[Equest-users] Fwd: no heating loads to systems --part II

[Pasha Korber-Gonzalez]

Thanks Bill,

I do have specified 105 supply temp, 105 hot deck max temp, 50F reheat delta
T.  For some reason my results are very low for my ASHRAE baseline building
& they are showing virtually 1% heating energy consumption overall in my
building, and I have one standard effeicency boiler in the plant side.

This is what I know (by gut feel) the issue is--somewhere in the airside I
have either turned on or off some control or schedule--along with when I set
up the model using the wizard initial inputs they were for the proposed case
(water-to-water heat pumps-geothermal htg/clg & serving all spaces including
thermal displacement vent, natural vent zones (for htg baseboards), FC's
etc.  So----I am wondering if when I saved my file for the baseline model
and then switched the plant equip (chiller/boiler) & VAV sys if there is a
carry-over input from the HPsystems (or other) that is affecting the lack of
heating energy with the standard systems.

Not sure how to find a 'carry-over' input.  I have compared my input files
with examdiff program and couldn't find anything specific.

I've attached the non-corrupted files to this email...

pk

On Mon, Mar 8, 2010 at 8:54 AM, Bishop, Bill <wbishop at pathfinder-ea.com>wrote:

>  Pasha,
>
>
>
> For VAV systems you also have to specify the HEAT-SET-T (Hot Deck Max
> Leaving Temp) to enable the main air handler heating coil. You can’t just
> leave the field blank. For example, if your room supply air temperature is
> 90F and you have 30F reheat, enter 60F for the hot deck temp.
>
>
>
> Regards,
> Bill
>
>
>
> *William Bishop, EIT, LEED® AP **|** **Pathfinder Engineers & Architects
> LLP***
>
> Mechanical Engineer
>
>
>
> 134 South Fitzhugh Street
> Rochester, NY 14608
> T: (585) 325-6004 Ext. 114
> F: (585) 325-6005
>
> wbishop at pathfinder-ea.com
>
> www.pathfinder-ea.com
>
> P Please strive to live sustainably.
>  ------------------------------
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Pasha
> Korber-Gonzalez
>
> *Sent:* Monday, March 08, 2010 10:30 AM
> *To:* John Aulbach
> *Cc:* eQUEST Users List
> *Subject:* Re: [Equest-users] Fwd: no heating loads to systems --part II
>
>
>
> Thanks John/Vik- Yes. but when I do put in reheat that is the only way the
> systems are receiving reheat, so my question is why are the heating coils
> not doing the primary heating wherefore in my case file, all of the heating
> is up to either reheat (specified by me) or via baseboards (also specified
> by me.)
>
>
>
> The big question is:  why aren't the heating coils doing the job first, and
> then the excess is to be made up via reheat and/or baseboards.
>
>
>
> I have not specified any input for humidty control (based on the help file
> recommendations--b/c we don't have humidification control in the proposed
> building...
>
>
>
> The DOE2 help file indicates:
> *REHEAT-DELTA-T*
>
> Maximum increase in temperature for supply air passing through the zone (or
> subzone) reheat coils. The value specified here applies to all zones in the
> system. This keyword is required in order to simulate heating the air as
> it passes through the terminal reheat coil. Note that when very little air
> is passed (see MIN-FLOW-RATIO) there may be insufficient reheating.
>
> The highlighted statement is noted, but it still doesn't indicate that this
> input is required *in order to simulate any heating requirement.*  It only
> states it is required to simulate reheat heating requirements.  Why don't
> the heating coils work in my model is my "black & white" question....  all
> in all my space heating energy (with reheat & baseboards) is only 1% of the
> total building energy for a climate in Vancouver, BC...  why is it so low?
>
>
>
> ...if I am just really missing something---please don't hesitate to tell me
> so. ---- I have also specified the hot deck temp coming off the htg coils
> which then gave me some capacity in my heating coils, but unfortunately by
> adding this input  all of my numbers have dropped instead of increased.
>
>
>
> I also looked back into the archives to find an answer to this issue--I
> found two others who were having the same problems I have, but they have
> responded that they never figured out the problem either...
>
>
>
> Pasha
>
>
>
>
>
> On Sat, Mar 6, 2010 at 10:34 PM, John Aulbach <jra_sac at yahoo.com> wrote:
>
> Pasha:
>
>
>
> I believe the short answer to this is that not all VAV zones have reheat.
> Therefore, you need to put reheat in the zones that have it. otherwise, all
> systems would get reheat.
>
>
>
> John Aulbach
>
>
>  ------------------------------
>
> *From:* Pasha Korber-Gonzalez <pasha.pkconsulting at gmail.com>
> *To:* eQUEST Users List <equest-users at lists.onebuilding.org>; Vikram Sami
> <vsami at lasarchitect.com>
> *Sent:* Sat, March 6, 2010 9:30:09 PM
> *Subject:* [Equest-users] Fwd: no heating loads to systems --part II
>
>
>
> Thank you both for looking at this.  I'm a bit dumbfounded that it can't be
> as easy as the fact that I need to specify reheat, since I have indicated
> that it is a VAV with reheat system, but if that is the case then I will
> re-instate the reheat delta t so that I can generate heating energy.   (when
> I had input a reheat delta t of 30 degrees F, I was able to successfully fun
