Water heater supply line smaller than return?

[Deathtofishy]

Couldn't find a post related to my question when searching, sorry if this has been answered.

I have a newer water heater in one of my rental units (installed by previous owner), and I am replacing all the old galvanized steel pipes in the basement with PEX due to corrosion and poor flow.

The 18" copper water heater adapters are both 3/4", but the supply line going to the water heater adapter is 1/2" and the return is 3/4".

The old galvanized was setup this way, so not sure if whoever installed it just followed what was there before, or if there is a reason for the smaller supply?

Never seen this before on the couple hot water heaters I've had to mess with in prior homes.

Can't imagine any negative switching to a 3/4" supply, maybe also even help with volume in the entire hot side?

 

[Reach4]

Can't imagine any negative switching to a 3/4" supply, maybe also even help with volume in the entire hot side?

Increase to 3/4 up until you split to supply hot to only one kitchen or one bathroom.

More volume (gallons) in the hot piping is a downside of bigger pipe (longer to wait for hot) but more flow rate (gpm) is good for the hot pipe to avoid pressure drops when the pipe supplies a bunch of stuff.

 

[Sponsor]

 

[Deathtofishy]

Reach4,

Maybe my terminology in the first post wasn't clear.

The tee off the cold supply to the hot water heater is downsized to 1/2". That is what I am wondering if I should increase to 3/4"

The hot line coming out (what I referred to as return), is 3/4" until it splits to each of the individual fixture (faucets/bath/laundry), where it goes down to 1/2". Which I know to be normal/correct.

 

[Terry]

The water heater should be supplied with 3/4"
1/2 only works for two fixtures at a time. You should have 3/4" going in and out, and then break it down to 1/2 to the kitchen, the bathroom, the second bathroom, the washer.
These all get their own 1/2" lines off the 3/4".

 

[Reach4]

The tee off the cold supply to the hot water heater is downsized to 1/2". That is what I am wondering if I should increase to 3/4"

Cold path to the WH should be 3/4 at least.

Hot path out of the WH should be 3/4 until you tee off to where 1/2 is appropriate.

 

[Deathtofishy]

Perfect. Exactly what I was assuming.

Thanks Reach4 and Terry for the confirmation.

 

[Master Plumber Mark]

Actually we see a lot of older homes in our town piped totally with 1/2 galvanized pipe
reducing off the meter from 3/4 down to the 1/2....you got to work with whateve you have
been handed... In most cases it will be negligible


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