Additional water heater elements

[shorowit]

Adds SealedCombustion, CondensingSystem, AtmosphericBurner, and PowerBurner elements for water heaters; these elements already exist for furnaces/boilers.

[shorowit]

@jmaguire1 Can you look these over and provide feedback? I'm not sure if we should use, e.g., "DirectVent" or "PowerVent" instead.

[jmaguire1]

Yes, I never heard from anyone at GTI on this. It is a little confusing, but I think the way we'll want to do this:

CondensingSystem: If a tank WH, TRUE if UEF > 0.77 (or corresponding EF). If tankless, TRUE if EF (or UEF) > 0.94. Else False.

AtmosphericBurner: If tank WH, UEF < 0.64. FALSE for any tankless.
PowerBurner: The opposite of AtmosphericBurner, so TRUE if UEF >= 0.64 and for any tankless.
SealedCombustion: Same as "PowerBurner"

to rewrite the code for skinlossfrac here, I think this makes it:

if "AtmosphericBurner":
skinlossfrac = 0.63
if "Condensing":
skinlossfrac = 0.96
else:
skinlossfrac = 0.91.

What really matters here for whether you fall in the 0.91 category is if there's a flue damper, which I think is true pretty much any time "AtmosphericBurner" is false. Condensing vent a little colder, which is how we ended up with a slightly higher skinlossfrac here.

[shorowit]

Two HPXML WG members lean towards switching to "vented" terminology.

[shorowit]

A good resource from AO Smith: https://www.hotwater.com/info-center/water-heater-venting.html