Atwood hot water heater -- Too darn hot

fourthclassC wrote:
Howdy, How every one is holding up with the current situation.
My how water is too hot. Thinking about getting the adjustable disc thermostat from Atwood. I've seen them for 35 to 50 dollars. Saw some folks added thermo conductive compound where the "disk" contacts the tank . Has any one used these to lower the water temp? Interested in all and any comments. Thank You

Hi,

I'll offer something not said yet.

There is the possibility your heater may be overheating the water due to hard water scale buildup inside the heater. A quick way to know for sure what your water temperature is, is to actually measure the water temp. Do not assume the heater is working to factory spec.

At the bath or kitchen sink, whichever is closer to the water heater would be better, run the hot water only enough that is it very hot and check the temperature with a thermometer you know is accurate. Cooking thermometers will work as they go high enough in temperature. They can be checked by testing when water on the stove boils, which is 212F unless you are very high above sea level.

If you find the water is a lot hotter than 140F, it may be the scale build up in the heater. A buildup of scale over the years can slow down the rate at which the water temperature gets to the sensor on the outside of the tank and make the water hotter.

If your profile is up to date, your water heater is from 2003. And if your water heater tank is still original, that is a good many years of potential scale build up unless you have a portable water softener. Which many or most do not.

Atwood has a procedure on doing a vinegar boil out of the heater to help reduce the scale. I have done this boil out on 3 different water heaters since I learned of it a year ago, and every one of those heater now warms up and shuts down faster then the owners can ever recall.

Point being, do some troubleshooting first to see what the problem may be. Installing an adjustable T stat or a water mixing valve may not be the right fix.

Hope this helps

John

WA State law is for a residence not an RV.

dougrainer wrote:

1. I always wonder where people think there is a "code" or "Legal Limit" for things. THERE IS NO LEGAL TEMP LIMIT FOR WATER HEATERS. There is a 125 psi PRESSURE limit in most codes for water heaters.
2. The REASON for 130/140 Auto set Tstats on 12 volt DSI RV water heaters is simple. To get the MAXIMUM amount of hot water(mixing cold with hot) they use the 130/140 auto set Tstats.
3. There are RV water heaters that have a 160 degree tstat and that model has a auto-mixing valve on the exit on the back of the water heater that drops the temp to about 120. BUT, it is adjustable and you can fiddle with the adjustment to get hotter or colder output water.
4. Pilot Controlled RV water heaters do have an adjustable Tstat.
5. The BEST solution for the OP is to buy the aftermarket Adjustable Tstat kit. Doug

https://www.amazon.com/Atwood-93105-Adjustable-Electronic-Thermostat/dp/B001BZ36HM

I tend to shy away from absolutes. There are laws in some states and local areas. For instance the state of washington. According to inspectopedia, a number of states have adopted codes with a 120 degree maximum. I believe some locations, especially other countries, have minimum temperature regulations to prevent bacteria and legionnaire's disease.
I know there will be another set of people who want to argue over whether these apply to RVs. Personally, I don't think most of us are really concerned about "regulations".

I'm also hesitant to make blanket statements about what is "BEST" because everyone's situation is different. BEST for you is what works for you and there are many factors that go into deciding what's best. For many, as some have suggested, "BEST" is to do nothing and mix more cold water with the hot. It's certainly the cheapest and requires no physical changes. But there are obvious drawbacks of potential scalding hazard and not being able to keep regulated temperatures. Obviously, I think the OP was aware that was an option and was looking for a "better" solution for his purposes.

An adjustable thermostat is cheaper than a mixing valve and doesn't require plumbing changes, but it does have potential downsides. The two biggest are less hot water and the risk of bacterial growth with lower temperatures.

Mixing valve with anti-scald isn't cheap, but it's cheaper than a new water heater. It does require plumbing though. More work to install. For my purposes, this is a better solution. The OP will obviously have to decide what the "BEST" solution is for his situation.

Mike134 wrote:

Maybe you mis-read my post. What you describe is exactly what I had - a shower head with an on/off button. Despite this, when turned back on it was all hot for a few seconds. So it wasn't that I had to readjust the valves - they were already adjusted. I am just thankful it wasn't my son that got burned.

My shower head with the push button does the same thing. Not sure how the water remains circulating but it's just a straight hot water blast till the tempered water mixes in a few seconds later. Must be a design flaw since we both have had that happen

**********End Quote (quote function isn’t working right)**************

That’s exactly what mine was doing. Didn’t matter if it was the type of on/off valve that let the water dribble or the type that turned it off completely.

I’ll recommend it one more time: thermostatic mixing valve. Fixed it, done. It reacts to changes in water temp and flow instantly. One of the best mods I’ve done on my TC, despite the fact that mine was more difficult due to space limitations.

:):)

Maybe you mis-read my post. What you describe is exactly what I had - a shower head with an on/off button. Despite this, when turned back on it was all hot for a few seconds. So it wasn't that I had to readjust the valves - they were already adjusted. I am just thankful it wasn't my son that got burned.

