New 3761FL water heater issues

[KBMKVIII]

Hello everyone.
New rv owner here.
‘22 3761FL brand new.
Please be patient with me.
I picked up this unit and moved into it immediately.
The electric water heater initially turned on when picked up.
12 gal tank.
Turned electric heater on and no hot water.
Even after 4 hours.
Found that the fuse, not breaker, had blown.
Replaced fuse.
Turned heater back on.
Fuse has continuity.
Breaker on.
Still no heat.
Checked fuse and breakers again.
Went to turn the gas on with the electric to quickly heat the tank and immediately had a fault light come on.
Turn the gas heat switch off and it goes away.
Could someone please point me in the right direction where to look?
I am quite competent electrically/mechanically and have plenty of tools.
I would take it back to the dealership but with me and the wife and all of our belongings in it I do not have that ability.
And we need a hot shower haha.
About to drain the tank tonight to see if the heating element even comes on.
50A hookup.
Thank y’all!

[Stumpy75]

You mention that you are going to drain the tank, so I will assume that at no time did you turn the electric element on with no water in the tank. That's almost an immediate burnout of the element if you had no water in the tank. The blown fuse makes me suspicious...

Turning it to gas might give an immediate fault if there is no gas at hot water tank. Cycle it through multiple times in order to get propane through the lines and to the tank.

Others on this forum might be able to help with problems other than those above.

Since it IS new, a call or trip to your dealer might be in order.

[bobbecky]

I'm guessing this is a Suburban water heater. If so, outside behind the water heater cover, at the lower left corner there is a small rocker switch. It may be switched off and be aware that the switch is always installed upside down from what you would normally expect it to be positioned. It turns on the 120 volt power to to the electric side of the water heater. As for the DSI fault light, it will always come on when you turn on the gas switch if the water is cool enough, and as soon as the flame is lit, the light will go out. This is perfectly normal, and to get the fastest recovery time heating water, like if there will be people needing showers right after each other, these water heaters are designed to have both the electric and gas turned on at the same time. Enjoy your showers. Oh, and welcome to the forum.

[chuckster57]

Originally Posted by KBMKVIII

Hello everyone.
New rv owner here.
‘22 3761FL brand new.
Please be patient with me.
I picked up this unit and moved into it immediately.
The electric water heater initially turned on when picked up.
12 gal tank.
Turned electric heater on and no hot water.
Even after 4 hours.
Found that the fuse, not breaker, had blown.
Replaced fuse.
Turned heater back on.
Fuse has continuity.
Breaker on.
Still no heat.
Checked fuse and breakers again.
Went to turn the gas on with the electric to quickly heat the tank and immediately had a fault light come on.
Turn the gas heat switch off and it goes away.
Could someone please point me in the right direction where to look?
I am quite competent electrically/mechanically and have plenty of tools.
I would take it back to the dealership but with me and the wife and all of our belongings in it I do not have that ability.
And we need a hot shower haha.
About to drain the tank tonight to see if the heating element even comes on.
50A hookup.
Thank y’all!

DO NOT drain the tank to test the electrical element, you will burn it out in short order.

When you switch on the gas, the fault light will be on until it lights and then the light goes off.

Can you post make and model for more precise troubleshooting.

[KBMKVIII]

I believe it’s dometic.
I’ll get model number after work.
Any way to test the element?
Like a resistance test?
And thank you all

[KBMKVIII]

Just watched a video for testing the heating element.
Going to ohm it out tonight.
Any recommendations where to get an element if it’s bad?
Obviously I’ll match the watts and voltage.

[chuckster57]

Home Depot, Lowes will have them.

Dometic (Atwood) water heaters have the element on the back side. If you can gain access to the back, look for the black junction box. Unplug from shore power and make sure all the connections are good. I’ve lost count of how many times one of the 110VAC wires has come loose.

[sourdough]

All I've seen in 12 gallon water heaters on Keystone RVs were Suburban. Does Dometic even make a 12 gal. water heater? I've seen 6, 9 and 10 but never a 12??

[chuckster57]

Originally Posted by sourdough

All I've seen in 12 gallon water heaters on Keystone RVs were Suburban. Does Dometic even make a 12 gal. water heater? I've seen 6, 9 and 10 but never a 12??

I work on so many different brands/models I quit trying to know what gets put in each one.

[bobbecky]

The fifth wheel model he posted is a Montana, so it's highly unlikely that the water heater is anything else but a Suburban. That's why I posted a description of what he needed to check before he started tearing into things. That little black rocker switch confuses many people and it's unlikely it would have been mentioned when he bought the trailer. They also wouldn't mention the DSI fault light.

