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#1187 Altered DHW Using Wrong Standard Design
Done
None
Critical
Comp.Error
2019
Unaffected
CBECCr
2021-02-11
2020-01-11
No
Altered DHW is using EF for the standard design and UEF for the proposed design, so get a penalty for a minimum effiiency replacement. Related to Ticket #1052.
Discussion
It is also not allowing alterations to be electric, or HPWH.
Need clarification of problem here -
Original EAA model "AlterDHW" (from ver 2019.1.1) includes Altered DHW - Gas Instantaneous w/ 0.81 UEF and the standard design is modeled w/ a Gas Inst having 0.82 UEF.
Second EAA model "Alter DHW" (from ver 19.2.0 (1126)) includes Altered DHW - heater is Elec Resistance Consumer Storage (0.92 UEF) and is replaced in the std design w/ our normal std design NEEA HPWH ("Std UEF2 NEEA HPWH").
Not sure what is meant in original ticket description by "using mismatched WH calculations" and not finding what is described in comment above "not allowing alterations to be electric".
Comply with Section 150.2(b)1H which allows an electric storage (if no gas available) or gas storage replacement. The standard design should be the current minimum UEF required. Nothing is compared to EF. Not sure how to deal with "verified existing efficiency." May need to come up with a general rule rather than using the old DHW calculations (e.g., if the old water heater was a 0.525 EF, use 0.52 UEF).
Danny suggted (via email, so I'm posting here) for verified existing DHW: The issue is that the existing water heater is using EF and the old calculation method. My suggestion is to take the EF input and convert it to UEF behind the scene. We should be able to do this relatively easily. This is the inverse of what we did for 2016, when we convert UEF input to EF internally.
Diff:
Posting table sent via email showing correct standard design for new, altered DHW.
partial fix for this ticket committed to SVN @ r1904
fixes problem where Altered DHW heaters of type Small Inst or Consumer Inst were being modeled in Standard design as (non-UEF) Small Inst rather than (UEF) Consumer Inst (as they are for New heaters)
additional mods for this ticket committed to SVN @ r1932
fixes for analysis of Altered (gas & elec resistance) Consumer Storage DHW systems now included
further work on this ticket continued in ticket #1265