Choosing the most efficient natural gas water heater
This project involves abandoning a chimney and replacing a natural gas water heater.
We were going to go solar (with condensing direct vent back up), but after realizing how efficient the new generation water heaters are, the savings of going solar are quite small, the payback after incentives AND self install still around 20 years.
Our decision is to just get the most efficient, durable water heater out there and forgo the added expense of solar thermal. We currently have a conventional 50-gallon 40,000-BTU model with an 89 FHR. Our family of six has been well served by the capacity of this water heater. We currently have no space-heating requirements for the water heater.
I’m having a hard time finding a 95% or better efficient water heater in this size and capacity. The best units (listed below) seem to be much larger and often designed for space heating as well. We are not adverse to spending $2,000 to $4,000, as long as there is real value.
We will be adding a 200 sq. ft. room addition in the next couple of years. Its long side faces due south and passive solar heating opportunities abound. Maybe one of these larger water heaters with side-mounted taps would be wise for a radiant slab in the future addition? Is it wise to put radiant in a solar thermal mass? I have seen it done before, locally, but never experienced it.
I have narrowed it down to:
A.O. Smith Next Hybrid (http://www.hotwater.com/lit/spec/res_gas/AOSYG45000.pdf)
A.O. Smith Vertex (http://www.hotwater.com/products/residential/rg-vertex100.html)
Bradford-Whites Residential Ultra High Efficiency Energy Saver Gas Water Heater (http://www.bradfordwhite.com/products2.asp?id=1&product_id=345).
Does anyone have experience with these units, recommendations of others, or a different strategy to offer?
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