You might consider switching to a “built-up” air
handler instead of Unitary so you can control the heating coil with setpoints
placed on the coil outlet. Unitary system is hard-wired to try and
meet the zone’s load.
From:
EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On
Behalf Of Edward G. Lyon
Sent: Monday, August 23, 2010 3:25 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Controlling Heating Discharge
Temperature
Well this situation is a little more complex,
because this is a direct fired gas heater. The air flow remains constant, but I
have data showing that the unit can't heat to the rated capacity. If I mess
with efficiency (don't know where to poke to change it anyway, the field
equipment derating is not constant but varies with outdoor temperature) I loose
total gas used and no longer have a simple relationship for added moisture.
Ned Lyon, P.E. (MA)
Staff Consultant
Simpson Gumpertz & Heger
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com
-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
On Behalf Of Richard Raustad
Sent: Monday, August 23, 2010 5:15 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Controlling Heating Discharge Temperature
To answer your question, the sensible load request is independent of
equipment efficiency. But shouldn't you be changing the equipment
performance to match what you see in the field instead of modifying the
load to be met? If you reduce the load on a "non-defective" equipment
model, the equipment PLR will be reduced and you will not get what you
are finding in the field. If you are not getting the rated heating
capacity in the field, lower the capacity while holding the energy use
of the equipment at the rated energy use (i.e., lowering the efficiency
while reducing the capacity will give the same energy use of the rated
equipment while simulating a loss of capacity).
Edward G. Lyon wrote:
>
> Ok, so what I have to do is calculate my own load and apply that as a
> "Sensible Load Request" to a "Unitary HVAC" object. This
reduces
> heating and lowers the supply air temperature so I can simulate the
> defective operation of the field equipment I am looking at. The
> question now is does this "Sensible Load Request" include or
exclude
> the efficiency of the equipment?
>
> *Ned Lyon, P.E. (MA)**
> *Staff Consultant
>
> *SIMPSON GUMPERTZ & HEGER** *
> 781.907.9000 main
> 781.907.9350 direct
> 781.907.9009 fax
> www.sgh.com
>
> *From:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
*On Behalf Of *Don Shirey
> *Sent:* Monday, August 23, 2010 2:51 PM
> *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> *Subject:* Re: [EnergyPlus_Support] Controlling Heating Discharge
> Temperature
>
> This object is controlled by the thermostat setpoint and the
> calculated cooling/heating load for the control zone .... a setpoint
> manager is not used to control its operation.
>
>
> Edward G. Lyon wrote:
>
> I'm trying to control the heating discharge temperature of a
> Unitary:Furnace:HeatOnly. I'm having a hard time identifying the
> right node to control. I assume that it should be the Air Loop
> Outlet Node, but that does not seem to be working. Could it be the
> Zone Equipment Inlet Node?
>
> *Ned Lyon, P.E. (MA)**
> *Staff Consultant
>
> *SIMPSON GUMPERTZ & HEGER*
> *|* Engineering of Structures and Building Enclosures
>
> 41 Seyon Street, Bldg. 1, Suite 500
> Waltham, MA 02453
>
>
> 781.907.9000 main
> 781.907.9350 direct
> 781.907.9009 fax
> www.sgh.com <http://www.sgh.com>
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu
UCF - From Promise to Prominence: Celebrating 40 Years
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