RE: [EnergyPlus_Support] Steam Boiler GetSpecificHeatGlycol warning

Thank you Richard. I have the correct pump. I will review what you sent to me and see if I can work out a solution.

The standard hotel room PTAC draws return air from the room across the cold coil, mixes outdoor air between the fan and the cold coil, then supplies air to the room from the fan discharge (no dehumidification of outdoor air). With an external heater (hot water coil) heat is downstream of the fan. Heat pumps do the heating at the cold coil and adjacent to it for electric backup. The EnergyPlus PTAC is configured like a typical roof top unit where return and ventilation air are mixed before the coils. I usually introduce PTAC ventilation air as infiltration to compensate, but that doesn’t vary with equipment operation.

Ned Lyon, P.E. (MA, WV)
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 Richard Raustad
Sent: Friday, March 15, 2013 8:01 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Steam Boiler GetSpecificHeatGlycol warning

Did you use the correct pump?

Pump:VariableSpeed:Condensate,
       \memo This pump model is described in the ASHRAE secondary HVAC toolkit.
       \memo Variable Speed Condensate pump for Steam Systems

It can be frustrating to manually create plant loops. But really, they are not that hard to understand. For example, I have used this " single cooling and heating plant" many times to connect to a single water based equipment model (usually VRF). Bottom line, since I already have this plant available it is very easy to add to any input file using macro language.

##fileprefix C:\MyProjects\EnergyPlus\EnergyPlus\Inputs\
##include VRFSinglePlantLoopBoilerTower.idf

The only connection between this stand alone plant input file and the main input file is here (this is in the main input file):

AirConditioner:VariableRefrigerantFlow,
    VRFCondInNode,           !- Condenser Inlet Node Name
    VRFCondOutNode,          !- Condenser Outlet Node Name

I'm including both files for review.

Main input file: VariableRefrigerantFlow_5Zone_HeatRecovery_WaterCooled.imf
Plant library: VRFSinglePlantLoopBoilerTower.idf

Using this method, basically from a library of plant configurations, it becomes easy to implement.

I developed the PTAC model in E+ and do not understand your comment on configuration.

On 3/14/2013 5:18 PM, Edward G. Lyon wrote:

I cobbled together a steam boiler system by robbing 5ZoneSteamBaseboard.idf so I could supply one steam baseboard in my model. I now fully understand how little I know about piecing together a functional mechanical system from EnergyPlus components without using templates (translation: what a pile of junk to add just to run a little radiator). I did not autosize anything because I know the radiator flow rate already. PlantPumps:CalcPumps is throwing a GetSpecificHeatGlycol warning because it has a 107C temperature fluid. I suspect that the plant is so oversized that it supplies steam to the pump, but I would appreciate any suggestions for resolving this without reverting to an autosized solution.

Also, any references that simply explain how to take a set of fans, pipes, and coils in a box and make the appropriate nodes, loops, branches and controls for EnergyPlus would be appreciated, I’ve never seen a PTAC in the field that actually looks like the EnergyPlus PTAC most people use, so I should probably build my own…

Ned Lyon, P.E. (MA, WV)
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

--

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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