Use the water pump with no water in tank?

[jmart273]

I am currently hooked up to city water.

In order for me to enjoy a shower with any type of water pressure, I turn on my water pump to give an extra boost. I started doing this after receiving the tip from this page.

I have always had water in my fresh water tank, and make sure it is somewhat full before using the pump.

My question is this: do I have to have water in the fresh water tank, for the pump to pump? Will it act as an inline booster pump for the water coming from the city connection?

I am tired of filling up the tank, but don't want to burn up the motor.

[chuckster57]

The city water is connected AFTER the water pump, and if your fresh tank is empty your running the pump DRY.

I've never read any tip here that suggested running the pump for increased pressure.

[TheRealMacGyver]

From what I understand the pump can run dry without harming it. I don't think I would want to test that though! I never tried what you are saying, but I have removed the pressure regulator at some sites to resolve low pressure. Not sure if you are using one. Overall shower pressure is low for my liking!

[sourdough]

If you are hooked up to city water and you feel you have to turn on the pump to augment pressure....something is wrong. Either you have a pressure reducer in line that you don't need or the city water pressure (rv park) is low. I don't know where you heard of turning on the pump to increase city water pressure (I've never heard it) but I wouldn't. Buy a new shower head that increases pressure.

[Alpine]

Howdie.... This will take all the guessing out of the equation. And do get this "adjustable" one!


https://www.walmart.com/ip/Camco-400...ator/55635375?

[JRTJH]

OK, let's do a little "hydraulic pressure" lesson: First, the water pump will only "add to the pressure" of the city water system IF there is water for the pump to pressurize. The pump draws its water supply from the fresh water tank, not the city water system, so if the tank is empty, the water pump can't increase pressure in the trailer lines.

On the other side of that coin, if the water pump is capable of supplying 50 PSI and the city water is coming into the trailer at (let's say) 30 PSI, then turning on the water pump would draw water from the fresh water tank and provide it to the water system by pressurizing the system to the water pump's maximum of 50 PSI. So, yes, the water pump "can" increase or augment the city water connection, but only if the pump setting is greater than the city water pressure setting. That's where the "if you're using a pressure regulator" comes into play. If you have a "cheap pressure regulator" (most are factory set at 35 or 40 PSI) and it's either calcified, rusted or otherwise "not fully functional" chances are good that you're only getting minimal flow through that regulator. So turning on the water pump (provided it has water in the fresh water tank to draw) will supply additional water to the trailer system up to the pressure setting of the water pump.

It's sort of like filling a bath tub with water. If you turn on the faucet it will fill at a specific rate. If you also run a hose through the back door and turn it on, you'll get more water into the tub and it will fill faster. The same applies to your trailer water supply. In this example, the city water is your bath tub faucet and the water pump is the "hose through the back door".....

All FloJet and Shurflo pumps used in RV applications are 'run dry" type pumps. That means they can be "run without input water" for a short time. How long they will run before overheating and/or damaging the pump head is not stated, but be assured they are not capable of running indefinitely without damage. A minute or two is much different than leaving it on for an hour or so because you forgot and was busy doing something else. If that case, you're very likely to need a replacement pump........

[captcolour]

Originally Posted by Alpine

Howdie.... This will take all the guessing out of the equation. And do get this "adjustable" one!


https://www.walmart.com/ip/Camco-400...ator/55635375?

+1 That's what I use. Takes the guess work out of the in coming pressure.

Wonder if they work on units other than Alpines

[Ruko]

Do you have it switched to tank fill instead of city water? If you have it on tank fill it is only filling the fresh water tank and would then need the pump on to pressurize the water system.

[jmart273]

Originally Posted by JRTJH

OK, let's do a little "hydraulic pressure" lesson: First, the water pump will only "add to the pressure" of the city water system IF there is water for the pump to pressurize. The pump draws its water supply from the fresh water tank, not the city water system, so if the tank is empty, the water pump can't increase pressure in the trailer lines.

On the other side of that coin, if the water pump is capable of supplying 50 PSI and the city water is coming into the trailer at (let's say) 30 PSI, then turning on the water pump would draw water from the fresh water tank and provide it to the water system by pressurizing the system to the water pump's maximum of 50 PSI. So, yes, the water pump "can" increase or augment the city water connection, but only if the pump setting is greater than the city water pressure setting. That's where the "if you're using a pressure regulator" comes into play. If you have a "cheap pressure regulator" (most are factory set at 35 or 40 PSI) and it's either calcified, rusted or otherwise "not fully functional" chances are good that you're only getting minimal flow through that regulator. So turning on the water pump (provided it has water in the fresh water tank to draw) will supply additional water to the trailer system up to the pressure setting of the water pump.

