How hot on water heater setting?

ragkar · Oct 30, 2007

120 degrees is the minimum recommended temperature that will sterilize pots and pans. You can check it with a meat thermometer.

Rara Avis · Oct 31, 2007

Now of days most new water tanks lower thermostat can heat water up to 170 degrees F and the upper has a limit of 160 degrees F...

You set your tank internal thermostats to make sure there is no legionella...

The final temperature will be fine tuned by the external anti-scald valve that is required on New Water Tank Installations...

No kids and no sue happy visitors...you can turn the anti-scald OFF...but you did NOT hear that from me...

Something to think about when you set your water temperature...Dishwasher...
A "booster" heater can increase the temperature of the water entering the dishwasher to the 140 degrees F recommended for cleaning. Some dishwashers have built-in boosters that will automatically raise the water temperature, while others require manual selection before the wash cycle begins. A booster heater can add about $30 to the cost of a new dishwasher but should pay for itself in water-heating energy savings in about 1 year if you also lower your water heater temperature. Reducing the water heater temperature is not advisable, however, if your dishwasher does not have a booster heater.

Richard · Oct 31, 2007

If a heater has dual elements (mine does), and evidently, if it has dual thermostats (someone said mine will, I've not looked yet) then....

The numbers on the thermostat I DID see where basic numbers and the dial is in BETWEEN them so I don't know it's real setting without putting a thermometer to it.

That said... if I indeed have two thermostats, I'd supppose I'd want to set them identical or as close as my eyeball will allow?

If there is a difference, do I want to by design, have one over the other, hotter? (for example, the lower one so the bottom is at "finished temp"?

Going to tinker more on this tonight after work.

kenmac · Oct 31, 2007

set both thermostats the same( assuming elec. water heater) unless your owners manual tells you( some do ) the temp. for . # 3 = 120 deg. etc, then, you will have to go with the thermometer method.

dmccarty · Oct 31, 2007

Richard our water heater has two elements but only one is used most of the time. I think the second element turns on if we use lots of hot water and the heater needs to recover.

Are you sure you faucets are not the problem and not the water heater? I know the faucets in the new house can be adjusted to limit the hot water temperature. We are on a well as well, say that fast three times, and having hot water for a shower has not been a problem. I can get out of the shower looking like a cooked lobster...

Later,
Dan

Richard · Oct 31, 2007

Hey Dan,

Yeah, I presume the issue can't be at the faucet as I had the cold water 100% turned off (at a shutoff in closet) so I was only being fed hot water...

I'll admit that it DID seem the water would be a bit more hot at the kitchen sink than it seemed to be here.

I'm going to measure the temp at the kitchen sink and then remeasure the temp at this shower (hot only). They should be the same I'd suppose.

One more thing I've thought of... I've got 3/4" pipes coming to a 3/4" THROUGHPUT mixer valve. I can take one of the shutoff valves and close it about half way or so. That might allow me to further limit the amount of cold water coming here.

One issue I think is being on a well. I was going to get an in line heater (continuous?) but the guy at the plumbing place said it wouldn't work very well for me since they're only designed to raise the water temp a certain amount and with me on a well, he didn't think it would raise it enough.

(later I heard about putting two in line together??? but he never mentioned that and now it's essentially, too late)

I DID have another thought....

Could someone put a continous heater in line AFTER their water heater tank?

I'd speculate that would let them use the tank to hold a lot of "hot" instead of HOT water, the inline would raise the prewarmed water "up to temp" and both elements in the tank would allow a stronger warming/heating of the water from my well.

Any validity in that logic?

tlbuser · Oct 31, 2007

If it's a single lever (hot/cold) valve, the valve body could be installed incorrectly.

SnowRidge · Oct 31, 2007

120F is where ours is. Our Bosch built Kenmore dishwasher heats the water to a higher temperature, so we don't have to worry about it. I can verify that 140F will kill some faucet washers.

