[Equest-users] Modeling Reverse Acting TStat EF

[Darryl Kasun via Equest-users]

Hi everyone,

Have these systems modeled now that they are showing unmet clg hours and
the exhaust fans are turning on when temp is above 80F.

Here's a summary of the inputs required to achieve:

- fan schedule at BOTH system and zone level to be set to always off (0)
- night cycle fan control set to "cycle on any"
- clg rate very low (1 btu/hr)
- clg t-stat required

Thanks again everyone for your help.

Darryl

On Wed, Oct 19, 2016 at 1:08 PM, Darryl Kasun <darryl.kasun at gmail.com>
wrote:

> I do have a clg t-stat schedule set at 80F for all hours.  I have tried
> changing the fan schedule to undefined and to on for all hours and am still
> met with the fan not turning on at all.  The original fan schedule to keep
> the fan off had zeros for all hours.
>
> How to I check the custom hourly output reporting?
>
>
>
> On Wed, Oct 19, 2016 at 12:43 PM, Nicholas Caton <
> Nicholas.Caton at schneider-electric.com> wrote:
>
>> Immediate thought: Have you set a cooling thermostat schedule for the
>> zone with 80F at all hours?  That would explain both the lack of unmet
>> hours and no calls for conditioning (fan operation).
>>
>>
>>
>> If there is a thermostat schedule, did you confirm the fan is never
>> operating via custom hourly output reporting?  Do you have a system fan
>> schedule forcing OFF behavior with zeroes and/or -1’s?  If so, try forcing
>> ON with 1’s and/or just not defining a fan schedule at all to permit system
>> fan operations when called for.
>>
>>
>>
>>
>>
>> *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]
>>
>>
>>
>>
>>
>> *From:* Darryl Kasun [mailto:darryl.kasun at gmail.com]
>> *Sent:* Wednesday, October 19, 2016 1:18 PM
>>
>> *To:* Nicholas Caton <Nicholas.Caton at schneider-electric.com>
>> *Cc:* Brian Fountain <bfountain at greensim.com>; Julien MARREC <
>> julien.marrec at gmail.com>; equest-users <equest-users at lists.onebuildin
>> g.org>
>> *Subject:* Re: [Equest-users] Modeling Reverse Acting TStat EF
>>
>>
>>
>> Hi everyone,
>>
>>
>>
>> Thanks again for all your input.
>>
>>
>>
>> I've run into a snag.  I cannot seem to get the fan to turn on when the
>> temp > 80 degF.  When I look at some of the reports I see that there is no
>> reported unmet clg hours for this zone which is a red flag - not sure why
>> this is.  There is a sizable clg load in this zone: 65 MBH.  I do see on
>> the SS-F that the max zone temp hits 86.1 degF.  Any thoughts?
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> On Tue, Oct 18, 2016 at 4:00 PM, Nicholas Caton <
>> Nicholas.Caton at schneider-electric.com> wrote:
>>
>> Hey Darryl,
>>
>>
>>
>> This turned into a big response, but it seems the problem we’re trying to
>> help solve is a moving target!
>>
>>
>>
>> 1.       The advice to enter something nominal but tiny for cooling
>> capacity, to avoid autosizing & prevent airstream cooling, is based on the
>> earlier statement that you do not intend to cool the airstream making up
>> the exhaust.  Going the other route of just making it “free cooling”
>> (EIR=0) goes against your goal of modeling reality as now the exhaust
>> “makeup” airstream is being conditioned on its way in, resulting in milder
>> interior temperatures for determining hourly zonal heat transfers.  An
>> equally viable alternative I generally prefer to “lock out” cooling
>> operations by the way is an airside system COOLING-SCHEDULE with hourly
>> values of zero.  An expected side effect of of crippling/breaking your
>> PSZ’s cooling capacity with a tiny number is that you will end up with a
>> justifiable quantity of unmet cooling hours – so expect & make note of that
>> swing in unmet hours so you can quantify &  parse it out later for your own
>> QC/documentation.
>>
>> 2.       Based on the reference help entries, I’m concerned the
>> night-cycle-ctrl inputs are intended specifically for the inverse case only
>> (reacting only to provide heating when the system is off.  I think the
>> effect you’re looking for (turning on only when thermostat calls request
