Water Pump Issue

[truk4u]

I have two Shurflo's hooked in tandem, one is the older smaller model and the other is the newer 5.7 and I have an accumulator tank. My ex CC, now Jamies, had two small Shurflo's and also an accumulator tank.

[Jon Wehrenberg]

Jon, while reading some of your responses, I am wondering about the accumulator tank I use to have but was removed when I got my SurFlo Extreme pump installed. (Directions said to remove any accumulator tank from the system) All works very well, about 55 to 60psi but what about expansion in my system. What are your thoughts?
Thanks

I am not familiar with all the systems out there, or the various pump manufacturers, or how they handle expansion. I do know that if there is no "head" of air pressure the system functions more like a hydraulic system in that as soon as water is drawn the system pressure goes from 55 to 0 almost instantly. Obviously a switch senses that and a pump responds, but most systems I have seen either have an external accumulator or there is one that is internal to the pump. I think of Headhunter Pumps when I say that.

Without an accumulator tank I don't know how the system modulates the pulses from the pump, or if the system is set up to handle the flow requirements of some toilets which need a constant pressure, high flow.

We had this discussion previously regarding HW heaters. Unless the HW heater is designed so it never loses an air cushion atop the contents of the HW tank (pressure HW tanks) the expansion of HW with no cushion will eventually cause the tank to expand and ultimately fail. Within every system except those with instant on HW tanks some means of handling expansion due to heating of the water must be considered.

But in Gary's case, he describes his pumps kicking on when no water is being drawn. Assuming he has no leak it is most probable his check valve(s) are leaking water back into the holding tank and that can be exacerbated by an accumulator tank with no pressure or the lack of an accumulator tank.

[gmcbuffalo]

Gary if you have been in any freezing weather you may have small crack in one of the water lines that is leaking into the coach. So look around for wet areas. Otherwise I agree with Jon that it may be the pumps internal check valve. I have had both issues on a hunting trailer I have. On my bus I have two pumps in parallel and had to adjust the pressure switches on them so they were equal. Until I did this one would run longer that the other after turning the water off and it would turn on sooner than the other. I found the one that was running longer by pulling the wires off each pump during this running issue with no water flow.
Greg

[Gary & Peggy Stevens]

Thanks guys, for all the answers and possibilities.

I am hoping JDUB's answer is the correct one. TOO FUNNY !!!! But worth the cost to help a charity, right JDUB ?

Gary S.

[jimblu]

The Shurflo 5.7 has the pressure switch and check valve in the pump. A check valve after it won't solve the problem if the pump is bad. It is a variable speed pump that doesn't pulse as much. I had two replaced on warranty and switched away from it. Maybe they are better now. If you can shut off the water after the pump and it still cycles the pump is bad. They don't tolerate dirt, they need a pre filter.