Hot water line size

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Keydash

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Uncertain about what size of hot water line to use.

Small structure: 1 shower, lav, toilet, washer, kit sink.

The cold water line is 3/4 pex reducing to 1/2 at the bibs, then to 3/8 at fixtures other than the washer. I will be using an on demand water heater connected to the pex through a length of iron pipe.

Question: Should I follow the same sizing for the hot water line as laid out for the cold water line or just run 1/2 pex for the hot throughout? The water heater has a 3/4 inlet and outlet.
 

Jimbo

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Conventional wisdom says 3/4 copper ( 1" PEX) for the mains, reducing to 1/2" copper ( 3/4" PEX) for individual fixtures. These days, for low flow fixtures like lav faucets and showers, the smaller pipes have advantages. But for hi-demand fixtures like a tub or washing machine, you would quickly regret smaller pipes.

pipe_size_1.jpg



pipe_size_2.jpg
 
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