Introduction
This section serves as a guide for installing a generator set in recreational vehicles. For specific service instructions, refer to the Operation Manual. Installation must comply with current standards: (1) ANSI/RVIA EGS-1, (2) ANSI A 119.2/NFPA 501 C, and (3) applicable articles of ANSI/NFPA 70, National Electrical Code. State and local requirements must also be met.
⚠ WARNING: Marine Application!
RV generator sets do not comply with United States Coast Guard (USCG) requirements and must not be used for marine applications. Only generator sets specified for marine use in marine installations are permitted. USCG regulation 33CFR183 requires a generator set to be "ignition protected" when used in a gasoline-fueled environment.
General Information
This section covers Kohler RV generator set models listed below. To determine the model, check the nameplate attached to the generator frame. Follow all instructions for proper installation.
| Model No. | Engine No. | Volts | Hz | kW | Phase |
|---|---|---|---|---|---|
| 12.5CC067 | Yanmar 4TN82-U (early models) Yanmar 4TN82-R (later models) | 120/240 | 60 | 12.5 | 1 |
Features
Generator sets feature Yanmar 4TN82-U or 4TN82-R diesel engines, a rotating field alternating current generator, and relay controllers. Each generator is directly connected to the engine for permanent alignment. Each controller includes a START/STOP switch for test operation. Early model controllers (without accessory plug P2) require remote operating controls to be connected to the terminal strip inside the controller. Later model controllers include an accessory plug (P2) for connecting the remote switch, preheat switch, and generator "ON" lamp wiring harness.
All Kohler RV sets are mounted on a steel mounting tray for quick installation. After attachment to the frame and coach-supplied radiator/hose connections, operational setup typically involves connecting fuel line, remote switch, load leads, battery terminals, exhaust system, and adding coolant/oil. Consult the Specification Chart for installation aid.
ℹ NOTE
When selecting and installing a radiator, consult Kohler Co., Generator Division, Product Applications Dept., Kohler, WI, 53044, Telephone (414) 565-3381 for recommendations and instructions.
Installation Factors
Each generator set is received as a unit, except for optional exhaust system components shipped loose for assembly. When preplanning installation, the following factors must be considered:
- ELECTRICAL LOAD: Does the selected set have adequate capacity to handle the load?
- COMPARTMENT SIZE: Will there be sufficient room around the set to maintain minimum clearances?
- AIR REQUIREMENTS: Are the compartment air inlets and outlets sized to allow adequate circulation of air for cooling and combustion?
- COMPARTMENT FLOOR: Is the compartment floor strong enough to support the weight of the generator set?
- COOLING SYSTEM: Is the cooling system large enough to cool the generator?
- FUEL SYSTEM: Is the system properly designed to prevent fuel starvation of either the main engine or generator set engine?
- EXHAUST SYSTEM: Will the system meet all safety requirements after installation?
- ELECTRICAL CONNECTIONS: Will all systems (battery, load, and remote switch) when connected, be compatible with vehicle system?
Each of these considerations is covered in detail on the following pages.
Electrical Load
While the electrical load of the vehicle should have been calculated prior to purchase, recheck the load before installing to ensure ample capacity and prevent overloading.
Lighting Load
Lighting load is usually easiest to calculate by adding the wattage of each lamp operated off the generator set AC circuit. Ensure total includes only lights on the generator set AC circuit, not DC powered lights. Accurate calculation prevents overloading, especially if other motor loads start up simultaneously.
Motor Loads
When figuring generator set capacity for motor loads, consider the high "in-rush" or starting current (2 to 5 times higher than normal operating speed). Reserve capacity must account for in-rush demands plus other simultaneous loads.
Air conditioning units are common motor loads in RVs. Starting characteristics vary greatly; some 12,000 Btu units may have lower starting requirements than 10,000 Btu units of another make. For a single unit, starting is usually not a problem if lighting/appliance load is not too high.