ragkar · Oct 31, 2007

I'm no longer living in a house with a hot water heater, but let me tell you about furnaces with built in hot water heaters (which I now have).
Most people assume that the cold water is piped directly to the cold faucets and the hot water goes directly from the furnace to the hot faucets. That is not the case as the water out of the furnace/hot-water-heater is much too hot to use on human skins.
If you will look at an installation of this type you will find maybe a dozen valves with the usually blue spider web knob. Eleven of these valves are shut-off and have two pipe connections (in and out). There is one valve that has three pipes and that is the mixer check valve. The purpose of this valve is to add cold water to the extremely hot water from the furnace. One of the three pipes is attached to the cold water pipe (you can check this visually or by touch). A second pipe goes to the furnace heater and is the inlet for the extremely hot water. And the third pipe is the outlet going to the sink/bathroom etc.
The check valve portion of the mixer/check valve is to prevent hot water from entering the cold water pipes. It operates as a ball-seat and spring retainer to permit only one way water flow for the cold water side.
All you have to do to change the water temperature is turn the valve. One woman I know suffered for eighteen years with luke warm hot water. After I told her this she went into her basement, turned the knob and has been happy ever since with the water temperature.
I'd suggest a cautious approach. Run both hot and cold water from your faucet for a minute or so. Then go into the basement and identify the pipes by touch. Be careful for the extremely hot one. Identify the three pipe valve and turn it a bit. Then go upstairs and check the temperature by touch or a meat thermometer. As I said in an earlier post, you are shooting for 120 degrees. Even that is rather hot to my touch.
You might find it necessary to fine tune this setting summer and winter when the cold water temperature will vary.
If there are any plumbers in the crowd, feel free to correct me.

RonMar · Oct 31, 2007

Richard said:
If there is a difference, do I want to by design, have one over the other, hotter? (for example, the lower one so the bottom is at "finished temp"?

Going to tinker more on this tonight after work.

Just like warm air rises to the ceiling, warm water rises to the top of the tank. Because of this, that is where the hot water is drawn from. The cold water inlet has a pipe that delivers the cold makeup water to the bottom of the tank. A typical water heater will have two elements, each with a thermostat. Set them both at the same temp. Because of the wiring, only one will run at a time, with the lower unit being a slave to the upper one. If you look at the label on the hot water heater, it will probably say something like:
Upper element 4500W
Lower Element 4500W
Total 4500W(because only one can run at a time)

As you use hot water the level of the cold water being fed into the bottom of the tank rises. When it reaches the lower thermostat, it turns on that element to start making warm water. This water being warmer than the surrounding water rises toward the top of the tank. If you use enough hot water fast enough, the cold level will rise high enough to activate the upper thermostat. The lower element running delays this as the column of hot water rising from the lower element flows right past the upper thermostat. As soon as this thermostat kicks on, it cuts off the power to the lower thermostat. It's colum of rising hot water flows directly up toward the hot water outlet from the tank.

When you stop using hot water, the upper element continues to heat the tank till the heat layer lowers enough to turn off the upper thermostat. As son as it shuts off, it connects power to the lower thermostat that continues to heat the water down to the point where it shuts off. A little bit of conduction warms it down a bit below the lower element with a cool layer left on the bottom. As the tank radiates heat, the coolest water slides down the outer case and pools in the bottom till that level rises high enough to kick in the lower element. That is why the lower element usually burns out first, it gets more use. In fact, I don't recall ever swapping out an upper element.

I set mine for just a little over 125F This yields around 130F outlet water temp. Unless you have a really old dishwasher, it probably already has a water heating element built in. they are pretty standard these days.

Richard · Nov 1, 2007

Ron, very nice description, thanks!!

I moved BOTH thermostats to the "middle" last night. The middle defined as between the 125 and 150 mark. Guess I'll try it there for while & see what happens.

Rara Avis · Nov 1, 2007

RonMar said:
I set mine for just a little over 125F This yields around 130F outlet water temp. Unless you have a really old dishwasher, it probably already has a water heating element built in. they are pretty standard these days.

Water temperature is a key element in achieving clean dishes. A dishwasher's heating element is not designed to heat the water that enters it. Rather, the heating element is designed to maintain the heat of the water that enters the dishwasher. Its a good idea to run the hot water in your sink for a couple of minutes before you run the dishwasher. Just to make sure the water is nice and hot before it enters the dishwasher. If the water is unable to stay hot, it can adversely affect your dishwasher's cleaning ability.

SnowRidge · Nov 1, 2007

PaulChristenson said:
Water temperature is a key element in achieving clean dishes. A dishwasher's heating element is not designed to heat the water that enters it. Rather, the heating element is designed to maintain the heat of the water that enters the dishwasher. Its a good idea to run the hot water in your sink for a couple of minutes before you run the dishwasher. Just to make sure the water is nice and hot before it enters the dishwasher. If the water is unable to stay hot, it can adversely affect your dishwasher's cleaning ability.

