Replacing Water Heater

Mtnkat13

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Joined
Jul 17, 2024
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I have a 2017 Vintage Cruiser and am replacing the tanked water heater with a tankless water heater. The new water heater has a gas line input, cold water input, hot water output and 4 wires. Two for the electric and 2 for the controller. See pic attached. I have 2 questions.

1) What is the switch above the one labeled "water heater"?

2) What is the blue wire connected to in the attached pic? I only have the 4 wires I listed above and not sure what to do with this extra wire from the old tank?

Sorry the pics are sideways. :/

Any help is appreciated. Thanks.
 

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Hello
The Blue wires are for controller to operate the settings on the tankless, the switch should be what is a pilot cut powered by 12v you should use that to power the 12v on the tankless black and white wires. I can not make out the other switch you are asking about. But remember do not power the tankless with 120v! It's 12v signal and lp only. On my old dual fuel heater I used the extra 120 volt circuit for more basement power if needed so I didn't have to abandon the circuit. It's is a pretty straight forward install..
I ABSOLUTELY love mine!

LIFE IS GOOD!!!! LIVING IT!!!!

2005 41'4 ATRIUM SE CAT
2017 20' Diamond closed trailer
2017 Streetglide Special
2010 Mini Cooper or 04 H2
 
Thanks for you reply, it is appreciated as I am new to all of this. I did find out the other switch is for the lights, lol.

I know the blue wires on the tankless system are for the controller. I am asking about the blue wire that was hooked up to the original Sullivan water heater. Can I just cap that one since I am not using it? I tried doing more research and think it is a "fault" wire, but not 100% sure.
 
You have me thinking now, so wanted to hopefully clarify a bit more.

The Sullivan tank Water heater has the switch that I showed in the pics. It has a green, orange, blue and purple wires to it. I believe these are to power the water heater from the old switch. There is then also a white and black wire (with a ground) to hook up the power to the old water heater.

The new tankless water heater has 4 wires on it, two blue and one black, and one white one.

In watching all the videos, it appears the two blue wires get attached to the new controller (which is digital). Then I attach the white wire from the RV to the white wire on the new tankless heater. Then do the same for the black wire.

I guess my question are...
Can I just remove the orange, purple and green wires now that the old switch isn't attached to anything and cap then just cap the old blue wire?

Where should I attach the ground wire the is grouped with the white and black power wires?

Hope that make more sense.

I really appreciate your help.
 
Ok the old wires are from the polit cut, you only need 12v black and white to power your unit, the other extra wires you can cap as mentioned, they are for when the pilot lites it sends a signal back the the panel so you know the heater actually turned on. Test your 12v to make sure the colors of the wires are correct, I have seen red in the past as being the hot wire not the black one, white or green should be ground or neutral. I've also seen an orange wire in the past. Different manufacturers use different colors sometimes..

It's funny I was thinking for the other switch just being a compartment light but didn't mention it.
Hope this helps a little more sorry as I am supposed to be at work...opps!!

LIFE IS GOOD!!!! LIVING IT!!!!

2005 41'4 ATRIUM SE CAT
2017 20' Diamond closed trailer
2014 Streetglide Special
2010 Mini Cooper or 04 H2
 
Ok. The voltage of the white and black wires that were connected to the old heater are definitely 120V.

The other 4 wires I talked about have no voltage readin when I test them in any configuration. And 3 of them only connected to the old water heater. Only the blue wire goes somewhere into the camper.


So annoyed with the videos that said just attach these 4 wires and "boom" done. Lol

What are my next steps? Do I need to purchase a converter to bring it down to 12V? It is the only set of wires that are not going to anything else. All the others appear to be for the tail lights and the lights on the bathroom.

So something like this:
https://www.voltlighting.com/inline...k8vM3_oSsZFlh_16lmGiHesKLTrBgJFQaArohEALw_wcB
 
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It is really that simple! Only use the ones coming from the old switch inside the coach! And make sure it is in the on position before testing for 12v!; once you have found 12v your heater will be powered up but will not start until it detects water flow..don't let it get to you just keep testing the way you are and it will work out. If the old heater worked then the power was and is still there...take a step back breath and attack it again..my only question is was the old water heater 120v and propane? Or 120v only! But that would be unusual
 
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I finally got it up and running. Was not as easy as the videos show it to be, but I did it. Thank you again for all your help. :)
 
I do it everyday so to me yes it is an easier task. But I am curious as to what was the problem finding your 12v and how you got power to the new unit. 12v can come from anywhere technically. Flow is what triggers the system to fire.
Great to hear you got it as I knew you could. I can't! Should not be in our vocabulary! It may take a few trys but that's how it goes..
 
I had a 120V connection from the old water heater and ended up putting a converter onto it so it brought the output down to12V. It won't just run on the battery and propane, but I have solar power on the RV and it is working great with that. I was not able to find any wiring that was coming from the battery to connect directly so used what I had.
 
If you plugin and disconnect battery and lights work, you already have a CONVERTER TO GIVE YOU 12VDC and charge battery. You should alreayd have the 12vdc at the WH location, IF YOU TURN ON THE WH SWITCH?
 

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