Water Tank overflow when on city water

[tncorbiere]

Everytime we have camper we have been on city water with no issues. So for the first time we filled out water tank and used it while camping. I noticed that the water pump would turn on about every three minutes. After we went through a full tank of water I switched back to city water. Over night my city water filled my water tank. I switched on the water pump and ran some water down. Then switched it off. I was then able to watch the tank fill back up and over flow. Obviously there is a back fill problem but is it a check valve that can be reset or chamged? Trailer is not even 6 months old and am hoping it's not the pump.

[RickV]

Originally Posted by tncorbiere

Everytime we have camper we have been on city water with no issues. So for the first time we filled out water tank and used it while camping. I noticed that the water pump would turn on about every three minutes. After we went through a full tank of water I switched back to city water. Over night my city water filled my water tank. I switched on the water pump and ran some water down. Then switched it off. I was then able to watch the tank fill back up and over flow. Obviously there is a back fill problem but is it a check valve that can be reset or chamged? Trailer is not even 6 months old and am hoping it's not the pump.

I had that problem once about 5 years ago. In my cause what had happened was I had left the pump on when I switched to city water and when I turned off the pump the pressure from the city water kept the check valve open so it back filled into the tank. Try turning off the city water, then turn your pump on run some water from a tap, then turn it back off again then turn the city water back on.

[tncorbiere]

Thanks! I will try that later today and give an update

[ChuckS]

Water pump has an internal check valve .. if the recommended steps previously posted dont fix it then pull it out and either replace it or take apart and look at the seal .. there is also a repair seal kit available if Shurflo pump

Also.. to prevent backfilling thru the water pump in the future place a check valve on the output side of the water pump that will prevent city water from bypassing that internal check valve and over filling your fresh water tank

https://www.homedepot.com/p/Watts-1-...-SCV/203804502

check your water pump line fittings prior to purchase to be sure this will wokr for your install

Short PDF I wrote that should help you understand the issue better.. links inside the PDF for internal valve repair kit if needed... you may not need .. maybe just a piece of crap stuck in that valve

[RickV]

Originally Posted by ChuckS

Water pump has an internal check valve .. if the recommended steps previously posted dont fix it then pull it out and either replace it or take apart and look at the seal .. there is also a repair seal kit available if Shurflo pump

Also.. to prevent backfilling thru the water pump in the future place a check valve on the output side of the water pump that will prevent city water from bypassing that internal check valve and over filling your fresh water tank

https://www.homedepot.com/p/Watts-1-...-SCV/203804502

check your water pump line fittings prior to purchase to be sure this will wokr for your install

Short PDF I wrote that should help you understand the issue better.. links inside the PDF for internal valve repair kit if needed... you may not need .. maybe just a piece of crap stuck in that valve

Will putting a secondary check valve affect water pressure from the water pump?

[ChuckS]

Originally Posted by RickV

Will putting a secondary check valve affect water pressure from the water pump?

Not in the least bit what so ever.... Also some folks have put the check valve on the suction side coming from the fresh water tank...

This will serve same purpose...

The key to the check valve is look at the direction of the arrow on the check valve and make sure that the end you install on matches the "normal" direction of flow otherwise you wont get any water from the water pump

[ChuckS]

If you place a check valve on the water pump output side make sure the check valve you buy has the correct flow direction

The first image is the correct flow direction and will work great

The second image is same valve but flow arrow is reversed... if you install this one on your pump output you will get no water from water pump

[JRTJH]

Most Cougar trailers have a FloJet water pump, not a ShurFlo pump. They perform the same function, but are not "readily interchangeable" because the terminal fittings for FloJet pumps use an O-ring/locking lever and ShurFlo uses threaded connectors. To change to a different brand pump, you'll need to also change out the pump connection fittings on the trailer plumbing lines.

That said, I'd suspect your pump is a FloJet. The internal pump head diaphragm serves as the check valve. Any debris or trash that gets into the pump head will prevent the diaphragm from sealing well and will cause "backflow into the fresh water tank" when connected to city water. You'll also hear the water pump cycle off/on/off when on internal tank water because as the water "bleeds back through the pump head" the pressure goes down causing the pump pressure switch to activate to raise the water pressure.

During trailer assembly, any sawdust or plastic drill shards that fall into the fresh water tank can/will get drawn up the supply hose and get trapped in the pump head. That will cause exactly what you're experiencing.

Taking the pump apart to clean out the trash is an easy project for most people. Just pay attention to how you take it apart so you can reassemble it the same way. MISSING A STEP CAN CAUSE THE PUMP FAILURE... and you do not want "extra parts when the job is done".....

The way to prevent this kind of failure is to install a "water strainer" in the supply line from the pump. They are available for FloJet and ShurFlo pumps and are not interchangeable.

This is a photo of the FloJet strainer. They are available at Amazon for less than $10 and are one of the "first modifications" I'd recommend for anyone buying a travel trailer. The strainer is serviceable, so every year, remove the screen and clean it. https://www.amazon.com/Flojet-017403...s%2C214&sr=8-3

[bobbecky]

DO NOT install a check valve on the suction side of the pump. Did that and you end up blowing water from the suction side fittings. I removed the suction side check valve and then installed one on the pressure side and no more issues.
The check valve is in the center of the photo, on the PEX line above the pump.