[Equest-users] PIU system central heat coil ouput
David Reddy
david at 360-analytics.com
Mon Oct 26 16:00:54 PDT 2015
Russell,
This issue was also posted to Unmet Hours, and Matt L. posted what I
thought was a viable workaround, though I never took the time to go back
and check.
https://unmethours.com/question/626/extraneuous-piu-system-central-heat-coil-output/
-David
On 10/26/2015 2:14 PM, Knudson, Russell wrote:
>
> Follow-up thought:
>
> I am just going to ignore the hourly report column “Total central heat
> coil output (Btu/hr)” – not sure how that data is actually used. I
> made a dummy model with no SYSTEM/ZONE heating coils, no baseboards,
> no heating source at all. The “Total central heat…” hourly report
> column sums to a substantial heating load, but the summary energy
> consumption reports show zero energy spent on space heating, just as
> one would expect with no heating coils in the building.
>
> *Russell Knudson **EIT*
>
> desk:404.946.2158 | *HEERY*
>
> *From:* Knudson, Russell
> *Sent:* Monday, October 26, 2015 5:05 PM
> *To:* 'equest-users at lists.onebuilding.org'
> <equest-users at lists.onebuilding.org>
> *Subject:* [Equest-users] PIU system central heat coil ouput
>
> All,
> I see similar behavior. Without a heating coil installed, I see heat coil outputs sporadic and interspersed between hours with cooling coil outputs, but never for two or more hours in a row. Taking the before coil and after coil air temperatures, I can confirm that the heat rate values jive. The best I can figure, in the intermittent hours where cooling is not needed (DX in my case), the return air temp is warming the air within the SYSTEM. Feeling shaky on that theory though. Thoughts?
>
> *Russell Knudson **EIT*
>
> desk:404.946.2158 | *HEERY*
>
> Hi Erik,
> Yes, I should have mentioned that I tried that too. That is typically
> what I do, but I thought perhaps defining a heat source with a small
> amount of capacity would be a reasonable way to alleviate the "free"
> heat energy I appear to be getting...
> Attached is a quick and dirty wizard model that illustrates the issue
> (you will need to download .bin file or change to something
> comparable). This is representative of the configuration I was going
> for except air-cooled DX.
> David
> On 10/17/2014 2:00 PM, Erik Kolderup wrote:
> >/David,/
> >//
> >/Have you tried setting the HEAT-SET-T (Hot Deck Max Leaving Temp) to /
> >/no value (i.e. Restore Default)? I think that any value for that /
> >/keyword enables heating at the AHU level./
> >//
> >/-Erik/
> >//
> >/*Erik Kolderup, PE, LEED AP*/
> >/erik at kolderupconsulting.com
> <http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org>
> <mailto:erik at kolderupconsulting.com
> <http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org>>|
> /
> >/415.531.5198 | www.kolderupconsulting.com
> <http://www.kolderupconsulting.com> /
> >/<http://www.kolderupconsulting.com>/
> >//
> >/On Fri, Oct 17, 2014 at 1:29 PM, David Reddy <david at
> 360-analytics.com
> <http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org> /
> >/<mailto:david at 360-analytics.com
> <http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org>>>
> wrote:/
> >//
> >/ Hi all,/
> >/ I am modeling a PIU system w/ a water-cooled DX coil and series/
> >/ electric FPBs; no central or preheat heating coils. Using eQ v3.64/
> >//
> >/ SV-A report indicates heating capacity for system is 0./
> >//
> >/ Despite this configuration, hourly reports of for SYSTEM, 'Total/
> >/ central heat coil output (Btu/hr)' indicates there is varying/
> >/ amount of central heat energy output in the first 1-2 and in some/
> >/ cases, the last 2-3 hours of many days in heating months (location/
> >/ Seattle, WA). This is also confirmed by looking at the difference/
> >/ in energy reported between SS-A Heating and SS-B Zone Heating. It/
> >/ is not necessarily a trivial amount of energy, ~25% of total./
> >//
> >/ Have others observed this before, and if so, found a way to fix
> this?/
> >//
> >/ Can't say I've tried everything I can think of, but this is what I/
> >/ have tried:/
> >//
> >/ A) Set HEAT-SOURCE = "ELECTRIC" and use a very small capacity both/
> >/ -1 or -1000/
> >/ B) A + setting HEAT-CONTROL = "CONSTANT"/
> >/ C) B + set HEAT-SET-T various values, including minimum (50F)/
> >/ D) Setting HEATING-SCHEDULE to something that locks out heating. /
> >/ This works, but also locks out zone heating, so not a viable
> solution/
> >//
> >/ Thanks in advance for any input./
> >/ -David/
> >//
> >//
> >/ -- /
> >//
> >/ David Reddy/
> >//
> >/ *360 Analytics*/
> >/ Building Energy Analysis Consultants/
> >/ mail: 9750 3rd Ave NE, Suite 405, Seattle, WA 98115/
> >/ office: 206.557.4732 x 201 <tel:206.557.4732%20x%20201>/
> >/ cell: 206.406.9856 <tel:206.406.9856>/
> >/ web: www.360-Analytics.com <http://www.360-Analytics.com>
> <http://www.360-Analytics.com>/
> >//
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