficiency of duct


Dear xiaoyang shi
 
It Depends on the temperature differentials between air in duct and space and 
insulation thickness 

 
But more importantly , if the air  in duct is the same air as the air being 
supplied to the space there is no net effect 

 
 
Thank you,  Sincerely,
 
Michael J. McArdle , P.E.
Buildings Engineer II, Project Manager 
State of Vermont, 
Buildings and General Services (BGS)
2 Governor Aiken Avenue
Montpelier, Vt. 05633
 
Office: 802-828-5650;  cell: 802-272-4828
 
From:equest-users-bounces at lists.onebuilding.org 
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of xiaoyang shi
Sent: Tuesday, March 29, 2011 5:37 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] question about inefficiency of duct
 
Hi folks,

In the winter time, some heat loss in HVAC is from duct.

What is the percentage of heat loss through the duct to the total building heat 
load, due to the inefficiencies of duct delivery system?

Thank you guys.
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