[Equest-users] SIM report for annual water consumption?
Sharad Kumar
sharadcapricious at gmail.com
Tue Jul 21 23:57:34 PDT 2020
Hi Nick,
I fully abide by your thoughts that how annually the formula has been
deciphered by you.
You have also considered the inlet or makeup water as ground water
temperature.
Also you have tried to configure the annual dT as the temperature
difference between supply and ground water temperature.
But as per me if you are trying to configure the GPM in the DHW loop then
the temperature difference is required to be calculated upon the inlet of
the tank and outlet temperature difference which might can be the discharge
water temperature .If there is open loop then the temperature difference
shall be between the inlet tank temperature and discharge water temperature
.No worries if these temperature are accounted to calculate dT then one
should believe that only tank volume will be considered. After this one
should not consider that only tank volume or dT might be considered while
the loop is also being considered.
Also one should consider that the flow shall be regular everywhere after it
comes from outlet of the tank. Hence GPM shall be same all over
The other factors which were missing in the basic formula were the tank
wall,and pipe wall losses and also the system efficiencies.
With these considerations we can estimate that delta T should be calculated
upon minute or second basis as pe me.
The required Q (BTUh) shall be the tank capacity based and the added loop
volume based total heat added.but to rather configure out we shall consider
only the tank added Q as the heat being added to tank itself.
The thing that we are required to have as the solution is the GPM not the
annual GPM.
GPM should be in minutes and also dT is something which should be as per
minute or seconds.
I think this is the same dT which you are inferring as dT annual.
With these considerations i can infer that I have tried something which can
be like an add-on to my prior mail.
Sorry to others if it seemed to be offended to someone.
*Thanks,*
Sharad.
......................................................................................................................................................
On Wed, Jul 22, 2020 at 8:44 AM Nicholas Caton <Nicholas.Caton at se.com>
wrote:
> Hi Sharad – your contribution provoked me to consider this further (read:
> I have work I’m supposed to be doing and I like indulging in a distraction
> on occasion),
>
>
>
> I’ve spent a little time trying to intuit your recommended shortcut. I
> think I understand it now, but want to explain the estimation method for
> others and to confirm understanding. Perhaps I have missed a more elegant
> shortcut?
>
>
>
> To preface: We should observe the formula Q = 500*GPM*dT can be tricky
> when applied against open loop fluid systems, if all inlet/outlet streams
> aren’t considered. If you focus too narrowly on only supply and return
> (recirc), without accounting for the makeup fluid stream… One might say you
> could end up in hot water ;-).
>
>
>
> We can use this equation to *estimate* consumption (kgal) of domestic hot
> water (DHW) per year, but it will require some assumptions and
> manipulations along the way:
>
> - To first recap: Q = 500*GPM*dT is, without further modification,
> intended to calculate the rate at which heat is imparted/extracted (Btu/h)
> at a given flow rate (gallons per minute) and difference in temperatures
> (dT), for a fluid with thermal properties substantially aligning with plain
> water (the constant 500).
> - Let’s also clarify what we’re trying to solve for: Gallons of DHW
> consumed per year. Provided no leaks in the system and ignoring drains for
> maintenance/repairs, this volume should match the makeup water introduced
> into the DHW system over the same time period.
> - Assuming Makeup water = Groundwater Temps, then
> - Ignoring tank/storage losses, and ignoring losses in distribution
> between makeup water entry and the points of delivery,
> - and further asserting DHW consumption is equalized through the
> year (there is not a lot more DHW consumption in August vs. February),
> - the annualized delta will be *dT,ann = (Supply Water Temp – Mean
> Groundwater Temp)_*
> - eQuest with no special/extra effort generates Btu/year of metered
> fuel/electricity used for DHW heating, as part of the rainbow report
> outputs.
> - This is not directly Q, which represents heat applied to the fluid
> - We need to consider and condense into an annualized figure the
> “system heating efficiency”, considering
> - Combustion efficiency
> - Startup/cycling losses
> - The presence/frequency/degree of condensing operations and
> heat recovery, if applicable
> - This system efficiency may naturally involve many or few
> assumptions depending upon the DHW system type
> - Then the annualized heat addition is *Q,ann (Btu/h) = (Consumed
> Btu/year from Fuel Meter End-Use rainbow report) / (System Heating
> Efficiency) * (1 year / 8760 hours)*
> - Taking these together, we can solve for annualized flow rate,
> GPM,ann:
> - GPM,ann = Q,ann / (500 * dT,ann) = *(Consumed Btu/year from Fuel
> Meter End-Use rainbow report) / (System Heating Efficiency) * (1 year /
> 8760 hours)* / 500 / *(Supply Water Temp – Mean Groundwater Temp)_*
> - And from the annulalized flow rate, we can calculate kGal/year
> - *GPM,ann * (1 kGal / 1000gal) * (525,600 minutes / year) =
> kGal/year*
> - So altogether, we’ve had to make a few assumptions to leverage the
> following shorthand:
> - *kGal/year = (1 kGal / 1000gal) * (525,600 minutes / year) *
> (Consumed Btu/year from Fuel Meter End-Use rainbow report) / (System
> Heating Efficiency) * (1 year / 8760 hours)** / 500 / (Supply Water
> Temp – Mean Groundwater Temp)*
> - Aside: At this juncture you should recognize there’s a qualifier
> that’ll affect a lot of commercial DHW applications. This is kGals/year of
> water *at the given Supply Water Temp**. *If the DHW requires a
> mixing valve at the point of delivery or upstream, to avoid scalding
> hazards, and you want to calculate the gallons leaving all of the faucets
> (at a safer, lower temperature), then you need to factor this result to
> reflect how many gallons of, say, 120F water will be consumed given fewer
> gallons of 140 or 180F generated.
