Little Giant Set Up Diagram
Little Giant Use Instructions

Operation Instructions for Hotomatic Gas Water Heaters 

**********Failure to follow these instructions could result in damage to your 

heater, a fire, and/or injury************* 
Install fire extinguisher at every service vehicle door opening.

1. Hook heater to LP gas supply tank with certified LP gas hose with regulator. The 

hookup is on the left side of the Unitrol gas valve. **Make sure the Unitrol gas 

valve is in the OFF position.** You should also make sure you are not smoking, 

and there are no open flames or sparks within 20 feet of the vehicle. 

2. Turn on the gas on the tank and check to ensure there are no gas leaks. You can 

use a spray bottle with soapy water mix to spray on the joints where your fittings 

are. If you see bubbles, you have a leak. 

3. Make sure the pressure relief valve is installed into the ¾” female “HOT” water 

outlet on the back side of the heater. ATTENTION: Use of this heater without 

a pressure relief valve voids your warranty and could cause damage to your 

heater and/or result in severe injury. 

4. Hook your wand into the “HOT” water outlet where the pressure relief valve is. 

5. Hook the cold water supply to the ¼” male nipple at the top of the heater. 

6. Turn on water, check for leaks, and double check to make sure coil is full. Failure 

to do so could cause a dry-fire situation on your coil, which will ruin your heater 

coil and could cause a rupture. A dry-fire is running your heater without water in 

the coil, which softens the metal and voids your warranty. 

7. Once the heater is full of water, you may turn the Unitrol gas valve to the 

“PILOT” position to ignite the pilot flame. You will then need to push the 

plunger down numerous times and hold it down on the last time to purge any air 

out of the lines. 

8. While holding the plunger down, you will then push the spark igniter down 

numerous times until you can see the pilot flame ignite. Keep holding the plunger 

down for 10-15 seconds so the pilot flame will heat up the thermocouple. You 

may then release the plunger, and the pilot flame should stay on. IMPORTANT: 

If the pilot flame does not light on the initial try, or goes out when you release the 

plunger, wait 5 minutes so that any built up gas will dissipate and reduce the risk 

of an explosion. After 5 minutes, start again at #7. 

9. Once the pilot flame is lit, you may then turn the on/off/pilot valve to the “ON” 

position and set the thermostat to the desired temperature range. AT THIS 

POINT, DOUBLE CHECK TO MAKE SURE YOUR WATER SUPPLY IS 

ON!!! The heater should then fire its main burner and heat until the desired 

temperature is reached. Once the temperature is reached, the main burner will 

shut off and the heater will go into a standby mode with the pilot flame still 

burning. If the pilot flame should ever go out, do not attempt to relight it for at 

least 5 minutes to allow dissipation of any built-up gas inside the heater. 

10. If you ever smell rotten eggs, this is a sure sign you are leaking propane gas or 

have a build-up of gas in the immediate area. STOP WHAT YOU ARE 

DOING AND TURN THE GAS VALVE OFF ON YOUR LP TANK. 

11. These heaters are designed to run 600psi max unless you have the high pressure 

coil which has the capacity of 1400-1500psi max. Running a psi higher than the recommended specs for your heater, even once, can result in a coil rupture and is 

NOT covered under warranty. We will know if you do, so don’t…  Please note the pressure relief valve is set for 1000 psi so once you set your pressure over 1000psi steam will spray out this relieve valve!  Be sure to install a hose from the relief valve discharge to your vacuum tank or under your service vehicle. 

12. These heaters have the capacity of heating the water to 180+ degrees F, please 

take any and all precautions to protect yourself, and your equipment, by following 

these instructions.