Instantaneous gas water heater with small tank to meet PHIUS+ hot water performance requirement
We are well into the construction now, and don’t have a lot of flexibility. For example, have 3” venting pipes in place for what was meant to be Eternal condensing hybrid gas hot water heater with 2 gallon tank. The small tank helped to reach PHIUS+ requirements of not wasting more than 0.6 gallon of water before the water temperature at the furthers fixture reaches 75F. (We also designed very small diameter hot water pipes to help that goal). Alas, the company making Eternal went out of business and we are in search for a replacement that might have similar characteristics to Eternal GU195 unit. Online search reveals several products, but we’d also like some PHIUS+ experts opinion, if possible.
Other options (don’t seem to have a buffer tank and have a minimum flow
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