The trend is towards larger capacity air conditioners and multiple units. Simultaneous starting of two units can cause problems if capacity is marginal. Due to variations in starting characteristics, this publication does not make definite statements on multiple-motor starting capabilities. Consider delayed starting or "easy starting" devices if multiple motors are involved. Table 2-1 and 2-2 provide guidance for selecting generator set capacity. Capabilities vary according to "Kilowatt Derating." For specific information on simultaneous starting, contact Kohler Co., Generator Division, Product Applications Dept., Kohler, WI 53044, Telephone (414) 565-3381.
| Motor Requirements | 1/4 hp | 1/3 hp | 1/2 hp | 3/4 hp | 1 hp | 2 hp | 3 hp |
|---|---|---|---|---|---|---|---|
| Starting (In-Rush) | 750 | 1000 | 1500 | 2000 | 3300 | 4000 | 5000 |
| Running Watts | 350 | 400 | 600 | 750 | 1100 | 2000 | 3000 |
| Model | Radiator Type | Wattage | Will Operate Air Conditioner of Size Indicated | "Power to Spare" for Lighting Appliances, Tools |
|---|---|---|---|---|
| 12.5CC067 | Remote | 12,500 | Three 13,500 Btu | 6000 Watts |
Appliance Loads
Generator sets in recreational vehicles often furnish AC for appliances like TV, stereo, electric water heaters. Except for resistance-type loads (e.g., water heater), appliance requirements are usually low. However, these loads must not be overlooked when calculating total requirements. Reserve capacity should be available to avoid overloading. Average power requirements of common electrical appliances are listed in Table 2-3.
| Electrical Appliance | Rating (Watts) |
|---|---|
| Blanket | 50-250 |
| Blender | 600 |
| Dryer, Hair | 500-1200 |
| Fan, Air Circulating | 25-100 |
| Fan, Furnace | 270 |
| Heater, Space | 750-1500 |
| Heater, Water | 1500 |
| Pan, Frying | 1200 |
| Percolator, Coffee | 650 |
| Radio | 50-100 |
| Television | 300-750 |
| Toaster | 750-1200 |
Kilowatt Derating
All units are rated at 1.0 power factor. The kilowatts of the generator set will decrease 3.5% per 1,000 ft. (305 m) above 500 ft. (152 m) above sea level. Derate 1% for every 10° F (5.5° C) above 85° F (30° C).
Compartment Size
When planning compartment size, allow minimum clearances for cooling as shown in Table 2-4. The generator set must be securely fastened to avoid movement from vibration and road shock. A typical installation uses a mounting tray supported by angle iron with a full door for service access. The tray must be secured with the same number of bolts as mounting holes.
When designing the compartment, allow sufficient room for easy removal during major service. The compartment door must have air intake openings with a free area equal to or greater than specified under "Air Requirements." Ensure the compartment is vapor tight and sealed off from the vehicle interior to prevent exhaust or other items from entering.
Line the compartment with fireproof or highly resistant sound deadening material. A 3-layer foam material is efficient for sound absorption and can be installed with fire retardant adhesive. Fiberglass insulation with a heat barrier has also been used successfully.
ℹ NOTE
Since the sets are flexibly mounted, minimum clearances ensure the compartment sides and the set do not rub during operation or transit.
| Location | Clearance |
|---|---|
| Front | 1-1/2" (38 mm) |
| Side | 1-1/2" (38 mm) |
| Top | 1-1/2" (38 mm) |
| Rear | 1-1/2" (38 mm) |
The thickness of insulating and sound deadening material must be considered when planning clearances. Enlarge the compartment if necessary to maintain minimum clearance requirements.
Figure 2-1. Slide Tray Feature for Complete Removal: This diagram illustrates a generator set mounted on a slide tray, allowing it to be pulled out for complete service access. It shows the generator unit within a compartment, with the tray extending outwards.
Air Requirements
Each engine has a high water temperature shutdown switch that automatically shuts down the set if operating temperatures climb too high. To prevent shutdown, ensure compartment openings are large enough for adequate cooling air circulation. Minimum free air opening in the compartment door is shown in Table 2-5. Louvers, screens, and decorative grill work restrict effective air flow; even a simple mesh screen can restrict air flow by as much as 45%. Increase intake opening to compensate for such restrictions.
| Model | Inlet | Outlet |
|---|---|---|
| 12.5CC067-RV (Remote Radiator) | 350 Sq. In. (2258 Sq. Cm.) | 700 Sq. In. (4516 Sq. Cm.) |
Figure 2-2. Inlet Screen and Louvers Restrict Air Flow: This diagram shows an example of a wide mesh screen and louvers installed in an air intake opening, illustrating how they can restrict airflow into the generator compartment.
