Hello all,

I am modeling a building with eQUEST that has a tankless, a.k.a.
instantaneous, gas-fired hot water heater. I am uncertain of how to
baseline the system according to ASHRAE 90.1-2004 Appendix G. The standard
states that for a 180,000 BTU/h system the EF (Energy Factor) = 0.62-0.0019V.
So, I set V equal to zero for the tankless/instantaneous gas water heater
and get an EF =0.62.

The question I have for everyone is: How do I translate this baseline EF to
HIR (Heat-input-ratio) for eQUEST? Is there an accepted method for doing
so? I saw in a previous post from David Eldridge on 3/21/07 that
calculating HIR = 1/EF leads to unreasonably high values for HIR (In my
example, 1/0.62 = 1.61), but I'm having trouble seeing how else to come up
with a baseline.

Thanks in advance for your help.

Best,

Andrew McNamara, LEED AP