The following instructions are for a Surburban DSI water heater with gas/electric option.
Gas Operation
1st. Make sure the heater tank is full.
2nd. Open the propane tanks slowly.
3rd. Turn on switch inside trailer marked Water Heater. A red light will come on. The light will stay on until the water heater lights. The water heater will make three attempts to light then it will need to be recycled. Lighting the stove first will help purge the gas line of any air which will help the water heater light faster.
4th. Wait about 20-30 minutes and enjoy hot water!
Electric
1st. Make sure the heater tank is full.
2nd. Check to make sure the breaker inside trailer marked water heater is on.
3rd. Outside the trailer, behind the access panel there is a small black rocker on/off switch. Usually located behind some tubing in the lower left. There may be a pin in the switch locking it closed. Remove the pin and turn switch to the on position.
4th. Wait about 30 minutes and enjoy hot water!
You may use the gas or electric seperately or both at the same time, which will help with a faster recover time when taking showers, etc...
Hope this helps.