[Equest-users] Modeling Reverse Acting TStat EF

Mon Oct 17 11:04:02 PDT 2016

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

[cid:image002.png at 01D2286D.03968C70]
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<mailto:nicholas.caton at schneider-electric.com>
F  913.564.6380

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[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<mailto:julien.marrec at gmail.com>>; Darryl Kasun <darryl.kasun at gmail.com<mailto: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<mailto: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] On Behalf Of Julien MARREC via Equest-users

Sent: Saturday, October 15, 2016 3:41 PM

To: Darryl Kasun <darryl.kasun at gmail.com<mailto:darryl.kasun at gmail.com>>

Cc: equest <equest-users at lists.onebuilding.org<mailto: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<mailto: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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