[Equest-users] Modeling Reverse Acting TStat EF

Mon Oct 17 11:26:19 PDT 2016

Hi everyone - thank you so much for the replies.  Just wanted to provide as
a summary as to what I've modeled thus far - pls comment if you have any:

*SYSTEM LEVEL:*

- Modeled the reverse acting t-stat system as a PSZ with the following
inputs at the system level:
- Control zone is the zone the supply fan serves
- Supply fan kW/CFM equals that of the EF
- Delta T across supply fan = 0
- Supply fan schedule is on/off type with default off for all hours
- Night Cycle Control: On Any
- min outside air ratio = 1.0
- CLG Cap left blank
- EIR = 0

*ZONE LEVEL:*

- HTG/CLG design temps are 60/80 degF;
- E/A control is "No Airflow Tracking"
- E/A flow matching the flow of the EF (11,000 CFM)
- E/A source: infiltration
- Max clg rate left blank

*QUESTIONS REMAINING:*

- Can I simply leave the CLG capacity to be auto-sized?  Brian you had
mentioned to put in a minimal value for this input but I do not understand
why.
- This zone also has HW UHs serving it - how to I implement them?  I see at
the system level there's an option for the Zone Heat Source to be furnace
which provides the opportunity to account for a UH's fan energy but looks
like a furnace cannot be connected to a HW loop.
 - Any advice of thermostat type?

Thanks again
Darryl Kasun

On Mon, Oct 17, 2016 at 11:04 AM, Nicholas Caton <
Nicholas.Caton at schneider-electric.com> wrote:

> Hey Brian,
>
>
>
> You’re absolutely right – I should have double-checked before posting.  In
> my mind’s eye, I recalled assigning a temperature schedule to zonal exhaust
> inputs, but it does appear I misremembered and that isn’t a direct option.
>
>
>
> Tricking an airside system as you’re describing into the intended behavior
> must be how I’ve managed this in the past.  A thermostat schedule is
> minimally needed at the system to define the intended “trigger
> temperatures,” and one could optionally also specify a fan schedule to go
> beyond intermittent and enforce off/on hours as might happen in the real
> world via tstat + relays.
>
> ~Nick
>
>
>
> *Nick Caton, P.E., BEMP*
>
>   Senior Energy Engineer
>   Energy and Sustainability Services
>   Schneider Electric
>
> D  913.564.6361
> M  785.410.3317
> E  nicholas.caton at schneider-electric.com
> F  913.564.6380
>
> 15200 Santa Fe Trail Drive
> Suite 204
> Lenexa, KS 66219
> United States
>
> [image: cid:image001.png at 01D189AB.58634A10]
>
>
>
> -----Original Message-----
> From: Brian Fountain [mailto:bfountain at greensim.com]
> Sent: Monday, October 17, 2016 9:55 AM
> To: Nicholas Caton <Nicholas.Caton at schneider-electric.com>; Julien MARREC
> <julien.marrec at gmail.com>; Darryl Kasun <darryl.kasun at gmail.com>
> Cc: equest-users <equest-users at lists.onebuilding.org>
> Subject: Re: [Equest-users] Modeling Reverse Acting TStat EF
>
>
>
> Does this mean the exhaust fan can cycle based on zone temperature?   I
> had thought that the exhaust fan schedule was just on/off, on/off/flag and
> fraction. That means you have to pre-define the expected schedule rather
> than having the EF respond to the hourly space timestep temperature.
>
>
>
> What we have done in the past is to model the EF as a PSZ with the fan
> power as the supply fan power and the "indoor fan mode" as intermittent.
> Cooling capacity set to a small non-zero value (as zero invokes
> auto-sizing).
>
>
>
>
>
>
>
>   Original Message
>
> From: Nicholas Caton via Equest-users
>
> Sent: Monday, October 17, 2016 10:39 AM
>
> To: Julien MARREC; Darryl Kasun
>
> Reply To: Nicholas Caton
>
> Cc: equest-users
>
> Subject: Re: [Equest-users] Modeling Reverse Acting TStat EF
>
>
>
> From: Nicholas Caton
>
> Sent: Monday, October 17, 2016 9:38 AM
>
> To: 'Julien MARREC' <julien.marrec at gmail.com>; Darryl Kasun <
> darryl.kasun at gmail.com>
>
> Subject: RE: [Equest-users] Modeling Reverse Acting TStat EF
>
>
>
> Yep - Julien has the right idea!
>
>
>
> The other input of interest for your case is that at the same input
> screen, you can select the exhaust source as "infiltration," which means
> the associated makeup airstream = outside conditions.
>
>
>
> ~Nick
>
>
>
> Nick Caton, P.E., BEMP
>
> Senior Energy Engineer
>
> Energy and Sustainability Services
>
> Schneider Electric
>
> D 913.564.6361
>
> M 785.410.3317
>
> E nicholas.caton at schneider-electric.com
>
> F 913.564.6380
>
> 15200 Santa Fe Trail Drive
>
> Suite 204
>
> Lenexa, KS 66219
>
> United States
>
>
>
>
>
>
>
> -----Original Message-----
>
> From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
> <equest-users-bounces at lists.onebuilding.org>] On Behalf Of Julien MARREC
> via Equest-users
>
> Sent: Saturday, October 15, 2016 3:41 PM
>
> To: Darryl Kasun <darryl.kasun at gmail.com>
>
> Cc: equest <equest-users at lists.onebuilding.org>
>
> Subject: Re: [Equest-users] Modeling Reverse Acting TStat EF
>
>
>
> Zonal exhaust fan has an option to control that on a temp schedule if I
> recall correctly.
>
>
>
> Open the zone, tab "outside air" then at the right you can specify a zonal
> exhaust fan. (All this from memory so might differ slightly)
>
>
>
> Cheers,
>
> Julien
>
>
>
> Envoyé de mon iPhone
>
>
>
> > Le 15 oct. 2016 à 20:57, Darryl Kasun via Equest-users <
> equest-users at lists.onebuilding.org> a écrit :
>
> >
>
> > Hi eQUESTers,
>
> >
>
> > First off, you probably will not likely appreciate this and I'll preface
> this with saying that I'm a total bandwagon jumper but I am okay with that.
>
> >
>
> > GO JAYS!!!
>
> >
>
> > Now that that's out of the way I am trying to model a very simple system
> that I'm sure many of you have modeled before.
>
> >
>
> > I have a zone that has an exhaust fan in it. When the temp. reaches
> above 80 degF, an exhaust fan turns on and a damper opens to draw OA into
> the zone.
>
> >
>
> > I've been fooling around with a few systems trying to figure out a good
> way to model this but haven't come up with one yet.
>
> >
>
> > Let me know if have any recommendations.
>
> >
>
> > Thanks!
>
> > Darryl
>
> >
>
> > _______________________________________________
>
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>
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>
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