Water Pump Kicks on while filling fresh water tank

[Peregordusmc]

I'll try to make this brief. Staying at a resort that shuts down water at the site during winter. They have a spot on the grounds you can fill your fresh tank. I had a 42 gal fresh tank laying around and a spare 12v pump. So, I put that in the back of the truck to fill up and use the spare pump to transfer it to the 5th wheel instead of hauling the trailer over to fill up. Normally when I do this the rv pump is turned off because we always leave it off unless we need to use the water. Today it was on when I switched the water valves from boondocking configuration to fill tank configuration and the pump kicked on. I did some playing around thinking maybe it was meant to pump from an external tank, but doesn't appear to be doing that. Maybe it was due to the second pump being inline also. So the question is, why would the pump be kicking on when you switch the valves to fill fresh tank?

2022 Heartland Fuel 364

Thanks in advance.

 

[Dahillbilly]

drop in pressure when you did the switch over, causing the pump to run. Just like opening a faucet drop in psi & pump runs. Turn pump off when changing valve position

 

[rhodies1]

Dahillbilly is correct. Pump will kick in because it loses pressure. Must be turned off .

 

[david-steph2018]

We are sitting in Key West on Sigsbee NAS boondocking. Last time we filled our water tank, it did the same thing. I forgot to turn the pump off first before switching valve position.

 

[LBR]

Always shut the pump off first and foremost. Then it is a great idea to bleed all pressure off by opening a faucet/holding toilet pedal down to relieve all pressure stress on the water selection valve.