Gas Hot Water Tank Temps
 

I am trying to determine what the temp settings are on my HWT dial. See image included. What is each bar adjustment 5 or 10 degrees etc. Thanks for any feedback.

Model of Tank: John Wood GSW Superflue

Is the thick vertical red line after the word temp 120 degrees

http://farm8.staticflickr.com/7162/6...23e811a8e2.jpg

Heres a good write up on temps.
http://www.castanet.net/news/About-the-House-Hugh-Cairns/55635/How-hot-should-your-hot-water-be

You can measure it coming out a faucet. That will be more accurate anyway, then adjust it to where you want it.

Yes, use a meat thermometer if necessary.
If the water is too hot or too cold to register on your thermometers mix an equal quantity of water heater water WHW with water of a known temperature WKT.
Then the resultant temperature RT = (WHW + WKT)/2
2 x RT = WHW + WKT
WHW = (2 x RT) - WKT

Well i picked up a kitchen cooking thermostat and let the water run for a couple of minutes in a sink closest to the hot water tank and it got up to 138 degrees (ouch). Turned it down and will check the new setting tomorrow.

On my heater the distance between each tick mark is 10F according to the manufacturer.

I don't know what to think about the bacteria angle.
http://www.treehugger.com/green-food/is-it-safe-to-turn-down-your-water-heater-temperature.html

Maybe the CDC can come up with some odds on this. It seems to be slightly more than getting hit by lightning.
http://wwwnc.cdc.gov/eid/article/10/3/02-0707_article.htm

By comparison, yearly odds of getting killed on the highway in the US is about 33,000/190,000,000 = 1 in 5800.

Thanks for the help and links Wuzzat. Checked today and its down to 128 degrees, so each mark is indeed 10, thanks again.

150 at the tank is needed to keep bacteria from growing in the tank.
see correction below.

I don't often get to discuss risk with the guys at the gym so please indulge me. :p

According to Ropeik and Gray, "Risk is the probability that exposure to a hazard will lead to a negative consequence."

The risk of being burned is pretty clear once exposed to hot water, as shown above. On the other hand, once burned-twice shy.

With bacteria in the WH the risk is not that all that clear and the exposure to the hazard and how hazardous it is (how many die per 100,000 people per year or during their lifetime from hot water heater bacteria?) is also kind of murky.

I guess I'd leave my heater at the min temp recommended for my dishwasher, 120F.

But I may be biased because I spilled hot water for my coffee on my hand and got second degree burns and had to use
http://en.wikipedia.org/wiki/Silver_sulfadiazine
and the skin color of that hand is still not normal. :(

Sorry I ment 120. In fact it is 45c which is 114f and no more than 60c which is 140f