Junkdrawer Dog
Well-known member
I think it's a matter of competing interests. 120 maximum to prevent scalding. 140 minimum to prevent bacterial growth. I trust myself to adjust the temperature of my shower.
What temperature do you set your hot water to?
- Thread starter JackOfDiamonds
- Start date
Hobby_Man22
Well-known member
I think the shower faucet limits it to 120, so it doesn't matter how hot the water heater is.
Junkdrawer Dog
Well-known member
What about faucets?
Hobby_Man22
Well-known member
Probably the same thing. You can adjust them of course though.
Junkdrawer Dog
Well-known member
IDK? The photo is a page from my water heater manual. Perhaps the use of temperature limiting mixing valves is not guaranteed to be 100% universal?
Viper98912
Well-known member
165!!! Whoa!!!
I also read that at about 140 you can start to get severe burns if the amount of water is significant. This is why many shower valves have a plastic feature that helps you limit how far you can turn the handle. But you're right, I don't think it exists for most sink faucets. And, this is critical if you have children at home.
We keep ours at 120, but it's tankless, and it's plenty hot (I don't go all the way to the end on our faucets). If you are needing more tank volume (and you're inherently using a hotter temp to combat less volume), then you may need a new tank (that isn't full of scale inside) or a larger tank. And ideally, you should go tankless if you have a large enough gas line, as that allows you to keep a "normal" temp and have a limitless amount of hot water.
I also read that at about 140 you can start to get severe burns if the amount of water is significant. This is why many shower valves have a plastic feature that helps you limit how far you can turn the handle. But you're right, I don't think it exists for most sink faucets. And, this is critical if you have children at home.
We keep ours at 120, but it's tankless, and it's plenty hot (I don't go all the way to the end on our faucets). If you are needing more tank volume (and you're inherently using a hotter temp to combat less volume), then you may need a new tank (that isn't full of scale inside) or a larger tank. And ideally, you should go tankless if you have a large enough gas line, as that allows you to keep a "normal" temp and have a limitless amount of hot water.
Buy two 40's and hook them together.
I remember being in California and going to get a glass of water all confused why the cold was almost hot. My first thought was someone goofed the plumbing and not that "cold" isn't ice cold glacier water like im used to.Ours will be off the rest of the summer. It's hot here in Phoenix and our water lines run through the attic.
Could take a shower with just a hint of actual hot water, where here it's the other way.
Yeah, common 60-70 years ago.
We were 5 growing up, 50 gallon tank. Never ran out of hot water that I can remember.
Tchicken
Well-known member
+1 Same 5 of us but we had 40 gallons and the third shower was best taken quickly. Times have changed but I still do with a 40 as nothing bigger will fit in the utility closet. Looked at tankless the last time but too pricey for an old coot so I accept the Legionnaires Challenge
I can't remember ever 5 people taking showers one after another. Only 1 bathroom anyhow. But still would be only pulling hot water for maybe 35-40 mins total.
Get in, get washed, get out. No reason to be in there for 20+ mins staring at the wall like a horse unless you're half immobile ir weight 700lbs and have a battleship worth of skin to wash
larry4406
Well-known member
I think this is Federal law.
jar944
Well-known member
140 at the kitchen sink.
Beerhippie
Well-known member
It's not just MD. For our pub, I daisy-chained (series) two 40s to get enough water for the kitchen and pub bathroom.
Good call on the tempering valve.
Galvy pipe was the most common in use years ago. Not sure about code these days (my last IPC book is from the '90s). If you have any copper pipe installed, the galvy is probably pretty well rusted out.
FWIW, I set the pub heaters to 140F and use a tempering valve. The brewery heater--1,200 gallons, heated by three Rinnai C199 tankless heater recirculating (they really aren't made for this)--I set to 185F. Gotta be careful with that water, but we mash in at 176F.
bwringer
Well-known member
That's what I was wondering, too. Well, which is it?
I knew someone who contracted Legionnaire's, probably at a hotel, and it durn near killed him. It's no joke at all.
Still, 165 is nucking futs.
Ours is currently set to 135 for a bit more efficiency and life; the old one was set to 140. If we had young'uns or old'uns around we'd consider turning it down. Then again, by the time the hot water makes its way alllllllllllllllll the way over to the guest bathroom, it's definitely closer to 120 anyway. In the master bath and kitchen, we'll just take our chances...
The International Building Code (IBC) defines Hot water as water at a temperature of 110² Fahrenheit. 100² is considered a comfortable bathing temperature. 120² is the highest recommended water heater temperature to prevent scalding. Dishwashers and clothes washers typically have there own elements to increase and regulate water temperature during use.
