[Equest-users] ASHRAE baseline EIR for service hot water heater in eQUEST

Thu Dec 6 00:17:57 PST 2018

Thanks for your response.

As per ASHRAE 90.1 : 2010 appendix G electric resistant based water heater to be model and sized according to section 7.4.1.
In base case and efficiency of electric heater should be considered as per table 7.4.2.
In my project the capacity of heat pump based SWH is as follows:

  1.  Rated heating capacity : 19.8kW
  2.  Rated power input : 6.02 kW
  3.  Maximum power input : 6.8kW

As per table 7.8 performance required for resistance based electric should be 0.93-0.00132 V EF, which is again 0.233 EF.
In modeling tool eQUEST, EIR is required which is ratio of electric input power to nominal heater capacity.
EF is a combination of thermal efficiency and standby losses, in case if i modeled tank losses as 0 by putting Tank UA =0 in DWH in eQUEST. What should i model in EIR?

Please someone guide can guide on this.

Warm Regards
Harshal Gupta
Energy Analyst
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________________________________
From: David Eldridge <DEldridge at grummanbutkus.com>
Sent: 05 December 2018 01:10
To: Harshal Gupta
Subject: RE: ASHRAE baseline EF for service hot water heater

I don’t want to post to the list since this isn’t my main expertise. But EF includes the value of the insulation of the tank as well as cycling losses, so 1/EF can’t be the COP exactly, since it includes tank losses it won’t be the reciprocal of compressor efficiency.

You would be modeling the losses explicitly in the modeling program, correct? So you just want the actual heat pump system COP.

I think EF is proportional to COP though, not inverse – i.e. higher EF is better and higher COP is also better. Gas storage systems have EF less than one, and sometimes much less than one…a heat pump could be above 1.0, but I don’t have a great feel for it – my expectation might be more in the 2.0 range than 4.0 but that’s a gut feeling.

https://www.energy.gov/energysaver/estimating-costs-and-efficiency-storage-demand-and-heat-pump-water-heaters

Not sure about the pump – if the recirculation is the same in both cases, model it identically. I don’t believe it is meant to be built into the EF, and I also don’t know of any other W/gpm requirement for them…check the rest of the service hot water section for any pump power requirements that I might be forgetting.

David

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

Grumman/Butkus Associates

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Harshal Gupta via Equest-users
Sent: Tuesday, December 04, 2018 2:24 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] ASHRAE baseline EF for service hot water heater

Hello All,

Project Details

I have an issue for conversion of EF to COP of service hot water heater.

Their is a service hot water heater installed in my project of 2000 L or 528 US gallons capacity. Heater is equipped with a re circulation pump of 4kW.

Modeling Issue

As per ASHRAE 90.1 base case the minimum efficiency to be considered in base case as per table 7.8. Minimum efficiency  formula as per table is 0.93-.00132 √V EF.

With the above formula considering V as 528 US gallons Energy Factor (EF) will be 0.233. In many articles it was marked COP is 1/EF, by this statement COP will be 4.299.

This is giving me the negative savings.

Can any one help me with correct process for conversion of EF to COP.

Secondly, what should be pump power in base case?

Thanks in Advance

[cid:image001.png at 01D48BC7.92B8BBC0]

Warm Regards

Harshal Gupta

Energy Analyst

 LEED AP<https://www.usgbc.org/organizations/environmental-design-solutions-eds?view=employees> || IGBC AP<https://igbc.in/igbc/redirectHtml.htm?redVal=showIgbcApnosign> <http://www.grihaindia.org/index.php?option=com_fabrik&view=list&listid=31&t=griha_community&Itemid=0&resetfilters=0> || GRIHA CP<http://www.grihaindia.org/index.php?option=com_fabrik&view=list&listid=31&t=griha_community&Itemid=0&resetfilters=0>

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