Adjusting water temp

[tinglett]

I have a 2019 2108DS TT with a 6 gallon water heater (Atwood, if I recall). I don't believe there is an adjustment for water temperature, and yet the water is super hot.

So I tried something that may be stupid and thought I'd put it out here to find out why! As you can see in the picture, I "tweaked" my bypass valves to allow some cold to circulate around the hot. Note the hot output is slightly closed and the bypass from cold is slightly open while the cold supply into the tank remains wide open. I was really curious if this would work...and it did! I tweaked the water temp down about 10 degrees F and it seems to be holding just fine for the kitchen and the shower. These ball valves probably aren't really made for flow-control so I was a little concerned they might leak. But I was thinking if this really worked I could add an additional valve(s) for this kind of control.

Now there must be something wrong about doing this. Does anyone know?

Todd

[tinglett]

I should point out that I've only run the water heater on electric so far (about a month) and not gas. Not sure why that would make a diff. Also, perhaps more importantly, I have been connected to city water so far so maybe there might be an issue with a pump trying to circulate water. I should test that.

I haven't tried to measure power usage to see if the water heater is running more often, either.

Todd

[Morich]

A few points to consider and look at how you plan to use the water. One is that the lower temp will mean the hot water runs out quicker, so two showers in a row may let the second person get pretty cool. One reason RV heater are set higher is to let us use less hot and more cold as a way to extend the time we can shower on the little bitty six gallon tank.
Another thought is how long we can run hot water will vary with what the water temp coming in has in different places. Some part of the country have lines buried deep to avoid freezing while other places like the South are buried so shallow that we may get hot water out of the cold faucet for a bit.
Ball valves partly closed tend to erode at the edges of the ball when not fully opened but that it kind of slow and we often don't run that much water in an RV to make the change come around too often.

[Goodspike]

They do make mixer valves for this exact purpose on home water heaters. Some are set higher than 120 to avoid Legionaries Disease.

[tinglett]

BTW, I did just run out and try out the pump. It didn't seem to behave any different, though I haven't used it in a couple months so I still may be missing something.

I was wondering about volume of hot water as well. My thinking is that I actually get a larger hot water supply rather than less as the water going through the bypass means (in theory) less hot water is extracted from the tank while the water flows. I'd have to do some experiments to see if that's really true.

I had heard of valves designed for this purpose and this is what gave me the idea. I'm still thinking there is something not quite right about it, though. I should make sure the water isn't somehow convecting around when water isn't normally flowing. Not sure how to test for that, though, but a check valve might solve it if it happens.

I do have to say I like the water a bit colder. I have the heater turned off right now so I can't measure, but I'm thinking it was maybe 135F and I "turned it down" to 125F as that is where I run it in my house.

Todd

[Morich]

I find I just need to work it a bit different when in the RV. At home we have a recirculation pump to move water from the heater to the bath as it is a long run in this house making the operation different as we turn on the pump timer when we are ready to use hot water and then are waiting for the water to be warm, so getting the right temp is more a matter of waiting for warm instead of cool. But in the RV, we always open the cold first and then crack the hot open further as needed since it is such a short run from heater to shower. We are also much more aware of conserving the water both in the heater and as it fills the grey tank.
Part of the "trauma" of roughing it!

[Goodspike]

Originally Posted by tinglett

I was wondering about volume of hot water as well. My thinking is that I actually get a larger hot water supply rather than less as the water going through the bypass means (in theory) less hot water is extracted from the tank while the water flows. I'd have to do some experiments to see if that's really true.

I think that's the main, if not only reason they set the tanks so hot. 6 gallons only goes so far, but if it's at 160 degrees you'll get more than 6 gallons of 120 degree water with a mix of hot water and cold water.

[creativepart]

Are you aware that there are replacement thermostats that have temperature adjustments built into them?

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

[tinglett]

Originally Posted by creativepart

Are you aware that there are replacement thermostats that have temperature adjustments built into them?

No I wasn't aware of these...thanks! The amazon comments are a little disturbing, though. Looks like it's an easy install for some and a total failure for others. I'll start digging around and learn more. I like the idea of not heating the water so hot in the first place, but then I suppose we'll run out a little faster. But it'll save propane when I don't have shore power.

This also reminded me to have a peek at things like the showermiser. There's always another gadget, isn't there?

Todd

[Morich]

Originally Posted by creativepart

Are you aware that there are replacement thermostats that have temperature adjustments built into them?

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

Still another item that I had not looked fro and was not aware of being out there. Always good to find new things as we might need them later.
Thanks for throwing that into the discussion.