Hot Water?

[Rustic23]

I have said in another thread that one thing I won't give up in retirement is long hot showers. Well we had to put in a new H20 heater today, and it got me thinking. The setting, recommended, i 120 degrees, although there are settings up to 160 degrees. Now, scalding factor aside, which is more frugal, to set the heater at 120 and use more hot water mixed with cold to get the desired temp. or say 140 and use less hot mixed with the cold. While this gives you a longer shower, which cost more in the recovery? Assumption would be both showers are of the same length and the shower temp. is the same. It may be that there are two many variables to say. Hey, it's better than arguing politics!

 

[samclem]

Now, scalding factor aside, which is more frugal, to set the heater at 120 and use more hot water mixed with cold to get the desired temp. or say 140 and use less hot mixed with the cold.

The cooler you set the water heater, the lower your bill will be. The fact that you can mix less of the 140 deg F water with more cold water to reach your desired 120 deg F shower temp doesn't make up for the losses. If you use 20 gallons of 120 deg F water in your shower, in a strict theoretical physics sense it would cost you the same to heat it all from ambient to 120 deg or to heat 10 gallons to 170 deg and mix it with 10 gallons of "cold" water at 70 deg F.

But, in the real world it does matter.
1) That hotter water loses more energy sitting in the tank for the 23 hours per day you aren't using it.
2) The heat exchange from the gas burner or the electric element to the water is more efficient the cooler the water is.

So, set the water heater for as cool as you can if you want to save energy. Remember that many dishwashers need incoming water of at least 140 deg F.

 

[quietman]

If you really like long showers, maybe you missed an opportunity to replace your tank water heater with a continuous on demand model.

 

[brewer12345]

I can tell you from my homebrewing endeavor where I have to heat and maintain 10+ gallons of liquid to 150+F temps with an inefficient propane burner with ambient air temps sometimes approaching 32F that sam is right on the money.

 

[calmloki]

In a nod to my childhood and the joy of unlimited hot water "hotel showers" I have our water heater set at a not-child-safe dish sanitizing screaming heat level. Result is that the the mixed hot/cold shower can last a long, long time before I run out of nice us-ably hot water.

 

[LOL!]

Our 2 gas water heaters are in the attic, so setting at 120 and using lots of hot water is clearly more frugal: (1) Heat is removed from the attic which helps keep the house cooler, so A/C usage is reduced and (2) the hot air in the attic reduces the need for gas to heat/maintain the water temp. Sort of.

 

[samclem]

Our 2 gas water heaters are in the attic. . .

Sounds like a setup for a soggy ceiling. I guess if you've got good drip pans and they have drain limes that are clear, that would minimize the risk.

 

[LOL!]

The heaters are "to code" with cleared drip pans. One problem is that during thunderstorms lightning seems to find the water heaters in our area and start house fires.

 

[Rustic23]

I would have put in a continuous flow except this heater was under warranty and the new one was 'free' minus installation.

 

[Nords]

I have said in another thread that one thing I won't give up in retirement is long hot showers. Well we had to put in a new H20 heater today, and it got me thinking. The setting, recommended, i 120 degrees, although there are settings up to 160 degrees. Now, scalding factor aside, which is more frugal, to set the heater at 120 and use more hot water mixed with cold to get the desired temp. or say 140 and use less hot mixed with the cold. While this gives you a longer shower, which cost more in the recovery? Assumption would be both showers are of the same length and the shower temp. is the same. It may be that there are two many variables to say.

I know how you feel; I abandoned Navy shower cubicles when I retired. I don't feel claustrophobic on a submarine but I hate taking a shower when washing your hair means that both elbows are banging into the walls at the same time.

Another factor around here is that water corrosion rates accelerate significantly at temps above 150 degrees. So not only does it cost more to keep the water on hotter standby, so to speak, it shortens the life of the heater.

Dishwasher heaters usually try to maintain temps above 130 degrees, so that's another complicating factor dependent on how often it's run.

Our 2 gas water heaters are in the attic, so setting at 120 and using lots of hot water is clearly more frugal: (1) Heat is removed from the attic which helps keep the house cooler, so A/C usage is reduced and (2) the hot air in the attic reduces the need for gas to heat/maintain the water temp. Sort of.

We have far more hot water than we can use. In July-October the 80-gallon heater reaches its 150-degree limit by 1-2 PM and the roof collectors just bake away at 170-180 degrees for the rest of the day. If only there was some way to recover the extra BTUs...

But our dishes are scaldingly clean.

 

[Texas Proud]

Food for thought.... tankless.... I had one at my old house and I could shower all day long if I wanted.. nice hot water..

Downside... if you liked luke warm showers you were out of luck... you had to have enough flow to get the hot water going, which meant it was not luke warm... so turn it to hotter... start getting hot water... turn it down and use up the hot water you have in the pipe... turn the hot back on as you step aside from the cold water coming out... etc... since I liked HOT, it was not a problem for me...


Another problem I have seen is that my dishwasher wanted hot water... and it did not seem to draw it at a fast enough rate to turn it on.. and when it did... the heater was so far away, the dishwasher was full of water (cold)... had to run the hot water at the sink and then turn on the dishwasher... this was a problem no matter which system used....