Water Pump Switch

[roadtrip07]

Hi All,
I just finished putting in new wiring on my 63 Bambi. I was looking at some other people's threads/pictures, and I've noticed that some people have on/off switches for their water pumps. I will be getting to the plumbing soon, and I am wondering, is this necessary? What are the purpose of those switches...i.e, wouldn't the pump operate when it's supposed to without a switch? Thanks.

[blmitch5]

You need to turn it off when using city water and when you leave the trailer. If you have a leak it will keep running to pressurize the lines and you could loose a lot of water etc.

[Minno]

Also, when the tank is empty, or you're traveling down the road, you need to be able turn the pump off.

[HowieE]

Yes you want to be able to turn the pump off as noted above.

You will want to be able to switch the pump on and off when pumping antifreeze into the system.

You may also notice that a lot of trailers have 2 switches. One in the bathroom and one in the kitchen area. This is most helpful when on the road and you just need one or the other facility. If you consider this keep in mind that these switches are single pole double through.

[roadtrip07]

thanks for the answers. i did notice, however, that a water pump i was looking at online advertised itself as being able to run dry without damage.

[Minno]

I'll betcha that the installation instructions call for an on/off switch to power the pump. Running dry without damage vs. running constantly with nothing to pump but air 'cuz you can't shut it off are two different things. RV water pumps will pump until their set pressure is reached in the water line, then they shut off. You open a faucet, that lowers the pressure in the line, and that in turn triggers the pump to kick in and provide more water. With just air, there will be no pressure build-up in the water line, and the pump will run constantly. Not good.

Chris

[pmclemore]

Sometimes, while you are traveling, a faucet will jolt itself to the on position. If your water pump is running then you will pump yourself dry; if your sink is plugged, you will have an unpleasant mess awaiting you when you open your door.

Pat

[HowieE]

It is not a question of whether or not you need a switch it is just a question of how many and where to put them.

[roadtrip07]

if a water pump was the only thing on a circuit, could the breaker theoretically serve the same purpose as a switch?

[Minno]

You'd need a 12 volt breaker then. Most of the 12 volt panels I've seen are fuses, not breakers. In theory, a breaker would work, although it may not be in the best location from an ease of use point of view.

You certainly have my curiously up though. Why are you against installing a switch for the water pump? Enquiring minds and all…

Chris

[Dr Dan]

I picked up a timer switch yesterday to replace the on/of pump switch. Does anyone have any comments on that. Knowing you should turn off the pump before hitting the road and actually getting it done are two different things in my life these days. On my last trip I returned home to hear the running of the water pump. Don't know how many hours it was going. That's when I got the timer idea. Have one on the Iron switch at home. Got tired of screwing up that "night out" with my wife to go home and see if she unplugged the iron. Does anyone see a problem with a timer instead of a switch ?

[Minno]

I don't. I was actually thinking of getting a timer for the water heater since that's what we seem to forget to turn off. The pump switch is illuminated, so we see it on when we lock up to travel, but the water heater switch isn't. Is the timer you picked up battery operated, or a manual one? Just wondering.

[Pahaska]

It is easy to put LEDs on both the water pump and the water heater switches. Radio Shack has 12v LEDs with the resistor built in at reasonable prices.

I have LEDs on water heater, water pump, and outside light switches. My wife is responsible for inside preparation for towing. She just needs to turn off all of the green lights.

[Dr Dan]

I just purchased a 60 minute timer switch at lowes that fits in a switch box, twist the dial to how ever many minutes you think you will need water and listen to it click. I wasn't thinking about it being 12 volt and don't know if it would work, but assume it will. I'll let you know

[Sky]

Originally Posted by Pahaska

..... Radio Shack has 12v LEDs with the resistor built in at reasonable prices.

Don't mean to hijack this thread, but guess I am. What do you mean
"with resistor built in"? I just ordered a 12v green led for a water-pump-ON
indicator. I was planning to hook it in parallel where the 12v power line enters
the pump. Whats this resistor stuff?

[Pahaska]

Originally Posted by Sky

Don't mean to hijack this thread, but guess I am. What do you mean
"with resistor built in"? I just ordered a 12v green led for a water-pump-ON
indicator. I was planning to hook it in parallel where the 12v power line enters
the pump. Whats this resistor stuff?

LEDs are available with or without a built-in dropping resistor. If you hook one without a resistor directly to 12V, you get exactly one very bright, but very, very short burst of light. The Radio Shack LEDs have the resistor built in so that you can tie them in to any 12V circuit without any other component required.

I have some LEDs without resistors as telltales for other switches in my trailer. For each of these LEDs, I used a resistor from my parts box to limit the current.

[Jim Foster]

Switches that light up when "on" can be purchased in various colors at most auto parts stores. Most are "rocker" switches, which are nearly flush when installed.

[Pahaska]

Originally Posted by Jim Foster

Switches that light up when "on" can be purchased in various colors at most auto parts stores. Most are "rocker" switches, which are nearly flush when installed.

They work fine, but it is better to use the existing switch with a LED whenever possible. Both of my water pump switches, for example, are integrated with other switches or built into my monitor panel.

Also, the water pump in most models is controlled by a 3-way circuit with switches in the bathroom and galley. The LED must be installed at the pump or after the last 3-way switch. Mine is installed on the monitor panel which is the last switch in the circuit.