Under Pressure
The pump for the system is the SHURflo Smart Sensor 5.7. This is essentially the highest capacity pump for the RV market. We put this pump in the Version 1 vehicle and were eventually very satisfied with it. Eventually, because a flawed installation design reduced flow, but we didn't figure that out for quite a while.
The Version 1 installation was built in to a plastic toolbox with external quick release connectors so the unit could be removed from the vehicle, when not in use, during sub-freezing weather. As it turned out, the connectors, the same ones you might use on a garden hose, were restricting flow significantly. That problem was fixed by removing the internal "stops" from the connectors.
The new installation doesn't have that problem since the equipment compartment is heated. In the Version 1 installation we added an accumulator tank, at the suggestion of an RV technician, to help the flow. It was the small SHURflo device, with a 20 ounce capacity. The purpose of the accumulator is to act like a balloon, or capacitor, in the system and "store" some extra water under pressure. When the water is turned on, the pressure built up in the accumulator immediately provides a high, steady flow rate until the pump kicks in. Part of the "Smart" in the Smart Sensor pump is to provide this compensation without an accumulator tank. We decided to go ahead and use an accumulator in the new installation, and chose a two gallon stainless steel unit rather than the 20 ounce plastic unit.
Here is a picture of the pump/accumulator installed.
Below are some graphics of the units, and below them links to more information on the pump, including troubleshooting and parts.