>
>
>
> *TLDR:* I’m not sure this approach, which requires a number of
> assumptions/rounded corners, is much faster than working out the annual
> delta between supply vs return flow on the DHW loop, as originally
> suggested by Phil. That does seem to be the most direct route to
> understanding exactly what was simulated (with some of the same caveats
> from that final bullet around mixing valves). *3 Points for Phil’s
> favorite Hogwarts House!*
>
>
>
> ~Nick
>
>
>
> *Nick Caton, P.E., BEMP*
>
> Senior Energy Engineer
>
> Energy and Sustainability Services
> Energy Performance Contracting
>
> D
> M
> E
>
>
> 913 . 564 . 6361
>
> 785 . 410 . 3317
>
> *nicholas.caton at se.com <nicholas.caton at se.com>*
>
> 15200 Santa Fe Trail Drive
> Suite 204
> Lenexa, KS 66219
>
>
>
>
>
> *From:* Equest-users <equest-users-bounces at lists.onebuilding.org> *On
> Behalf Of *Sharad Kumar via Equest-users
> *Sent:* Sunday, July 19, 2020 2:12 AM
> *To:* equest-users <equest-users at lists.onebuilding.org>
> *Subject:* Re: [Equest-users] SIM report for annual water consumption?
>
>
> ------------------------------
>
>
> Hi Phil, The way that I am thinking about is the option to get the result
> on the basis of eQuest software back calculations. The calculation on
> which DHW outputs are based is the formulae Q= 500X GPM X delta T. Now
> to get the GPM or the actual flow one will have to deter the Q or the total
> heat across the DHW in Btuh. From the heat delta T across the DHW one will
> come to know the delta T across the DHW in degree Fahrenheit. Now from
> the basic formula Q= 500 XGPM X delta T knowing the two factors GPM and
> delta T one can easily determine GPM across the DWH.
> As per my experience the energy simulation software are based on these
> easy back calculations of which one is above here. From this Gallon per
> minute (GPM) or the flow is got ahead. Thanks and Regards, Sharad.Kumar
> Freelancer India
>
>
>
>
> ---------- Forwarded message ----------
> From: Phil Jordan <phil.jordan at clearesult.com>
> To: "equest-users at lists.onebuilding.org" <
> equest-users at lists.onebuilding.org>
> Cc:
> Bcc:
> Date: Wed, 15 Jul 2020 20:43:51 +0000
> Subject: [Equest-users] SIM report for annual water consumption?
>
> Does eQUEST output annual water consumption in the SIM report (for DHW)?
> Or do you have to set up an hourly report to sum the DHW loop “Fluid flow,
> supply side” variable?
>
>
>
> Thanks,
>
>
>
> *Phil Jordan*
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Phil Jordan <phil.jordan at clearesult.com>
> To: "equest-users at lists.onebuilding.org" <
> equest-users at lists.onebuilding.org>
> Cc:
> Bcc:
> Date: Thu, 16 Jul 2020 01:39:55 +0000
> Subject: Re: [Equest-users] SIM report for annual water consumption?
>
> I think the way to do this is to set up an hourly report for both the
> “Fluid flow, supply side” and “Fluid flow, return side” for the DHW loop –
> the difference between the two should be the flow that’s going down the
> drain at each hour; the sum of this would be the annual DHW water
> consumption.
>
>
>
> But if anyone knows of an easier way to get this from the SIM report
> please share.
>
>
>
> Thanks,
>
>
>
> *Phil Jordan*
>
>
>
> *From:* Equest-users <equest-users-bounces at lists.onebuilding.org> *On
> Behalf Of *Phil Jordan via Equest-users
> *Sent:* Wednesday, July 15, 2020 1:44 PM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] SIM report for annual water consumption?
>
>
>
> *EXTERNAL email. Please exercise caution. This e-mail is from a sender
> outside of CLEAResult. Do not click any links or open any attachments from
> unknown senders or unexpected email. *
> ***************************************************
>
> Does eQUEST output annual water consumption in the SIM report (for DHW)?
> Or do you have to set up an hourly report to sum the DHW loop “Fluid flow,
> supply side” variable?
>
>
>
> Thanks,
>
>
>
> *Phil Jordan*
>
>
>
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