What is the "typical," Safe, temp. setting for the vertical style gas
fired house hot water heater ?
Wife is always complaining about not enough hot water, but am a bit
concerned about making the dialed temp., too hot, and perhaps increasing
the pressure in the tank too much, or making unsafe in some other way.
Mine is set to 130. You don't want to go below because of the possibility
of Legionaries bacteria that can thrive at 120 or less. You don't want to
go much hotter to avoid scalding. This is important with young children and
seniors that are not able to react to a very hot situation.
set tank to maximum after adding tempering valve that mixes hot and
cold water to produce output water thats not too hot.but can double
how old is the tank? and what kind of fuel?
electric can need new heater, gas can sludge up.....
was this lack of capacity always a problem?
No hotter than 120F, especially if there are elderly, small children or
handicapped people in the home. NO REASON for hotter water...if one
wants hotter water for dish washing, can always heat some on the stove.
Close, but these people way a little higher is better
Candada Savety Council
For example, temperatures under 50 C may increase the risk of Legionnaires'
disease, a form of pneumonia, due to bacterial growth in the tank. That
disease is caused by Legionella bacteria, which live in water. Temperature
is a critical factor for Legionella to grow. The risk of colonization in hot
water tanks is significant between 40 and 50 C
FYI, 50C = 122F I go for 130.
On Sun, 13 Feb 2011 13:12:09 -0500, "Ed Pawlowski"
How about jacking it above 140 and running the hot water down the
"Stout recommends temporarily turning up the temperature to above 140
Degrees F and running the hot water outlets for half an hour. Since
the bacteria quickly return, this should be done regularly, especially
if people prone to the infection are using the water."
But then you got this advice.
"Other risk factors for Legionnaires' disease identified by the study
included smoking, working more than 40 hours per week and spending
nights away from home."
I think I'm going to find something else to worry about.
Mine runs at around 180 degrees F. (first setting on hot). If you use
a dishwasher and have the temp too low there will always be a lag as
the thermostat in the dishwasher triggers the electric heater in it to
increase water temperature. One can use the highest setting for the
water heater but that wastes a lot of NG or power as the case may be.
This is not necessary or recommended.
Just make sure that kids are educated as how to run hot water safely
with the right cold water blending. If the kids are quite young then
lower the tank heater to around 140 degrees F. (medium low) to be on
the safe side.
I'd hate to see what the last setting is. That's hot enough to
scald someone. I'm with the 130 range folks. Hot enough for
the dishwasher and a reasonable supply of hot water, safe
from legionaires, but not dangerous and a waste of extra
You have to balance two competing objectives - hot enough in the tank to
prevent the bacteria causing Legionaries' Disease from growing but cool
enough at the tap to keep from scalding (antiscald valves not considered).
To do this, check the water temperature at the hot water tap furthest from
the tank. By furthest, I mean where the hot water must take the longest
path to get to the tap. This tap is likely to have the coolest hot water as
the water had the most chance to loose heat during its travel. Use a
drinking glass with a thermometer in it and let the water overflow the glass
until it is fully hot. You want 120 deg F which is the maximum temperature
various agencies have recommended to prevent scalding. Adjust the hot water
heater as necessary
Now, check the temperature setting of the hot water in the tank. If it
is above 130 deg F, you will have to live with it unless you want to install
point of use heating. If it is below 130 deg F, you will have to increase
it to that temperature as various agencies agree that 130 deg F is the
minimum temperature needed to prevent the bacteria causing Legionaries'
Disease from growing.
No opinion, just the facts - as far as the water heater itself is concerned.
You can safely turn the temperature up as high as it will go.
The whole system is designed to safely handle temperatures much hotter than
what you can direct via the thermostat. Further, there are backup
fail-safes, such as the pressure relief valve.
Downstream from the heater, if not hot enough, you'll risk death from
various diseases that thrive in merely warm water. Too hot, and you risk
death from scalding.
Other than that - and I don't know your wife - if the water temperature IS
adjusted to her liking, you may risk her complaining about something else
have a friend who feared his aging mom would get burned from hot
water, she couldnt really feel it.
so he added a tempering valve, otherwise called a anti scald valve,
but he fed his dishwasher before that valve and set his hot water tank
i forget the details but he said it doubled his tanks capacity and no
one could get burned, plus his dishwasher worked better than it ever
had...this also elminates the risk of legionaires disease.
i am surprised the feds havent made such a valve mandatory......
The downside to that is the water heater will be using more energy
because the heat losses during standby have increased significantly.
But if you need a supply of more hot water from a tank type, that is
the way to get it.
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