[Trace-users] Multiple Ground source Heatpump in one alternative

[Sturm, Eric]

Alex,

The interface will allow you to specify more than one ground heat exchanger, however the results presented for the second loop (as determined by the order of entry) cannot be used.  Only one may be simulated per alternative.  In your results from an error scan, you should see a fatal error associated with multiple ground loops.

Eric Sturm
Applications Engineer
Trane Commercial Systems
Ingersoll Rand
3600 Pammel Creek Rd
La Crosse, WI 54601

Office:  +1.608.787.3736
Fax:  +1.608.787.3005
Email:  esturm at trane.com<mailto:esturm at trane.com>
Website:  www.trane.com

From: trace-users-bounces at lists.onebuilding.org [mailto:trace-users-bounces at lists.onebuilding.org] On Behalf Of AChapin at sriregistrar.com
Sent: Wednesday, November 28, 2012 3:41 PM
To: trace-users at lists.onebuilding.org
Subject: [Trace-users] Multiple Ground source Heatpump in one alternative

Eric,

I am surprised to hear you say that TRACE will not allow two separate ground loops in a single file because if you create multiple cooling plants with ground loops, you are allowed to specify different parameters for "TLoop Ent Bldg" under Plant Controls, Geothermal Loop. When you run the model, you even get different energy use results for each cooling plant (GSHP) when you have two identical rooms with one assigned to each cooling plant (since the temperature of the ground loop is different based on TLoop Ent Bldg). This implies that there are two separate loops, otherwise the one loop would have two different entering temperatures simultaneously.

Catalina, does that address the question that you asked?

Alex N. Chapin, LEED AP BD+C
Sustainability Program Engineer

SRI Quality System Registrar
300 Northpointe Circle, Suite 304
Seven Fields, PA 16046
phone: 724.934.9000 x619; fax: 724.934.9145
AChapin at sriregistrar.com<mailto:AChapin at sriregistrar.com>

Date: Tue, 27 Nov 2012 21:48:11 +0000
From: "Sturm, Eric" <esturm at trane.com<mailto:esturm at trane.com>>
To: "Caballero, Catalina" <ccaballero at jalrw.com<mailto:ccaballero at jalrw.com>>
Cc: "'trace-users at lists.onebuilding.org'"
                <trace-users at lists.onebuilding.org<mailto:trace-users at lists.onebuilding.org>>
Subject: Re: [Trace-users] Multiple Ground source Heatpump in one
                alternative
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Catalina,

This is a complex scenario to model in TRACE 700 and I wanted to shed some light on what is possible and not possible.

The limitations you're finding are related to how system coils are assigned to equipment (plants), and ground heat exchangers.  TRACE 700 can only model a single ground heat exchanger per alternative and system coils (e.g. cooling and heating coils) are assigned to a plant, rather than an individual piece of equipment.  In your scenario, you may have one or two ground loops but you'll only be able to model a single loop in the alternative.  This limitation prevents you from modeling the systems independently.

If you create two ground source heat pump pieces of equipment, you'll still need to assign these to a single plant.  Doing so does not allow you to independently operate each plant based upon system coil load because cooling and heating coils are assigned to plants rather than equipment.  The sequencing options will not help you in this instance.

To model this system, you'll need to make a ground source heat pump system as shown in the User's Manual.  You can make a single cooling plant (water source heat pump equipment type) and modify the energy rate and ground loop information as you desire.  You may wish to use a composite energy rate the best represents all heat pumps on the ground loop(s).

I suspect that the information you received from C.D.S. is correct in that you can model two separate heat pump plants, but you cannot model two separate ground loops in a single file.

Regards,
Eric Sturm
Applications Engineer
Trane Commercial Systems
Ingersoll Rand
3600 Pammel Creek Rd
La Crosse, WI 54601

Office:  +1.608.787.3736
Fax:  +1.608.787.3005
Email:  esturm at trane.com<mailto:esturm at trane.com>
Website:  www.trane.com

From: trace-users-bounces at lists.onebuilding.org<mailto:trace-users-bounces at lists.onebuilding.org> [mailto:trace-users-bounces at lists.onebuilding.org] On Behalf Of Caballero, Catalina
Sent: Tuesday, November 27, 2012 2:57 PM
To: 'trace-users at lists.onebuilding.org'
Subject: [Trace-users] Multiple Ground source Heatpump in one alternative

Good afternoon,

I'm trying to find out a way to model 2 ground source heat pumps in an alternative. One of these systems serves an exhibition spaces, and the other one serves a mechanical room. When I call CDS some representatives say it's possible, others don't think so, making it more confusing. Anybody has experience with this issue?

Regards,

Catalina Caballero, AIA. Assoc., LEED GA.
Johnson, Avedano, Lopez, Rodriguez & Walewski
Engineering Group, Inc.

2510 NW 97th Avenue, Suite 220, Miami, Florida 33172
Tel. (305) 594-0660 Ext. 217 Fax (305) 594-0907

Visit us online: www.jalrw.com<http://www.jalrw.com/>

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