[Equest-users] HVAC System Lockout

Arpan Bakshi arpanbakshi at gmail.com
Fri Feb 4 13:49:47 PST 2011


Cory, I would recommend a test run, detaching all schedules, just to let the
auto-size engine do its work; you should see comparable loads. I find
uncoordinated schedules can cause all kinds of ruckus.

On Fri, Feb 4, 2011 at 4:43 PM, Cory Duggin <crduggin at gmail.com> wrote:

> Based on what you have said, I think I just need a new heating and cooling
> schedule.  I found them in my component tree, but I am not sure how to do
> what I want because the annual schedule only specifies an ending month and
> day.  How do I know when that schedule starts?
>
>
> On Thu, Feb 3, 2011 at 9:24 PM, Nick Caton <ncaton at smithboucher.com>wrote:
>
>>  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
>>
>>
>>
>> [image: cid:489575314 at 22072009-0ABB]**
>>
>> * *
>>
>> *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
>>
>>
>>
>> [image: cid:489575314 at 22072009-0ABB]
>>
>> * *
>>
>> *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:* 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
>>
>
>
>
> --
> Cory Duggin, EI
> Tennessee Tech University
> Graduate Research Assistant
> Mechanical Engineering
>
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-- 

Arpan Bakshi
646 704-2880
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