[Equest-users] Water Loop HP system type fan power

James Hess JHess at tmecorp.com
Fri Mar 1 13:32:38 PST 2013


The default fan power in eQuest for water source heat pumps is not 0.000070 kW/CFM.

If you select the air source HP system type in the eQuest wizard, and then carry through to the Detailed Interface, you get what's posted below.

This combination of TSP (1") and overall efficiency of 53% results in fan power of ~ 0.221 watts/CFM.  The water source heat pump type uses 50% efficiency and TSP = 1.0, and results in a similar value of 0.235 watts/CFM.

If your point is that these are less than the criticized PTAC value of 0.3 watts/CFM, it certainly is.  Also, 4-P FCUs have default fan power values of ~ 0.18 watts/CFM because they assume 0.5" and 33% overall efficiency.

If a Proposed Design was based on these really low default eQuest fan power values, it may be possible for the Proposed Design to absorb the fan power of the DOAS without a significant adverse fan power penalty, or maybe none at all.  However, these default values, in my opinion, clearly assume equipment with zero external supply and return ductwork.  Consequently, I don't think they would be applicable unless you had that exact situation, which many projects do not.

I think the value that Tim quoted below of 0.4 watts/CFM is more "real world" for unitary systems with ductwork.  In fact, that matches exactly what I measured on the unit at my house.

If you are using appropriate fan power values for the Proposed Design unitary systems in the range of 0.40 watts/CFM, your Baseline has no allowance to counter the fan power of a DOAS, in fact, you are starting with negative savings (i.e. 0.4 vs 0.3) from the start with no consideration of the DOAS.

And this [neverending] thread continues ...


[cid:image004.png at 01CE1690.35CEA580]

Regards,

JAH

James A. Hess, PE, CEM, BEMP
Energy Engineer
TME, Inc.
Little Rock, AR
Mobile: (501) 351-4667

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Howe, Timothy
Sent: Friday, March 01, 2013 2:16 PM
To: Bishop, Bill; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Water Loop HP system type fan power

I typically see around 0.000400 on HP system.  Give or take a little bit depending on how you do your calc and what kind of electrical efficiency you assess to a fractional hp motor.

3 ton McQuay unit:

[cid:image002.png at 01CE168E.F19F2930]


Timothy Howe, MS, BEMP, LEED® AP BD+C
Mechanical Engineer
Stantec
61 Commercial Street
Rochester NY 14614
Ph:   (585) 413-5347
Fx:   (585) 272-1814
Cell: (585) 281-3223
stantec.com<http://www.stantec.com/>

The content of this email is the confidential property of Stantec and should not be copied, modified, retransmitted, or used for any purpose except with Stantec's written authorization. If you are not the intended recipient, please delete all copies and notify us immediately.

ü Please consider the environment before printing this email.

From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
Sent: Friday, March 01, 2013 3:06 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Water Loop HP system type fan power

The eQUEST default is .000070 kW/cfm for the HP system type. This is the same as the default for Unit Heaters, and seems really low. It is only 1/4th the Appendix G. baseline PTAC/PTHP fan power, which has been criticized as too low in another [neverending] thread.
Could there be an extra zero in there? (No, not the one on the end.)

Thanks,
Bill

[Senior Energy Engineer 28Jun2012]<mailto:wbishop at pathfinder-ea.com>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130301/d1fdaf69/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.png
Type: image/png
Size: 13493 bytes
Desc: image002.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130301/d1fdaf69/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.jpg
Type: image/jpeg
Size: 20869 bytes
Desc: image003.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130301/d1fdaf69/attachment-0002.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image004.png
Type: image/png
Size: 66739 bytes
Desc: image004.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130301/d1fdaf69/attachment-0005.png>


More information about the Equest-users mailing list