Hearing a pump running when connected to city water with pump turned off. Different pump

[JoeB-WO]

I am hearing a pump running, not the fresh water system pump, when I run water. I am connected to city water. The fresh water pump is turned off and not running. This sound appears to be coming from under the shower base. It runs for an indeterminate amount of time and starts when water is flowed.
This is a 2022 Dynamax Istata 3 24FW. All of the water system appears to operate normally. This is our first trip in this coach so we are still trying for wring out any issues. Any clue would be helpful. There will inevitably be disassembly involved when we get back home.
jcb

 

[Willhound]

Are you certain it's a pump? Could it be a water line vibrating with water pressure?

 

[Reverse_snowbird]

Check your outside 'wet bay'. I don't have your rig, but the same thing happened to us with our REV.
Took us forever, but we traced it to a second water pump switch in the wet bay.
The switch in the rig was off, but we'd accidentally turned on the water pump with the switch in the wet bay. It bypasses the switch in the rig and allows us to turn on the water pump from outside the rig.

 

[JoeB-WO]

Are you certain it's a pump? Could it be a water line vibrating with water pressure?

It is some type of an electric motor and it sound like a pump but it is not the normal pump that makes water pressure while dry camping. It is a different pump. Additionally it continues to run long after the water has stopped flowing. Pretty sure this is not a vibration.

 

[JoeB-WO]

Check your outside 'wet bay'. I don't have your rig, but the same thing happened to us with our REV.
Took us forever, but we traced it to a second water pump switch in the wet bay.
The switch in the rig was off, but we'd accidentally turned on the water pump with the switch in the wet bay. It bypasses the switch in the rig and allows us to turn on the water pump from outside the rig.

Nice thought. I don't have a switch in the wet bay, at least not one I have found yet. Again though, this is different from the normal water pump that runs while dry camping. It is a much quieter sound and coming from under the shower. The "normal" water pump is under the bed.
I have not found the port for winterizing the system, meaning adding anti-freeze to it either

 

[bikendan]

Moved thread from the Tech and Repair section to the Motorhome section's Dynamax sub-forum for better help from other Dynamax owners and possible factory support.

 

[Datsdad]

I've a '24 Isata 3 24FW, freedom series. The anti-freeze line is where the water tank is located. About a 1' corrugated tube.
As for the "pump sound". I've had the same issue at times. I believe I can hear a pump and even feel a vibration in the unit, but water pump is off. I'll be interested in what you find. I can't find a secondary switch...

Good Luck.

 

[Ddahle]

It could be coming from the Truma water heater. It has a circulation pump.

 

[bclemens]

^^This^^ Truma most likely. Open up the outside cover and see if you hear it there.

 

[JoeB-WO]

I've a '24 Isata 3 24FW, freedom series. The anti-freeze line is where the water tank is located. About a 1' corrugated tube.
As for the "pump sound". I've had the same issue at times. I believe I can hear a pump and even feel a vibration in the unit, but water pump is off. I'll be interested in what you find. I can't find a secondary switch...

Good Luck.

It turns out this is apparently "Operator Error". When the water source selector valve is set to "City Fixtures" and the water pump is turned on, the pump runs when you flow water. Interestingly, the noise is much quieter than when it solely is pumping water. When the flow of water is stopped, the pump continues to run for some period of time, like a minute or so. It seems like it is charging a volume like a pressure resivour or something similar. The noise from the pump is telegraphed to the floor of the shower. Someone suggested that I might be hearing a vibration of a pipe. I think this may be the mechanism that allows the sound to telegraph to the shower area.
In any event, once I discovered that the pump was still turned on, I was able to do some testing to prove that this was indeed the issue. The pump is turned off / on through a SW controlled panel and it is not obvious when the pump is energized so, while I believed the pump was off, it was actually on. My bad for sure!