The Hydro-Hot system serves two primary functions within the RV - to provide a supply of on-demand hot water, and to provide interior heating. Diesel fuel, drawn from the main fuel tank, 120-Volt AC, or a combination of both, are required to operate the Hydro-Hot system. A switch panel designating the preference of using diesel fuel or 120-Volts AC is installed for convenience, and allows users the option of using one or both energy sources at the same time.

Diesel fuel is the most efficient energy source to bring the Hydro-Hot system up to operating temperature in the least amount of time. When the system is engaged, the green indicator light on the diesel control switch will illuminate and an audible roar will sound from the diesel burner. At this time the outside exhaust of the Hydro-Hot will be warm to the touch. Do not place your hand in front of the exhaust and risk injury from burns.

During mild weather temperatures, and when you expect a low demand for on-board hot water, operating the Hydro-Hot is easily accomplished using 120-Volts AC through a supply of shore power, or the on-board generator. When hooked to shore power, consider choosing to run energy sources simultaneously to insure a quick and efficient supply of on-demand hot water.

The inverter is not wired to supply battery power voltage to the Hydro-Hot system to prevent the risk of discharging the house or chassis batteries through excess discharge from the Hydro-Hot system. However, 12-Volt DC power, which is provided from the RV house batteries, is required to operate the Hydro-Hot switch panel located inside of the RV, the electronic controller located in a passenger side storage compartment, and comfort control thermostats installed inside of the motor home.

Therefore, the house and chassis battery banks must be charged, and all battery cutoff switches must be turned to the ON position, to operate the Hydro-Hot system. When the main house battery disconnect is switched to ON, current is passed to the house power solenoid. This signal will require the interior battery cut off switch to be turned ON to enable power to the house 12-Volt DC fuse panel.

The interior battery cut off switch is located directly inside the RV entry door. This switch will need to be ON to provide power to the comfort control wall thermostat. When the battery cut off switch at the entry door is ON, current will then pass along a set of 14-guage wires to the 12-Volt DC continuous duty solenoid. The solenoid will then engage, allowing current to pass to the house 12-Volt DC fuse panel. The house 12-Volt DC fuse panel, in most cases, is a fuse that is dedicated for the AC modules or thermostat. This fuse may be labeled 'Hydro-Hot,' or 'AC MOD.'

Once the main battery disconnect switch and the battery cut off switch is set to ON, the sub-systems of the Hydro-Hot system are then powered for use.

The Hydro-Hot system does not simultaneously supply both interior heat and hot water, but instead relies on a domestic water priority system to interrupt interior heating upon a demand for hot water. Interior heating will again commence once the demand for hot water ceases. During cold weather temperatures, you may find it convenient to postpone interior demands for hot water until the Hydro-Hot has had ample time to heat the interior of the RV. Once interior heating is interrupted in order to obtain hot water during cold exterior temeperature conditions, avoid opening and closing the RV entry door to retain existing interior heat until such time as the Hydro-Hot system is once again providing interior heat.

Located in the passenger compartment, next to the Hydro-Hot tank system, is an electronic controller. In the event the Hydro-Hot system fails to operate once all operating conditions have been met, the electronic controller can become a valuable tool in quickly troubleshooting potential problems with the system by pinpointing a particular fault within the system at a glance.

Lights aligning the panel of the electronic controller are well marked for easy reference. Green illumination of any light within the panel is indication of favorable working conditions. Any red light indicates a fault condition. Becoming familiar with the various operating designations within the electronic controller, as well as working knowledge of light indications, will help you to efficiently diagnose problems with the Hydro-Hot system.

The Emergency Cutoff lamp will indicate when there is a low liquid level in the heat tank, a strong impact to the unit, or when power has been disconnected from the system for an extended period of time. Low voltage supply may also trip the Emergency Cutoff Switch, causing the Hydro-Hot system to cease operation because the RV house batteries have reached a state of charge insufficient to operate various sub-systems that comprise the Hydro-Hot system.

In the event a red light illuminates in the Emergency Cutoff lamp, the electronic controller must be manually reset. Using a small screwdriver, or one end of a paperclip, reset the Low Voltage/Reset button located on the electronic controller.

Heating the interior of the motor home requires that the comfort control be turned on, and set to furnace. When there is a call for heat, the system will activate the circulation pumps only after confirming there is no demand for domestic hot water. While interior heat is supplied through the Hydro-Hot system, the fan speed selector switches (certain models) will have power applied and produce an audible sound when engaged.

The expansion tank, a clear plastic bottle, resembling a small version of the engine coolant reservoir, is generally located on the bay wall next to the Hydro-Hot system, or in the fuel tank bay. When the Hydro-Hot system is at operating temperature, visually inspect the coolant level of the tank on a monthly basis, and refill as needed. Refer to the manufacturer's manual for specific instructions on system operations, winterization procedures and maintenance requirements.

Once per year, have the Hydro-Hot system tuned up by a qualified technician to assure ongoing performance of the system when needed. When storing the RV during freezing temperatures, winterize by draining the Hydro-Hot system of water. The Hydro-Hot system is still available for use in interior heating during storage following winterization.