[Equest-users] HVAC System Lockout

Nick Caton ncaton at smithboucher.com
Thu Feb 3 19:24:07 PST 2011


Whoah buddy =)!

 

First, let me give the preface that I'll be passing the 70hr mark for
this workweek tonight, so I'm kind of in zombie-mode right now XD!

 

Okay, I reckon you're hunting rabbits with a  bazooka by resorting to an
absorption chiller/boiler setup to approximate your gas furnace!  I'd go
ahead and save your work in a separate file for reference, then I'd step
back to the wizards to try a packaged single-zone furnace with DX
cooling for your 2-story zone, and a single-zone heatpump (DX/DX) for
your garage.  Make the systems "on" 24hrs with intermittent fan
operation, and be sure you're not specifying "system per zone."  Use the
shell wizard to be sure the zones are assigned to the right system.  

 

If you wish, you can restrict heating and cooling availability for each
system, the way a residential thermostat has "heating" and "cooling"
modes, with a COOLING-SCHEDULE and HEATING-SCHEDULE.  By default,
heating and cooling are generally available whenever they're called for,
but you can edit that without going to a chiller/boiler system ;).

 

If you are finding your building is flip-flopping between heating and
cooling hour-to-hour in the dead of summer, it might be a sign other
items are off... check your envelope constructions/layers, and note that
oversimplifying geometries/spaces (i.e. - one per floor) may result in a
lot of thermal mass from partitions being excluded that would otherwise
be a stabilizing presence.

 

I'm copying the eQuest list, because I will be of little use to you
others in the next 24 hours...  Our strength is in numbers, so do keep
everyone in the loop as you work through this and you'll get the best
chance of quality assistance - best of luck =)!

 

Back to the grindstone...

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

From: Cory Duggin [mailto:crduggin at gmail.com] 
Sent: Thursday, February 03, 2011 1:23 PM
To: Nick Caton
Subject: Re: [Equest-users] HVAC System Lockout

 

I am modeling a two story house with a one story garage that has been
converted into a conditioned space.  It is setup so there are 3 zones.
One in each floor of the two story part and then the garage.  The real
system in the house is one unit for the two story part that has gas
heat, and the garage has its own small heat pump unit.  Since most
people don't flip their thermostat back and forth between heat and cool,
I don't want my systems suddenly switching to heat for an hour in the
middle of summer because one of the zones got below set point.  I have
now changed the system to a chilled water loop and a hot water loop.
Where the hot water is provided by a natural draft boiler and the
chilled water is provided by a single effect absorption chiller.  I am
trying to create a loads file that will have the load on the chiller
rather than the load on each coil for each zone and also the heating
load for all the zones, but I don't want it to be able to change from
cooling to heating in the cooling season or vice versa.  Does that makes
sense?  Thanks

On Thu, Feb 3, 2011 at 11:19 AM, Nick Caton <ncaton at smithboucher.com>
wrote:

Cory, your query needs more description to include what you're trying to
model and what you've input, but if you've got simultaneous calls for
heating and cooling being handled, it sounds like you have either a
multi-zone system or multiple systems specified where you want only (1)
single-zone system.  

 

If I were trying to model the behavior of the HVAC in my apartment
accurately (a simple CV electric furnace with DX cooling controlled by a
single remote thermostat), I'd group all conditioned spaces and their
zones under a single system, taking care to assign the thermostat zone
where the thermostat actually resides - it's the zone highlighted red in
the graphic under the airside HVAC tab.

 

I'd suggest revisiting the quantity and type of system you've specified
first, and modify/reassign your systems/zones as necessary to see if
that's where the problem resides.  If you're still having troubles,
you'll need to provide a better description of what sort of system
you're trying to model (layman's terms are fine in this forum) and what
you've tried to specify on the model side.  Attaching your project's
.inp/.pd2 files may encourage others to help troubleshoot also ;).

 

Best of luck!

 

~Nick

 



 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com <http://www.smithboucher.com>  

 

From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of Cory Duggin
Sent: Wednesday, February 02, 2011 4:07 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] HVAC System Lockout

 

Is there a way I can create a schedule to lockout either the heating or
cooling system based on the time of year?  I am modeling a residential
system, so I don't want it to try and satisfy heating a cooling loads
simultaneously in different zones.  Thanks

-- 
Cory Duggin, EI
Tennessee Tech University
Graduate Research Assistant
Mechanical Engineering




-- 
Cory Duggin, EI
Tennessee Tech University
Graduate Research Assistant
Mechanical Engineering

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110203/0e172a37/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1459 bytes
Desc: image001.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110203/0e172a37/attachment-0001.jpeg>


More information about the Equest-users mailing list