>> it) can be achieved for PSZ by simply not defining a fan schedule
>> (right-click, default that dropdown field).  *Either way*, you can &
>> should check/verify intended system operation via custom hourly reports for
>> the associated system & control zone – include hourly zone temperatures,
>> associated tstat setpoints, and something like fan operation/cfm to verify
>> if the system is only operating when intended.
>>
>> 3.       I’m not certain zonal exhaust inputs are necessary at all if
>> you are modeling a 100% OA PSZ, but be cautious you aren’t ending up
>> unintentionally “double-counting” fan energies between your PSZ fan power
>> inputs and your zonal exhaust power inputs (or lack thereof).  I think you
>> can “zero out” the zonal kW/cfm or else make it a very tiny number if you
>> do decide zonal exhaust inputs are needed.
>>
>>
>>
>> Ah… The fact you intend to model hot water unit heaters probably throws a
>> wrench into the advice/discussion so far…
>>
>>
>>
>> “Furnace” generally implies gas combustion heating in doe2/eQUEST.
>> That’s not what you want for hot water heating.
>>
>>
>>
>> If it’s fair to assume the space is well-mixed during heating scenarios
>> (i.e. not much stratification), then you can probably get by with
>> accounting for the associated unit heater by specifying hot water
>> baseboards with appropriate heating capacity in the zone.  Have them
>> controlled by a heating temperature schedule (sounds like you want this set
>> to 60F all the time).  You might want to specify the associated loop and
>> boilers/meters first so that you can assign those in the same step.
>> Downside to layering in baseboards as an approach is the unit heater fan
>> energies won’t get picked up explicitly – the heat those contribute will
>> instead be supplied by the HHW loop, and the energies associated with their
>> fan operations for air circulation will not be picked up automatically.
>> You could layer that in however (if it’s pertinent) by doing an hourly
>> report to identify when baseboards are in operation (delivering heat), then
>> assigning that to the space as an equipment load, capturing the heat
>> contributions and electricity consumption.
>>
>>
>>
>> If accounting for exhaust and unit heater fan energies operations
>> separately/distinctly is a major priority… you’ll probably need to re-think
>> the broader approach & system type selection.  UHT is an attractive option
>> for picking up unit heater operations explicitly and clearly on its own,
>> but that system type affords no capacity to handle OA/exhaust.  You’d
>> either need to accomplish the exhaust/damper operations at the zonal level
>> (spoon-feeding expected operations as a fractional or ON/OFF schedule since
>> we’ve established thermostat schedules are not presently an option).  You
>> could alternatively pair UHT’s with an airside-system-based approach to the
>> exhaust/damper operations (like the PSZ we’ve been discussing) if you split
>> your zone/spaces geometrically to afford separations to assign different
>> systems to, thermally connected with airwalls.  Advantage to this approach
>> is the flexibility to separate the conditioned volume if air mixing is not
>> going to be stellar (stratification expected) during heating.
>>
>>
>>
>> Hope this helps steer the ship!
>>
>>
>>
>> ~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]
>>
>>
>>
>>
>>
>> *From:* Darryl Kasun [mailto:darryl.kasun at gmail.com]
>> *Sent:* Monday, October 17, 2016 1:26 PM
>> *To:* Nicholas Caton <Nicholas.Caton at schneider-electric.com>
>> *Cc:* Brian Fountain <bfountain at greensim.com>; Julien MARREC <
>> julien.marrec at gmail.com>; equest-users <equest-users at lists.onebuildin
>> g.org>
>>
>>
>> *Subject:* Re: [Equest-users] Modeling Reverse Acting TStat EF
>>
>>
>>
>> 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
>>
>> >
>>
>> > _______________________________________________
>>
>> > Equest-users mailing list
>>
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>>
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