It's sort of like filling a bath tub with water. If you turn on the faucet it will fill at a specific rate. If you also run a hose through the back door and turn it on, you'll get more water into the tub and it will fill faster. The same applies to your trailer water supply. In this example, the city water is your bath tub faucet and the water pump is the "hose through the back door".....

All FloJet and Shurflo pumps used in RV applications are 'run dry" type pumps. That means they can be "run without input water" for a short time. How long they will run before overheating and/or damaging the pump head is not stated, but be assured they are not capable of running indefinitely without damage. A minute or two is much different than leaving it on for an hour or so because you forgot and was busy doing something else. If that case, you're very likely to need a replacement pump........

Thanks for the lesson. I didn't know if it would just act as a booster pump or not.

[jmart273]

Originally Posted by Alpine

Howdie.... This will take all the guessing out of the equation. And do get this "adjustable" one!


https://www.walmart.com/ip/Camco-400...ator/55635375?

Thanks Alpine! I will definitely be getting one of these. What pressure do you run it at?

[jmart273]

Originally Posted by Ruko

Do you have it switched to tank fill instead of city water? If you have it on tank fill it is only filling the fresh water tank and would then need the pump on to pressurize the water system.

Mine isn't that fancy. One hole for tank fill, another for city connection, another for black tank flush.

[jmart273]

Originally Posted by chuckster57

The city water is connected AFTER the water pump, and if your fresh tank is empty your running the pump DRY.

I've never read any tip here that suggested running the pump for increased pressure.

Let me find the thread for my original "water pressure sucks" post. It definitely works, and was a great tip so I didn't have to buy a new shower head. City water + water pump is more pressure than just city water, or just fresh water tank and pump.

I wanted to just take off my pressure regulator but everyone told me not to.

[jmart273]

Originally Posted by TheRealMacGyver

From what I understand the pump can run dry without harming it. I don't think I would want to test that though! I never tried what you are saying, but I have removed the pressure regulator at some sites to resolve low pressure. Not sure if you are using one. Overall shower pressure is low for my liking!

Mine is always so low that you couldn't stand in the shower and have it spray on you. It would just trickle straight down. I didn't want to buy a new shower head. Now, with the pump running, it provides adequate pressure.

[Johnny's Journey]

Originally Posted by jmart273

Thanks for the lesson. I didn't know if it would just act as a booster pump or not.

[jmart273]

Originally Posted by Johnny's Journey

Am I missing something? I understand booster pumps. They are used extensively in several industries and applications, some of which I am quite familiar with. I also know it acting as one would be a stretch based on the supply from the city, not a separate tank or type of supply.

I was simply asking a simple question, mainly because I cannot find a plumbing diagram for my rig.

[Johnny's Journey]

Originally Posted by jmart273

Am I missing something?

Have you located your water pump and how it's plumbed ? As mentioned, you are more than likely pulling water from your fresh water tank even though your fresh water city water is hooked up and water is on. That's the education you need to verify. None of us here can see your unit. Only you can.

[jmart273]

Originally Posted by Johnny's Journey

Have you located your water pump and how it's plumbed ? As mentioned, you are more than likely pulling water from your fresh water tank even though your fresh water city water is hooked up and water is on. That's the education you need to verify. None of us here can see your unit. Only you can.

I have, but haven't paid much attention to how it is plumbed. Sounds like it won't work as I had hoped. Next time I take it out (3 weeks) I will take a closer look. Regardless, I am going to purchase a higher quality, adjustable water pressure regulator and see if that fixes my low pressure problem. When I'm hooked to city water I shouldn't have to run the water pump to take a shower.

[Johnny's Journey]

Originally Posted by jmart273

Next time I take it out (3 weeks) I will take a closer look.

Awesome !

[Johnny's Journey]

If all checks out OK with your plumbing and pressure testing and you still have issues watch this video. Pay close attention @ around the 2 minute mark. Your going to see a check valve within the city water inlet. Look into that as well.

https://www.youtube.com/watch?v=k7xeHFOZOBs