A few years back the city decided to require licensing of all rental properties (another money grab). One of the requirements (as a licensed Home Inspector) for rental licensing was a hot water temperature that was 110² minimum (from the IBC). The water temperature I measured was 100². A discussion with the woman of the house revealed that her husband showered first in the morning and that there was no hot water left for her. He used the hot water straight without dilution because of it's low temperature. When the tank temperature was raised the hot water needed to be diluted with cold for a comfortable bathing temperature and now there was enough hot water for the wife's shower also.
A few years back the city decided to require licensing of all rental properties (another money grab). One of the requirements (as a licensed Home Inspector) for rental licensing was a hot water temperature that was 110² minimum (from the IBC). The water temperature I measured was 100². A discussion with the woman of the house revealed that her husband showered first in the morning and that there was no hot water left for her. He used the hot water straight without dilution because of it's low temperature. When the tank temperature was raised the hot water needed to be diluted with cold for a comfortable bathing temperature and now there was enough hot water for the wife's shower also.
Hobby_Man22
Well-known member
I just mean that's what the faucets and shower heads are set at. You can always raise it yourself
Beerhippie
Well-known member
But... 110 degrees F squared is 12,100 degrees F!
Beerhippie
Well-known member
° Well, I'll be damned! I need to make me up a hidden character map!
I once had these things memorized....
I once had these things memorized....
Jim greengo
Well-known member
Around 125 is supposed to be the highest I can set them locally as a plumber anyway.
billt460
Well-known member
On the gas water heaters I've had, I've always set them to the low side of the "Normal" setting. On all of the electric water heaters I've had, I have never touched them. Whatever the factory setting was, the water always seemed hot enough. I've never measured any with a thermometer.
OP
JackOfDiamonds
Well-known member
Water control valve installed. Including thermometers for process control.
Hobby_Man22
Well-known member
I have a 50 gallon electric and you have to take a very long shower before the water starts to not be warm anymore. Waaay better then the 40 gallon gas water heater at my parents house
Maintaining 140deg+ will kill legionella and make your water heater inhospitable to bacteria. Maintaining below 120deg will be conducive to increased levels of legionella colony forming units with 95deg being ideal for dangerous levels of reproduction. In commercial buildings we run 145 and look for no lower than 125 return in the recirculation loop.
Hobby_Man22
Well-known member
So what about the cold water side?
Commercial environments are MUCH more likely to have stagnant water in pipes than residential unused areas, vacancies, recirculating loops, etc.
Isn’t it code now for homes to have thermostatic mixing valves at the tank? It’s a fantastic way to set the water heater to 140 and have it mixed down to 120.
We have our tankless set at 110-116F, depending on who’s in the shower.
PugetDude
ALLIANCE MEMBER
Two Rinnai tankless, both set at 125F
Getting ready to install another at our summer place.
Really happy with them.
Getting ready to install another at our summer place.
Really happy with them.
Hobby_Man22
Well-known member
On these on demand water heaters 140 is as high as they go, but that's too hot for a sink
dcg9381
Well-known member
What process control are you doing?
I never considered that. I wish I had known that when I was on a well.
Outside of this, as long as you have adequate "reserve" volume (gallons) I see no reason to heat a big tank of water any hotter than you need it to service the house. Seems like a waste of energy otherwise. I get it for those that need really hot water for dishwashers, etc.
I did a thermosphon (no pumps) 80 gallon solar water heater (roof mounted) with panels years ago. Plumber said that a mixing valve was required. I'm sure that part of it was that the temperature in the tank isn't regulated by a thermostat. 80 gallons and no sunlight, we could still get 3 days worth of hot water out of that system. I've never seen these in the US other than the ones I've installed. Common in central America... Gotta design your roof for loads for it though.
one of the neat things about electric storage heaters is the "double heating" feature of the design. it makes for some really fast recovery for the top of the tank.
LopezBart
Well-known member
Tempering valves (mixing valves) ensure that water supply lines don't see dangerously hot water, but water heaters can be turned up higher for more hot water and to avoid legionella. They're not compatible w/ circulating systems, though, unless one installs multiple tempering valves at the loop exits. Many modern shower valves have thermostatic limiters installed to prevent excessive water temperatures, of course.
RVs often use mixing valves since their hot water tanks are tiny (6-12 gallons).,
RVs often use mixing valves since their hot water tanks are tiny (6-12 gallons).,
It’s building code for new construction. We are not required follow new building code notes it enforced on our every day word living in existing buildings!