Works pretty much as advertised, but if used in campers/RVs is best used when outside power and water is available. Does work with onboard water pump but is very sensitive to water flow rate. If your 12 volt pump has marginal power the heater will not work at low flow rates and if operating and the cold water is turned on perhaps to have warm instead of hot, the heater will go off if the cold usage diverts too much flow from the heater. I use off the grid with a 12v solar powered pump and it works, barely. Directions provided are voluminous and confusing. User support is laughable. Had one tell me you need minimum of two inches between heater and wall behind it and in the same sentence say but thats ok if mounted on the wall. Also said minimum clearance from the ceiling was 12 feet. Also said the "required pressure relief valve" isn't really needed. English speaking but thats about it. The included vent is only 15 inches long and will only work if mounted on an outside wall and vented directly out the back. The vent pipe is an odd size and no adapter is provided although some factory answers to FAQ indicated it was. Mounting on the wall, marking position for vent cutout, and installing vent requires two people as it is awkward to say the least. The longer vent kits for any other mounting are fairly expensive and not included. I got a great buy from Walmart with great discount for store pickup, $170 total, and extra vent kit was more than that I think. For that price I am happy with the heater, poor installation instructions and tech support not withstanding.