> a simulation, but the heating energy numbers where so high (i.e. 30 kWH/sq
> ft or more) that it just didn't seem like this was the correct input for my
> model.
>
>
>
> I just think that it is a bit weird even for the programming that the only
> way I can get heat out of the heating coil is that I have to enlist reheat
> or baseboards in order for the system to assume that there is a heating
> load.
>
>
>
> I understand the logic of why this works, but I don't understand why it is
> a requirement in DOE to have some or ll of the heating capacity specified
> for it to "autosize" or react to the fact that heating loads need to be
> passed to the systems module only if reheat or baseboards are specified.
>
>
>
> If it is possible for any of the eQuest programmers to comment on this
> input requirement I would like to hear thier feedback.  In the meantime,
> what I am understanding is that it is a requirement to specify supplementary
> heating (i.e reheat or baseboards)  in DOE2 for a VAV reaheat system before
> DOE2 will allow a basic heating coil to assume a heating load...somebody
> please tell me I'm wrong-because this doesn't make sense.
>
>
>
> Pasha
>
> ---------- Forwarded message ----------
> From: *Seun Odukomaiya* <sodukomaiya at laceindy.com>
> Date: Sat, Mar 6, 2010 at 4:59 PM
> Subject: RE: [Equest-users] no heating loads to systems --part II
> To: Pasha Korber-Gonzalez <pasha.pkconsulting at gmail.com>
>
>  Pasha,
>
> I took a look at your model. When employing a VAV-Reheat System as you have
> in your model, you must also specify the reheat Delta-T for the zone heating
> coils attached to the units (see attached screenshot). If this is not done,
> the program assumes that the zones have no reheat, and thus will never put a
> load on your hot water loop. This, in turn, causes the error that you've
> seen. The DOE-2 documentation describes it as follows:
>
>
>
> Maximum increase in temperature for supply air passing through the zone (or
> subzone) reheat coils. The value specified here applies to all zones in the
> system. This keyword is required in order to simulate heating the air as it
> passes through the terminal reheat coil. Note that when very little air is
> passed (see MIN-FLOW-RATIO) there may be insufficient reheating.
>
>
>
> According to your model, the maximum zone entering supply air temperature
> is 105 degrees. I also noticed that your zone minimum entering supply
> temperature is 55 degrees. As such, you need to specify your reheat delta-T
> as 50 degrees (as in the screenshot). This ensures that your zone coils are
> able to raise the 55-degree air from the AHU up to the 105 degrees that you
> have specified. Try that, and your model should run just fine.
>
>
>
> *Seun Odukomaiya, LEED AP  -  **Mechanical Engineer*
>
> L'Acquis Consulting Engineers
>
> 9229 Delegates Row, Suite 550
>
> Indianapolis, Indiana 46240
>
> voice:  (317) 706-2075, ext. 255
>
> fax:     (317) 706-2076
>
> email:  sodukomaiya at laceindy.com
>
> web: www.laceindy.com
>
> P* **Please consider the environment before printing this e-mail.*
>
>
>  ------------------------------
>
> *From:* equest-users-bounces at lists.onebuilding.org [
> equest-users-bounces at lists.onebuilding.org] On Behalf Of Pasha
> Korber-Gonzalez [pasha.pkconsulting at gmail.com]
> *Sent:* Saturday, March 06, 2010 4:26 PM
>
>
> *To:* eQUEST Users List
> *Subject:* [Equest-users] no heating loads to systems --part II
>
>
>
> Hi all,
>
>
>
> okay-I'm back to where I was last time I posted this question:  why are
> there no heating loads being passed to my systems?
>
>
>
> Here's the story: (160,000 sf high school building)
>
>
>
> The attached file is my baseline 90.1 model using System 7 (VAV w/reheat)
>
> As the file is now-I have removed the reheat delt-T (30 deg), and removed
> any baseboard heating in all /systems/zones and removed any input of heating
> capacity of the coils.  With this, my file receives the following error:
>
>
> ***ERROR***********************************************************************
>
> Loop: Hot Water Loop has zero design flow.
>
> Check input for consistency, or specify design loads.
>
> Right now I am trying to have DOE2 'autosize' anything it can so that I can
> get a good run and go back and adjust equipment capacities....but I don't
> know where else I can look further for why the systems aren't receiving the
> design loads.---thus creating the above error.  Something is stopping DOE
> from passing the loads to the systems.  When I open my sim file, the only
> reports being produced are the L-reports.
>
>
>
> If anyone has any hints or can take a look to find what it is I'm
> missing--I know it's a simple thing, but can't seem to find why it is doing
> this.  (I've been staring at these files tooo long...)
>
>
>
> ---on a side note--after all the help I received with this issue earlier
> this week I have input all of the temp schedules that are required, and all
> that I know needs to be input to get the systems to run.  any help would be
> greatly appreciated so I don't have to go back and rebuild this model from
> the beginning....I'm too close to the end to go back and rebuild
> another file.
>
>
>
> Thanks in advance!
>
> Pasha
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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