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Unicorn III Internal Water Tank Changeover Valve Wiring

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I have seen a few posts around about people putting a solenoid valve in place of the manual changeover valve to make it easier to fill the onboard tank. I thought i would try and improve on this slightly by add a low water indicator and a high water indicator - However, i just wanted to check my wiring makes sense and none of the other posts covered off any wiring that was similar and if it is correct may well help others that are thinking about this.


The only time i would want to use the solenoid and the level indicators is when i decide to use the internal tank (Far various reasons i didn't want to go down the road of putting in a full tank level). This is why i have included a main switch at the start. That way, there is no chance of operating the solenoid or the indicator lamps lighting up when not in use.


The idea is once the main switch is on, i can keep the pump switch by the door to external and just use the second switch to open the solenoid to fill the internal tank. Once the tank is full the blue indicator light would come on (i know it should hold one aqua roll's worth of water so could do away with having this light but i wanted this there as i use a 50l water hog normally and just keep the internal tank topped off so it is easier this way to know when it is full without having to look/listen for water overflowing) and then i can just turn the solenoid switch off and set the main pump switch from EXT to INT.

As the level goes down the blue indicator would turn off and then when i am down to about 15% left in the tank, the red indicator light would display as a warning to then top off the tank again.


If you could let me know if i have gone wrong or if this looks right please.



Water Tank Wiring.jpg

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Hi  Been a few posts on  this topic on here.  Your solution with the LEDs should work OK but like many there is an option to put a level meter in with bezel matching the other gear.  For example https://www.marcleleisure.co.uk/cbe-fresh-waste-water-level-indicator-kit-grey.html?gclid=Cj0KCQjwpZT5BRCdARIsAGEX0zmoFB_GWEsoESLV2zCM6Yjw7S54fUpRbjdQBS5XcbINxO8k7zsw3U4aAk1cEALw_wcB

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Hi Kts,


Welcome to the Forum.


Your circuit is OK and will work.  I have attached a PDF of a slight mod to your circuit.  The only difference is the solenoid switch is now fed from the other switch instead of in parallel with it. 








Edited by TintentTerry
modify drawing
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I've been a long time lurker :ph34r:


@TintentTerry - Ah yep good pointer on that diagram as that is what i wanted to do with having having the solenoid only live only when the first switch was on rather than have it live all the time like in my original diagram.

I notice you added a negative feed from the Solenoid around to the warning lamps - would this be necessary? It just that the Solenoid is in a different direction as to where the other wiring would be and i was thinking it would have been easier for me to just have one cable run on it's own to the solenoid.

I have revised the drawing to include your change, but if i were to bring back all the negatives to the first switch like i have shown. That would still working wouldn't it for a complete circuit?


I think i mentioned in my first post. For various reasons i didn't want to install the dedicated water gauge that you can get but thanks for the linky as other may be interested in this.

Water Tank Wiring V2.JPG

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I only  loop in and out so that that a piggy back spade connector can be used, which cuts out the need for extra joints in the wiring.  There's no problem doing it the way you  want to though. 

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