[sourdough]

Assuming OP has a Suburban 12 gal. water heater;

Check that black rocker switch in the lower left hand corner. Pay attention to it as it operates upside down. It should be on. If it is and still doesn't work;

Turn off the breaker to the WH and pull out the little rocker switch, it just snaps in. Check (ohms) to see that the switch opens and closes the circuit. If it works make sure you have 120vac to the rocker switch with voltage applied. I have had 2 of these switches melt, freeze up and fail to provide continuity.

If 120vac is not present at the switch make sure the electric switch for the water heater in the control panel is on. If so, you will need to find the relay box that the 12vdc blue light operates, probably behind the front of the WH (on the outside). That relay is what activates the 120vac to the next rocker switch on the exterior of the WH. See where you are.

[KBMKVIII]

Thank you everyone for helping me out, I greatly appreciate it!
I got home late after another few loads out of the house, so no model info.
Got a hot shower there!
It’s been quite a day.
I will be looking into all the information given above tomorrow.
I’ll update asap.

[RollaMo]

Originally Posted by bobbecky

I'm guessing this is a Suburban water heater. If so, outside behind the water heater cover, at the lower left corner there is a small rocker switch.

It may be switched off and be aware that the switch is always installed upside down from what you would normally expect it to be positioned. It turns on the 120 volt power to to the electric side of the water heater.

Just as an FYI
Our new 2022 Cougar with Suburban gas/electric water heater does not have the outside rocker power switch.
It is turned on/off using the In Command display panel (either in the RV or on app on your phone).


Is the absence of the outside switch due to the new ones having In Command?


I got around to de-winterizing the RV today, and I looked for that outside rocker switch but it just does not have one anywhere.
Turning the water heater on via the In Command, I can choose gas, electric or both.
I tested all three ways today and everything works.


Just thought it was strange that it didn't have that outside power switch.

[sourdough]

Originally Posted by RollaMo

Just as an FYI
Our new 2022 Cougar with Suburban gas/electric water heater does not have the outside rocker power switch.
It is turned on/off using the In Command display panel (either in the RV or on app on your phone).


Is the absence of the outside switch due to the new ones having In Command?


I got around to de-winterizing the RV today, and I looked for that outside rocker switch but it just does not have one anywhere.
Turning the water heater on via the In Command, I can choose gas, electric or both.
I tested all three ways today and everything works.


Just thought it was strange that it didn't have that outside power switch.

From what I've read/seen that external rocker switch used to not be there. Then they added it, for what reason I've yet to ascertain. I suspect it's very possible that the switch is no longer there as it really served no purpose IMO other than to complicate things and add a relay box on the WH to fail. I am not familiar with In Command as I wouldn't buy an RV with it when I bought this one. The issue may be with that and somebody can probably chime in to assist with it if so.

[KBMKVIII]

Turns out the electric element is bad.
Ohms OL.
And it’s a suburban 12 gal.
Ended up switching to gas and all is well.
The red light was going on because when flipped the switch, the flame was not on yet.
I gave it about eight seconds and the gas portion of the water heater came on for the first time with no issues.
Going to Home Depot tomorrow after work to pick up a new element!
Y’all have been extremely helpful, thank you!

[JRTJH]

Originally Posted by KBMKVIII

Turns out the electric element is bad.
Ohms OL.
And it’s a suburban 12 gal.
Ended up switching to gas and all is well.
The red light was going on because when flipped the switch, the flame was not on yet.
I gave it about eight seconds and the gas portion of the water heater came on for the first time with no issues.
Going to Home Depot tomorrow after work to pick up a new element!
Y’all have been extremely helpful, thank you!

Make sure you buy a 120 VAC element... There are elements that same size that are 120 VAC and 240 VAC... The 240 won't get hot enough to heat your water for "days on end"... LOL

[bobbecky]

Also, make sure the element you get is a screw in type element. You also might need the wrench for it, as the hex is very shallow and hard to get a wrench on.
https://www.amazon.com/Suburban-5209...e%2C251&sr=1-2

https://www.amazon.com/Camco-Residen...e%2C251&sr=1-6

[KBMKVIII]

Originally Posted by JRTJH

Make sure you buy a 120 VAC element... There are elements that same size that are 120 VAC and 240 VAC... The 240 won't get hot enough to heat your water for "days on end"... LOL

I’ll make sure!
Thank you!

[KBMKVIII]

Originally Posted by bobbecky

Also, make sure the element you get is a screw in type element. You also might need the wrench for it, as the hex is very shallow and hard to get a wrench on.
https://www.amazon.com/Suburban-5209...e%2C251&sr=1-2

https://www.amazon.com/Camco-Residen...e%2C251&sr=1-6

This is great info.
Thank you