[Equest-users] How intermittent fan operation works

[Mayank Bhatnagar]

Thank you Maria for the modelling guidance.


On Fri, Apr 5, 2019 at 7:10 PM Maria Karpman <
maria.karpman at karpmanconsulting.net> wrote:

> Mayank,
>
>
>
> The attached NYSERDA tech tip describes how to model several common
> multifamily ventilation strategies in eQUEST. It’s based on 90.1 2010 App G
> and eQUEST v3.65 build 7173 (pre-VRF/DOAS version) so may require some
> adjustments if you use the latest version. See also EPA Energy Star
> Multifamily Highrise Program Guidelines
> <https://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/mfhr/ENERGY_STAR_MFHR_Simulation_Guidelines_AppG2016.pdf?56fa-56ac>
>  Examples 6-9 & 6-10 and Sections 6.5.12.1 (a) & 6.5.12.3(c).
>
>
>
> Maria
>
>
>
> *From:* Equest-users <equest-users-bounces at lists.onebuilding.org> *On
> Behalf Of *Mayank Bhatnagar via Equest-users
> *Sent:* Friday, April 05, 2019 8:39 AM
> *To:* Nathan Miller <nathanm at rushingco.com>
> *Cc:* equest-users at onebuilding.org
> *Subject:* Re: [Equest-users] How intermittent fan operation works
>
>
>
> Dear Nathan,
>
>
>
> Thank you for quick response.
>
>
>
> The project is a residential building and the ventilation is through the
> system. To meet the ventilation requirement with *intermittent* operation
> mentioned in *ASHRAE 62.2-2010,* the system need to run atleast 30
> minutes in each hour. From this the question is come for sub-hourly
> operation.
>
>
>
> I am thinking of an approximation which I want to put for expert opinion:
>
> A PVVT system can be modelled with minimum air flow ratio to 50% with
> continuous fan to approximate cycling and minimum operation time for
> ventilation.  The reduction of low speed based on cooling/ heating load can
> be similar to intermittent operation where the system is running for
> fractions of an hour (similar pattern as in intermittent operation in my
> earlier mail).
>
>
>
> Please let me know your thoughts and/ or other work around.
>
>
>
> Thank you.
>
>
>
> Regards,
>
> Mayank Bhatnagar
>
> On Thu, Apr 4, 2019, 7:29 PM Nathan Miller <nathanm at rushingco.com> wrote:
>
> Assuming you have another system/method responsible for providing
> ventilation  to the units, I’d model it more or less the way you have, but
> I’m not clear from your description that you have all the settings correct
> for a cycle-on-demand system. In the climate zones I usually model in there
> would be hours where the fan does not run at all, but that’s obviously
> highly depending on T-stat settins and ambient conditions.
>
>
>
>    1. Coolin fan schedule should be something that is all-zeros (meaning
>    the system never HAS to run). This essentially means the unit thinks it is
>    in “night/unoccupied” mode all the time.
>    2. Select Cycling fan control, and intermittent operation (looks like
>    you did that)
>    3. Night Cycle Control should be “Cycle On Any”. Since you already
>    told the system it is ALWAYS in night-mode (meaning it’s not forced to
>    run), then fan will remain off until temps in the space drift out of
>    dead-band mode, and then system will turn on fans and condition the space
>    until temps are satisfied, and then shut off agin. With settings above,
>    partial hour fan operation is allowed.
>
>
>
> You said you want to know if you can “create schedule to restrict cycle
> off on sub-hourly”. I’m not clear what you mean. If you want the fan to be
> prevented from only running for partial hour you can use Continuous instead
> of Intermittent Indoor Fan Mode.
>
>
>
> *Nathan Miller, PE, LEED AP BD+C** – **Mechanical Engineer/Senior Energy
> Analyst*
>
> *RUSHING* | *O* 206-285-7100 | *C* 207-650-3942
>
> *www.rushingco.com <http://www.rushingco.com/>*
>
>
>
> *From:* Equest-users <equest-users-bounces at lists.onebuilding.org> *On
> Behalf Of *Mayank Bhatnagar via Equest-users
> *Sent:* Thursday, April 4, 2019 9:31 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] How intermittent fan operation works
>
>
>
> Dear all,
>
>
>
> I am working on a residential project in which the indoor units fan is
> cycling with load. For this, I have modelled as PSZ HP (as designed) and
> changed indoor fan mode from continuous to intermittent operation. My first
> question is whether it is correct to model intermittent for system with
> cycling or should I model different system.
>
>
>
> Additionally, as per definition of intermittent operation : The indoor fan
> operates as in CONTINUOUS, but only for  that fraction of the hour required
> for space heating or cooling. I want to check how many hours it is cycling
> as I assumed that the eQUEST is working on hourly timestep. By extracting
> hourly report of fan cycle ON for continuous and intermittent operation,
> the hourly profiles are:
>
> From the figure, it appears that fan is running maximum 60% of an hour in
> intermittent operation whereas 100% in continuous. As it is providing
> results in sub-hourly basis, is it possible to create schedule to restrict
> cycle off on sub-hourly?
>
>
>
> Thank you.
>
>
>
> Regards,
>
> Mayank Bhatnagar
>
>
>
>
>
>
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