My shower head with the push button does the same thing. Not sure how the water remains circulating but it's just a straight hot water blast till the tempered water mixes in a few seconds later. Must be a design flaw since we both have had that happen

way2roll wrote:

MDKMDK wrote:

enblethen wrote:
Adjust temperature of water by turning down hot and turning cold on. Hot water will last longer.

Bingo. Best answer.

Good answer to a point. In a former MH despite adjusting the temperature, when taking a Navy shower and turning the handle off to conserve water, when turning it back on, for a few seconds it was all hot. Now this was probably a cheap mixing valve, but that's not the point. If you didn't remember each time you turned it off to direct the water away from you, you got blasted with water that had to be well beyond 120. I forgot once and ended up with burns on my chest and blisters. A WH that only heats to the legal 120 would have prevented that. Why aren't RV water heaters confined to the same specs? So while correct water mixture is a reactive way to prevent scalding, it's not preventative.

1. I always wonder where people think there is a "code" or "Legal Limit" for things. THERE IS NO LEGAL TEMP LIMIT FOR WATER HEATERS. There is a 125 psi PRESSURE limit in most codes for water heaters.
2. The REASON for 130/140 Auto set Tstats on 12 volt DSI RV water heaters is simple. To get the MAXIMUM amount of hot water(mixing cold with hot) they use the 130/140 auto set Tstats.
3. There are RV water heaters that have a 160 degree tstat and that model has a auto-mixing valve on the exit on the back of the water heater that drops the temp to about 120. BUT, it is adjustable and you can fiddle with the adjustment to get hotter or colder output water.
4. Pilot Controlled RV water heaters do have an adjustable Tstat.
5. The BEST solution for the OP is to buy the aftermarket Adjustable Tstat kit. Doug

https://www.amazon.com/Atwood-93105-Adjustable-Electronic-Thermostat/dp/B001BZ36HM

It is very inefficient to spend money heating water way too hot, then using cold water to cool it off, really,.....just plain stupidity IMO

You want the really hot water so that you can add lots of cold to it and make it last longer. Also if you start with the hot all the way on, let it get hot, then add the cold you won't have the varying temps all the time like you do when hot is partially on.

Atwood standard models use a fixed temp set of t-stats
Normal controlling t-stat opens at 140*F & closes for reheating at 110*F
ECO (Energy Cut Out---HIGH temp t-stat) TRIPS open at 180*F/locks out any futher heating cycles and triggers a RED Fault light. *To reset you turn on/off switch OFF then back ON

Atwood XT model uses a 155*F fixed temp for the normal controlling t-stats
ECO remains the same 180*F trip/lock-out/Fault light scheme
Uses a mixing valve that the hot goes to and is mixed with cold from cold inlet line to control output temp to 130*F (factory set then plugged)

Atwood has an 'optional' fixed normal t-stat (130*F) and an 'optional' adjustable normal t-stat
ECO's remain fixed at 180*F



Suburban has separate sets of t-stats for 120VAC (electric) and for the 12VDC (propane)
Normal controlling temp t-stat opens at 130*F & closes for reheat cycle at 100*F
High temp t-stat trips at 170*F and has a manual reset button on it.

Suburban has an 'optional' t-stat for both the 120VAC and for the 12VDC set.....but they are 140*F (10*F higher then OEM)




Optional lower temp t-stats are no-longer available...go figure!

Just remember
Normal temp t-stats control the heating cycles ---open and close routinely
High temp t-stats are 'SAFETY' backup to shutdown all heating if normal t-stats fail ----open/trip and have to be reset manually
T&P Relief Vlaves are backup/backup SAFETY Devices should t-stats (normal/high) completely fail to shutdown all heating. Blow open at 210*F/150psi which relieves pressure and allows WH Tank to be flooded with rush of cold inlet water.

MDKMDK wrote:

way2roll wrote:

MDKMDK wrote:

enblethen wrote:
Adjust temperature of water by turning down hot and turning cold on. Hot water will last longer.

Bingo. Best answer.

Good answer to a point. In a former MH despite adjusting the temperature, when taking a Navy shower and turning the handle off to conserve water, when turning it back on, for a few seconds it was all hot. Now this was probably a cheap mixing valve, but that's not the point. If you didn't remember each time you turned it off to direct the water away from you, you got blasted with water that had to be well beyond 120. I forgot once and ended up with burns on my chest and blisters. A WH that only heats to the legal 120 would have prevented that. Why aren't RV water heaters confined to the same specs? So while correct water mixture is a reactive way to prevent scalding, it's not preventative.

Yup. There's no such thing as an idiot proof water heater. In that case, a shower head with an on/off "navy shower" button is recommended, so you don't have to adjust the mix at the taps/valves. (sorry, not implying anything, just using colorful relevant phraseology :B)

OxyGenetics not only has a good shower head it does not compleatly shut off and eliminates the blast of hot water.