Replacing water heater with instant on demand hearer

[freddmc]

I am looking at replacing our natural gas fired 40 gallon hot water tank with a gas fired on demand water heater. This will be a whole house heater. How do I determine that I have enough throughput for my house?
Regards
Fred

 

[Twowaxhack]

Get a 199,000 BTU unit.

 

[breplum]

199k is the largest they make for residential. If you get a 96% efficient condensing (recommended) that's as good as it will get.

 

[Mitchell-DIY-Guy]

The Feds have determined that anything 200,000 or larger (hence the 199,900) is a BOILER not a heater. Whole separate sets of rules apply.

Get the 199 model.

You’ll probably need gas line work, maybe a meter change too. That’s 5x the gas consumption of a tank style water heater.

 

[CT-18]

You may want to check incoming water temp and what flow you get at what heat rise. A lot of them brag about their GPM but what is that heat rise at that GPM

 

[havasu]

Get a 199,000 BTU unit.

The Feds have determined that anything 200,000 or larger (hence the 199,900) is a BOILER not a heater. Whole separate sets of rules apply.

Get the 199 model.

You’ll probably need gas line work, maybe a meter change too. That’s 5x the gas consumption of a tank style water heater.

199k is the largest they make for residential. If you get a 96% efficient condensing (recommended) that's as good as it will get.

i never knew the reason for this. Thank you for explaining it.