[Equest-users] HVAC System Lockout

[atowell at cxegroup.com]

Cory-

For annual schedules, they automatically start at the beginning of the year. If you need it to start at a certain time of the year, you'll first have to create one that ends just before your needed start date. Then you can designate when you want your schedule to end. I'm not sure how much sense that made, but I hope it helps!


Adam Towell
CxE Group, LLC
618-659-9461




From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Cory Duggin
Sent: Friday, February 04, 2011 3:44 PM
To: Nick Caton
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] HVAC System Lockout

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<mailto: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

[cid:image001.jpg at 01CBC482.FC7F39E0]

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: Cory Duggin [mailto:crduggin at gmail.com<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<mailto: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

[cid:image001.jpg at 01CBC482.FC7F39E0]

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> [mailto: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<mailto: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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