Lukewarm water from water heater

[Jayne-O]

Hi Everyone. Hey our 2017 305RL water heater only heats to lukewarm. It used to heat much hotter to the point that I'd have to hurry and mix cold with it. That hot. But now it only goes to a lukewarm such that you wonder if you want to shower in it. I did a number of tests: after I had drained my hot water heater, rehooked up city water, flushed lines. I first put the electric heater on for 1.25 hours. Lukewarm. (I ran the faucets for quite awhile to drain some off.) Then ran electric and gas heater. After an hour, lukewarm. Drained off a bunch more water. Gas kicks back on (with electric still on), still lukewarm. Does it sound as if my thermostat is giving out? Can I still use the water heater with both gas and electric so I at least have non-cold water? Safe? Thank you.

P.S. I did read the files available here, but none helped for my situation.

[PeteandJoan]

Mine did the same thing. Most likely the thermostats are bad. Ordered all parts from Amazon. Replaced both thermostats, Electic Heating element, Off-on switch, anode rod. Also gave the tank a very thorough flushing...lots of gunk. Only trouble I had was that the factory used wiring a little too short and had trouble getting connectors back on without splicing new wire. About $60-70 and free shipping in about 2 days. Works good just setting in driveway. Real test to come later...I hope. More help & ideas coming soon.

[Charlie 3931fb]

Had all most the same problem with mine. Our's was going to every temperature when taking a shower (hot, cold, warm back to hot ect.) . Took it into a CW and they replaced what they called a mixing valve somewhere in the heater. Works great now.


Charlie

[PeteandJoan]

Please let us know what the problem was when you find it.

[Jayne-O]

Oh my gosh ya'll. I couldn't believe the fix for this. I posted in another group on Facebook also. It's a Montana Owners group. Turns out that my recent habit of turning off the shower via the shower head, versus the handle (valve on the wall) was the issue. There is a back flow of water when you do that that keeps hot and cold mixing in the tanks, hence causing lukewarm water. Seems like a design flaw. Here is what one of the posters said: "With both hot and cold shower handles on and the shower head closed the difference in pressure for each hot and cold feed allows cold water (stronger pressure) to mix with the hot and temper it down. Glad you found the problem. The only way to prevent it is to put a check valve on the shower hot water side. This would prevent "back flow" of the hot water to the rest of the RV hot water lines." And here is what another poster said: "it's mixing when actual valve is left on and just shower head off. Same with inside and outside shower."

They saved me lots of money, because when I called my dealer, he said they'd likely replace the thermostat and whatever else they thought needed replacing.

Whew. Thank you all for your replies.

[Jayne-O]

So Charlie I wonder if you were doing what I was doing: leaving the valves open, but closing water flow by closing off the shower head button.

[PeteandJoan]

WOW. Good catch. We will be sure not to do that in the future. I was just about to go out and replace that "mixing Valve" too! Maybe later now.

[Preston & Terri]

I seem to remember the same thing can happen if the outside shower valves are both open. If you have the hose connected for example with garden sprayer connected, you wouldn't know the valves are open unless you checked them.

An easy way to check if the water in the heater is actually hot is to lift the pressure relief valve, (careful not to burn yourself) if the water is hot the problem is not the water heater but somewhere else in the system.

[uhftx]

Originally Posted by Jayne-O

So Charlie I wonder if you were doing what I was doing: leaving the valves open, but closing water flow by closing off the shower head button.

So I assume by using the outside shower in the same manner would generate the same issue. Seems logical. Maybe the newer ones do not have the outside shower shut off button. But Mine does and I use the shut off button. The kids when they visit can't reach it. So I have never noticed this effect.
Amazing the things you can learn from the great people here.

[Charlie 3931fb]

Originally Posted by Jayne-O

So Charlie I wonder if you were doing what I was doing: leaving the valves open, but closing water flow by closing off the shower head button.

I was getting all kinds of temperature changes with the shower valve open and water running WAS NOT shutting down at the shower head

Charlie

[gjennings]

I’m having a Luke warm water issue when the water heater is on electric. When on gas it’s nice and hot. Any ideas for that?

[mhs4771]

If you have the Suburban Hot Water heater, they use two t-stats, one for gas and one for electric. Sounds like your electric t-stat is failing. I just had to replace our electric side because of the same exact issue.

[Bill M]

Depending on how many valves you have to close you hot water heater for storage, if one is still not in correct position, then you will have a mixture of hot & cold water going to your faucets. Had that problem in my older TT till I turn the third valve to correct postion.

[Ruffuslike]

'So Charlie I wonder if you were doing what I was doing: leaving the valves open, but closing water flow by closing off the shower head button.'
Did it really help? As I had the same problem.

[DutchmenSport]

Outside showers / faucets will do the same thing. Always turn the knobs off, otherwise hot and cold mix. This is not a design flaw. Campers have been doing this for at least the last 20 years (I'm not exaggerating).

[airboatart]

Yes check outside shower valves mine got turned on some how drove me crazy trying to figure out my hot water was luke warm.