Check valve location—before or after pump

[chaps2018]

Having had the fresh water tank overfill issue (usually fixed by relieving pressure on the valves, cycling the valves then reconnecting the city water). I recently had a new issue.

Thanks to Indiana State Parks, I had two occasions recently to use my freshwater tank for 2x week long stays.

Never having his issue before while on pump/fresh water tank usage, i had two symptoms: 1)my fresh water pump cycled periodically., 2)When the pump was OFF i noticed the plumbing did not hold pressure like it used to a year ago.

I ripped the basement apart and checked nearly all the fittings/fixtures to ensure I didn’t have any leaks. The only one I didn’t check was the shower fixture.

I also ensured I bled the washer/dryer connections to ensure the pump wasn’t pushing against air in the lines.

The Sureflo manual indicates the pump will cycle periodically if there is scale buildup on the check valve inside the pump.

At this point I assumed the pressurized size of the plumbing was leaking back into the fresh water tank. That would explain both symptoms above given i had checked for leaks.

I could take the pump apart and clean/replace the check valve or just add threaded check valve Camco 23303 1/2" Back-Flow Preventer - Lead Free https://www.amazon.com/dp/B000EDUTN6..._pGgQDb01P973D

In looking through previous posts on this subject I see a mix of some put it before the strainer and some after the pump. While the 2nd symptom above would be solved, seems to me if it was after the pump the pump would continue to periodically cycle since the pump’s check valve would continue to leak.

On the other hand, some posters say when installed before the strainer they can not get water flow as the check valve constrains the supply plumbing too much.

Any experiences to share from you folks who have installed the separate check valve?

[fonzie]

Add check valve between water pump and strainer on the intake side.

http://www.forestriverforums.com/for...mp-162060.html

[chaps2018]

Thanks for posting that thread. That OP found the problem I had mentioned above.

I will install it between the strainer and pump.

[5picker]

I've installed two. One on the suction side, one on the discharge side.
I agree with fonzie... BETWEEN the pump and suction/strainer was the better option.

When installing a check on the suction side I like to protect the suction/strainer from pressure. I don't really know how much 'pressure' they can take as they are obviously designed for the suction side.

While the pump's internal check valve is more on the discharge side of the pump head, I believe the pump itself can withstand the city water pressure regardless. And also as mentioned, if the check is on the discharge side, it can allow the pump to leak pressure and continually cycle. I also believe on the one I placed on the discharge side restricted flow to a degree.

[Mac549]

Originally Posted by chaps2018

Having had the fresh water tank overfill issue (usually fixed by relieving pressure on the valves, cycling the valves then reconnecting the city water). I recently had a new issue.

Thanks to Indiana State Parks, I had two occasions recently to use my freshwater tank for 2x week long stays.

Never having his issue before while on pump/fresh water tank usage, i had two symptoms: 1)my fresh water pump cycled periodically., 2)When the pump was OFF i noticed the plumbing did not hold pressure like it used to a year ago.

I ripped the basement apart and checked nearly all the fittings/fixtures to ensure I didn’t have any leaks. The only one I didn’t check was the shower fixture.

I also ensured I bled the washer/dryer connections to ensure the pump wasn’t pushing against air in the lines.

The Sureflo manual indicates the pump will cycle periodically if there is scale buildup on the check valve inside the pump.

At this point I assumed the pressurized size of the plumbing was leaking back into the fresh water tank. That would explain both symptoms above given i had checked for leaks.

I could take the pump apart and clean/replace the check valve or just add threaded check valve Camco 23303 1/2" Back-Flow Preventer - Lead Free https://www.amazon.com/dp/B000EDUTN6..._pGgQDb01P973D

In looking through previous posts on this subject I see a mix of some put it before the strainer and some after the pump. While the 2nd symptom above would be solved, seems to me if it was after the pump the pump would continue to periodically cycle since the pump’s check valve would continue to leak.

On the other hand, some posters say when installed before the strainer they can not get water flow as the check valve constrains the supply plumbing too much.

Any experiences to share from you folks who have installed the separate check valve?

Check valves should be located on the discharge side of the pump. Most RV pumps are diaphragm type pumps and do not require check valves unless the piping downstream of the pump cross ties with some other system that may create a back pressure situation. External check valves are usually installed on impeller type pumps to prevent loss of water or unnecessary head pressure at the impeller. Strainers should be installed on the suction side of the pump to prevent debris from entering the pump.

[RStormC]

I origin put mine before the pump. The pump did not work properly. Moved it to the output side and haven't had a problem since.

[Mac549]

Originally Posted by RStormC

I origin put mine before the pump. The pump did not work properly. Moved it to the output side and haven't had a problem since.

Check valve?