Our dishwasher has an inline heater. It is specifically designed to heat the incoming water. Says so right in the manual.

Richard · Nov 1, 2007

I simply let my dogs lick my plates clean before I put them away. The wife of course, doesn't much care for it when I do that!

SnowRidge · Nov 1, 2007

Richard said:
I simply let my dogs lick my plates clean before I put them away. The wife of course, doesn't much care for it when I do that!

Not only that, but the Tellico Improvement And Ladies Snail Darter Chowder Marching Society will be striking you off their guest list, now that you have made this public announcement.

LBrown59 · Nov 1, 2007

Oh Kay:
Now that we've heard it for the Elect. hot water heaters' what about the gas ones ?

RonMar · Nov 1, 2007

PaulChristenson said:
Water temperature is a key element in achieving clean dishes. A dishwasher's heating element is not designed to heat the water that enters it. Rather, the heating element is designed to maintain the heat of the water that enters the dishwasher. Its a good idea to run the hot water in your sink for a couple of minutes before you run the dishwasher. Just to make sure the water is nice and hot before it enters the dishwasher. If the water is unable to stay hot, it can adversely affect your dishwasher's cleaning ability.

The heating element in ours actually raises the temp inside to around 140 ish if I recall the manual correctly. The tip about running the kitchen sink hot water is an excellent one though, provided of course that the dishwasher is plummed off that hot line, which it usually is

We do this every time we run it as it saves wear and tear on the internal heating element.

Richard, my wife isn't too keen on the doggie dishwasher either

Bird · Nov 1, 2007

OK, you fellers made me curious. I knew our water didn't get hot enough to hurt me and I like it that way, so I just now did some checking. We have a 50 gallon dual element electric Rheem water heater and, according to my thermometer, the water only gets to 118 degrees. The manual for our KitchenAid dishwasher does say that if your water temperature is less than 120 degrees to get a qualified person to raise the water heater's thermostat setting. And of course in the efficiency tips, the manual does say to run the water at the nearest faucet to get the hot water there before turning on the dishwasher.

Now I don't know about being "qualified", but I have adjusted water heater thermostats; however, Soundguy said "If you have kids or elderly . . ., the 'safe answer is to set the water temp lower than 'scald' level." I probably meet that "elderly" qualification. And as LBrown59 said, "We set it where we can comfortably wash our hands under the hot water faucet with out having to turn the cold water tap on." Yep, that's about where ours is set.

ultrarunner · Nov 1, 2007

PaulChristenson said:
Water temperature is a key element in achieving clean dishes. A dishwasher's heating element is not designed to heat the water that enters it. Rather, the heating element is designed to maintain the heat of the water that enters the dishwasher. Its a good idea to run the hot water in your sink for a couple of minutes before you run the dishwasher. Just to make sure the water is nice and hot before it enters the dishwasher. If the water is unable to stay hot, it can adversely affect your dishwasher's cleaning ability.

Paul, I thought the same thing until I hooked up my European made Washing Machine and DishWasher.

The Washing Machine has only one water inlet and it is for cold water. The Washing Machine has an adjustable thermostat knob that adjusts the water temp from 70 F to 212 F. The washer is a front loader and the door has an interlock to prevent opening until 60 seconds after the spin cycle is complete.

The installation instructions for the dishwasher state it has an in line heater and also states hot water hook-up not required.

Both units are Eudora.

Piped hot water in Europe from a storage tank is not universal. Many homes still have electric, point of use water heating.

Rara Avis · Nov 1, 2007

ultrarunner said:
Paul, I thought the same thing until I hooked up my European made Washing Machine and DishWasher.

The Washing Machine has only one water inlet and it is for cold water. The Washing Machine has an adjustable thermostat knob that adjusts the water temp from 70 F to 212 F. The washer is a front loader and the door has an interlock to prevent opening until 60 seconds after the spin cycle is complete.

The installation instructions for the dishwasher state it has an in line heater and also states hot water hook-up not required.

Both units are Eudora.

Piped hot water in Europe from a storage tank is not universal. Many homes still have electric, point of use water heating.

Yes, you are absolutely correct about piping just cold water to a location...European designers are big advocates of ON-DEMAND Local hot water at the use point...