It runs on propane only, so no 110V heating. You need to have a min of 1 Gal per min of flow to kick on the burner. Whats odd about this unit is, that if you turn on the cold water, you may not have enought water flow to fire up the burner. So they state only turnon the hot water.
Here is some info from their web site and installer guide.
Girard Tankless RV Water Heater Features:
It’s the Flow that Makes it Go!
The GSWH-1 Tankless Water Heater Operation is literally based on the flow of water. That is to say, that the temperature of the hot water coming out of the hot water faucet is determined by how open or closed the hot water faucet is; the faster the flow, the cooler the water; the slower the flow, the hotter the water. By adjusting the flow, RV’ers can literally have endless hot water! • Instant/Endless Hot Water* – An unlimited supply of hot water when you need it.• No Recovery Time – There is no tank to run out of hot water so you can shower all day if you want.• Energy Efficient – Uses 60% less LP Gas than Storage Tank Model Water Heaters.• Temperature Rise – 40° to 60° depending on water flow.• Induced Draft – Improves combustion, and efficiency. Not affected by high altitudes.• Dual BTU Burner - For improved efficiency, you can change the burner from Hi-Flame (34,000 BTUs) to Low Flame (27,000 BTUs) depending on the incoming water temperature.• Lightweight – Over 65% lighter (50 – 90 lbs. less) than conventional tank model water heaters.• State of the Art Electronic Ignition – No pilot lights or manual burners to keep lighting or adjusting.
Professional Installation is strongly recommended. (But where is the fun in that???)
The Girard Tankless Water Heater performs and operates differently than a "tank style" water heater so it is necessary to have sufficient Water Flow/Pressure, 12 Volt
Power and Gas Pressure. This is especially critical on older model RVs. To ensure proper performance and operation perform the following tests.
Check the RV’s plumbing system/fixtures to ensure that you have a minimum of one (1) Gallon per Minute (GPM) flow from each (Hot Water) Faucet(s)/Shower(s). Fully open the "Hot" Water Faucet for this test and then do the same test with the COLD Water Faucet(s). Check using the RV’s water pump and a "shore" water source. Late model RVs normal full flow rate is usually 1.20 to 1.50+ GPM.
Check all the RV’s Hot Water Faucets and confirm it can be adjusted from a steady low flow and gradually increase to a steady full flow (critical to achieve the desired consistent temperature).
Check for sufficient 12 Volt
Power (minimum of 11.5 volts to the Water Heater – 10 amp fused line).
Check Gas Pressure: required 11 – 12 WCI on the Water Heater Gas Line. Check LP pressure with ˝ of the RVs’ gas appliances (refrigerator, range/oven burners & furnace) operating/running.
If any of the above criteria is not met it may affect the performance of the Girard Water Heater in achieving and/or maintaining the desired Hot Water temperature (up to 60 degrees (F) temperature rise).