Turn on demand gas hot water heater to 140 degrees
 

and got nice 120 degree water at the shower, all the way on hot!

much nicer in the morning

We set ours at 135 and it's decent enough. Almost no wait time. The default of 120 degrees is nuts. Would have to wait 5 minutes to shower.

Always start shower with super cold water, by the time warm water comes, I am done. Warm to hot water doesn’t do any favors to skin.

I increased the max water temperature, as others have done, because I wanted hotter water.

I have not noticed that having any effect on wait time however. Some people have said their wait time is shorter. I wonder why that would be. It should be set by the water pressure and the along-the-pipe distance from the heater to the shower head.

Is it just psychological or is the hot water wait time actually reduced if you increase the hot water temperature.

Might depend on how well the pipe is insulated - with hotter water heating up the pipe more quickly whereas cooler water would continue to lose heat to the pipe for longer

I actually compared mine when I bumped it from 120 to 135 based on the advice of a retired plumber that lives on my street. I was skeptical, so I wanted numbers to validate that it actually did anything.

I don't remember the exact numbers but it was around 60 seconds to warm up previously on an average day. Now it's closer to 30 seconds to hit maximum heat. This is for my master bedroom shower which is at the opposite end of the house from the on demand water heater.

I can get it to heat up even faster if I run the master bathroom hot taps at the same time.

I'm pretty sure that if you set them higher than 120 you void your warranty so if your heater is still under warranty, be careful. There's a reason they don't advise anything hotter than 120. I found that by turning on the shower before getting undressed it is fully hot by the time I get in it.

From my waranty:

Damages, malfunctions or failures caused by operating the unit at water temperatures exceeding the maximum setting of the operating, or high limit, control.

I would rather void my warranty and pay $900 for a new unit at an undetermined point in the future than deal with spending an extra minute standing around half naked everyday to avoid a cold shower for the rest of my life.

I would just set it back to 120 if anything happened anyways.

I'm reading this and you do understand that the temperature of the water differs on the preference of the person and if it's an issue of wait time turn the water on and brush your teeth.

Got ours set at 130. Makes a big difference

Thanks for this tip!

just wondering the exact same thing!

by laws of physics, the wait time would be longer with a lower temperature, due the heat loss in the foundation heat sink, think relative temperature for foundation absorption

Watching homes being built near us, I never seen any of them put insulation on the hot water pipes. I guess that would cost them some of their profit.