City water question from a rookie

stew0720

Member
Hello all. I'm a 5er rookie who just got a Bighorn 3970RD. I've read the Water supplement from the HOM, and it's great info!! I still have just a few questions. Apologies in advance if this is in the wrong forum.

Does the water pump interact with the city water from hose at all? I'm currently at my deer lease, where we have well water with poor water pressure. For showers and other items where we need good pressure, i've filled the tank and i use the water pump. After filling the tank, set the valve back to normal where it is now. I'm assuming when the pump is on, it's drawing only from the tank. When pump is off, it's not pulling from tank, but taking straight from city water line correct? If the tank becomes empty and the pump is on, will it burn the motor? I basically turn the pump on and off only when i need good pressure, as to not drain the tank.

I'm rambling, so i'll sum up my question to see if i have it right:

Does the water pump interact with the city water line at all, or just pump straight from the filled tank?
Tank Full, Valve set to Normal (City water) with hose on, Pump OFF: takes from city water only (doesn't draw from tank at all?)
Tank Full, Valve set to Normal (City water) with hose on, Pump ON: draws from tank only, no city water interaction?
If pump is on and tank runs empty, will it immediately burn motor or does it know to shut off?

Also: how often do you guys flush the black water tank?

thanks in advance!
 
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TxCowboy

Well-known member
Here's my understanding on your questions:

Does the water pump interact with the city water line at all, or just pump straight from the filled tank?

Filled tank only.


Tank Full, Valve set to Normal (City water) with hose on, Pump OFF: takes from city water only (doesn't draw from tank at all?)

Correct. The system relies on the water pressure provided by the city/rv park/well/ etc. No water is pulled from the fresh water tank. BTW, the Normal setting plus city water will work even if the fresh water tank is empty. I know people that have never had water in their fresh water tank except when they did the PDI to test the DC water pump.


Tank Full, Valve set to Normal (City water) with hose on, Pump ON: draws from tank only, no city water interaction?

Correct. Pulls from the tank only.


If pump is on and tank runs empty, will it immediately burn motor or does it know to shut off?

Having the pump on and no water in the fresh water tank can damage the pump. I do not believe there is a sensor that shuts down the pump if there is no water in the fresh water tank.


Also: how often do you guys flush the black water tank?

The short answer is: as needed. We flush ours every couple of weeks since we're long term at a park. Otherwise, we'd dump it prior to departing and refill with a small amount of water and chemicals so that it mixes well and helps clean the interior of the black tanks when we're moving.

HTH!
 

danemayer

Well-known member
Let's start over.

With respect to the 4-way Anderson Valve settings:

"NORMAL" is the position used in conjunction with the pump to use the fresh tank as your water supply. In this position, it doesn't matter if you're connected to city water. The city water doesn't get through the 4-way valve. The only water you can get is from the fresh tank, and only if the pump is ON.

"CITY" is the position used to route city water (campground faucet) to the RV water fixtures. However, in the "CITY" position, a channel is also open to allow you to pump water from the fresh tank, if the pump is on.

So, I'd suggest you leave the 4-way valve on "CITY" all the time, unless you're filling the fresh tank. When you want higher water flow, say for a shower, turn the pump ON. When finished, turn the pump OFF.

If the pump is left on all the time, when the fresh tank runs dry, you may notice that the water flow is less. That would definitely be a signal to turn the pump OFF.

With the pump ON, and water in the fresh tank, when you open a faucet, the pressure in the line, at the pump, drops, signaling the pump to start running. When you close the faucet, the pressure in the line builds and the pump shuts stops running. However, if you run the fresh tank dry, when you close the faucet, line pressure may or may not build up enough for the pump to stop running. Eventually the pump may be damaged. I doubt damage would occur in a few minutes.

If you fill your fresh tank, and use the pump only when taking showers, you'll get a feel for how frequently you have to refill the fresh tank to avoid running the tank dry.
 
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