HPWH adjustment for confined space

[shorowit]

See RESNET Addendum

[jmaguire1]

@shorowit: We definitely need a field in HPXML for room volume, but do we also want anything related to whether there's balanced ducting or the net free area to an adjacent conditioned space? Because the addendum footnote has a few other criteria where this adjustment doesn't apply rather than just the space volume, I worry if we don't have explicit fields for the other exceptions a rater might just put in the volume even when the other conditions apply and we'd unfairly apply this derate to HPWH efficiency.

Here's the latest language I've seen for this footnote:

[shorowit]

@jmaguire1 I agree with the concern. Seems like we should add two inputs. One could be a boolean like HPWHInstalledProperly or HPWHInstalledAccordingtoManufacturer or similar. Only when false does the volume input get used to derate. And document what the input means in general terms (e.g., these are the general scenarios when a HPWH is considered installed properly), list the equation, and reference the RESNET addendum.

There would have to be a bit of validation/error-checking too. What if they provide HPWHInstalledProperly=false but no volume? What if they provide a volume but don't provide HPWHInstalledProperly?