Water pump running on city water

[deadeye916]

Wondering why my water pump runs when hooked to city water. If I turn the pump on it does not run, but when I turn on a water faucet in the coach the pump comes on. Is that normal? I recently replaced the factory 1.5g/m pump with the 5.7 Shurflo.

Is it because the city water pressure is lower than the setting on the pump? I believe the 5.7 is set for 65psi and I suspect the city water pressure is lower, so as soon as I turn on water the pump senses the drop in pressure and comes on.

[Bill Adams]

This is pretty common. If you turn off the water pump and turn on a faucet you will get a certain amount of water flow. Now, leave the faucet running and turn on the pump. You should see an increase water flow. You decide if you like the increase flow and if not then just turn off the pump. If you leave the pump on you will be using city water AND water from your holding tank. With the pump off you will have an unlimited supply of city water only.

[Gary RVRoamer]

Your pump turns on/off based on water pressure and is usually set to come on around 45-48 psi. If the city water pressure is high enough, the pump never comes on, but it it is less than about 45 psi, the pump will come on as well as the city supply.

[Wayne M]

Most of the in-line water pressure regulators provide 40 psi output. I guess that would mean that any pump designed to come on between 45-48 psi would constantly run when water is demanded. That really sounds strange. I'm not disputing it, but I'm surprised.

I don't believe a pump should run when there is no power supplied to it. I would be fearful if it did that it could come on by itself should a leak occur and no city water was hooked up. (I'd be fearful of any leak, city water or no city water.)

[wa8yxm]

There are 3 common ways to plumb a coach

I have a water pressure regulator (Sure-Flo) between the filter and the "house" this protects things that need protection, but it also limits the pressure to around 45PSI.. The pump can hit 50 so it will run.

If I hook direct to city water (80psi) the pump wont' run but... some things may "object" by leaking water all over the place.. Like the seals on the water valve in the toilet.... (The pipes will take way more pressure than that)

If I put a filter between the park and the rig.. pressure loss in the filter, even without a regulator, may be great enough for the pump to kick in.

NOTE: I use 2 regulators at some parks.. A "pre-regulator" (Watts) set to around 60-70 PSI protects hoses and filter from over 100PSI found in some parks

And the post-filter regulator (Sure-Flo)

WHY: Because of that pressure loss in the filter issue.

[deadeye916]

Thanks all who responded. My guess is the city water pressure is low enough, at least when I open a faucet, to allow the pump to sense the drop in pressure and come on to boost the pressure. I never tried turning on the original pump while on city water so I don't know if it behaved the same or not. As with everything else on the coach, I like to understand how these systems work so if/when something does go bad, I have some idea how to fix it. I don't think anythings broke now, but I wanted to be sure.

[Flagelpater]

FWIW My unit will turn the water pump Off after it runs consistently for about 10 minutes. I just can't remember the actual time right now. This is to prevent the pump from evacuating the entire Fresh Water supply due to a leak but more importantly to keep from overheating the pump if the tank is empty. The pump switch needs to be cycled Off and On to restore pump operation. This feature could confuse you while troubleshooting if you did not know it was there.

[EngineerMike]

Flagel- do you happen to know the name of that system? Sounds like a good upgrade. Mike

[Flagelpater]

Mike I will need to get the info in the morning. It was either FloJet or Surflo. I purchased it as an add-on in Quartzite a couple of years ago. It converts a constant speed pump to a variable speed. This prevents the shower water from going from Nice to Cold as the water pump cycles Off and On. It also virtually eliminates the loud banging noise as well. Camping World did sell it for a while but I have not seen it there for over a year.

[Flagelpater]

Mike I found the item. This is Not where I purchased it and way more than I paid for it! It was about $30.00 when I got it. Their new pumps should now have the same technology. FloJet Quiet Pump Controller - $75.99