Cooling System
Use the following data for designing and installing the generator set cooling system to ensure a safe, effective installation. Kohler Generator offers three radiator assemblies that meet these requirements. Select the appropriate radiator assembly for the generator installation.
General guidelines are provided due to the multitude of coach manufacturers and generator installations. In a typical installation, the radiator assembly is in the same compartment as the generator. If a blower fan radiator assembly is used, cooling air is drawn across the generator and engine and then through the radiator. If a suction fan radiator assembly is used, the suction fan pulls cooling air through the radiator and then past the generator set. If the radiator assembly alone is used, the installer must supply an electric blower or suction fan to circulate the cooling air. Depending on space limitations, the radiator can be located in front of, adjacent to, or in a ventilated location remote from the engine (maximum 10 ft. distance). To prevent recirculation of heated air, maintain a tight seal between the radiator and the discharge chute. The discharge chute opening should be approximately one and one-half times the radiator core size.
ℹ NOTE
If the radiator is in a separate compartment from the engine, consider engine combustion air and heat rejection requirements. A supplemental cooling fan (1000 cfm / 28.32 m³/min) should be installed to supply air to the generator compartment.
Connect radiator fan motor to generator output leads L1 and L2. If a non-Kohler radiator assembly is installed, ensure the radiator fan motor rotates in the correct direction and is of proper voltage. To protect against overload and short circuits, fuses (adequate for the motor) are recommended between the fan motor and the L1/L2 connections.
⚠ CAUTION
The cooling system fill (radiator or expansion tank) must be the highest point in the cooling system. If not located as directed, cooling water will not completely fill the engine, leading to overheating and disablement of the high water temperature shutdown switch.
A close relationship exists between cooling system design and generator compartment size. Space availability often determines cooling system design. Refer to "Compartment Size" section before designing and installing the cooling system.
Figure 2-3a. Typical Cooling System Installations: This diagram illustrates two common cooling system setups. The top shows a "Generator Cooled by Blower Fan" where air flows from the air intake, through the generator, and is discharged by a blower fan. The bottom shows a "Generator Cooled by Suction Fan" where air is drawn by a suction fan through the radiator and past the generator, then discharged. Both emphasize maintaining a tight seal around the radiator.
Figure 2-3b. Radiator Fan Electrical Connections: This diagram shows a simplified electrical schematic for connecting a 240V fan motor to the generator's L1 and L2 outputs, with fuses and circuit breakers for protection. It includes connections to WDG. NO.1, WDG. NO.2, AUX. WDG., AVR, and FIELD WDG. (ROTOR).
Figure 2-3c. Cooling System Fill: This diagram illustrates the cooling system fill points, showing the radiator inlet and outlet, an overflow tank, and explicitly noting that the cooling system fill must be the highest point in the cooling system.
Cooling System Components
- Radiator with Motor-Driven Blower Fan (Does not include radiator fill cap; installer to provide fill/expansion tank. Includes mounting brackets): Kohler Part No. PAA-258570
- Radiator with Motor-Driven Suction Fan (Includes mounting brackets): Kohler Part No. PAB-258598
- Radiator Assembly (alone): Kohler Part No. A-258591
- Radiator Hose Adapter *, 1.25 in. hose (I.D.) to 1.5 in. hose (I.D.): Kohler Part No. 259491
- Radiator Hose Adapter *, 1.25 in. hose (I.D.) to 1.75 in. hose (I.D.): Kohler Part No. 259492
* One required for installation of listed radiator assemblies
Radiator Specifications (radiators designed to meet these criteria)
| Parameter | Value |
|---|---|
| Water Flow | 12 gpm (46 Lpm) |
| Heat Rejection | 1150 Btu/min. |
| Air Flow | 3000 cfm (85 m³/min.) |
| Radiator Pressure Drop | .04 psi (.275 kPa) |
| Air to Boil (ATB) | 125°F (51.6°C) |
| Radiator Cap Pressure | 7 psi (48.2 kPa) |
| Coolant Capacity | 4 gal. (15.1 L)** |
| Dimensions | See Installation Drawings |
** Radiator capacity only. Cooling system capacity also affected by radiator hose length.
Cooling System Specifications (Design cooling system and compartment so generator set meets these specifications)
| Parameter | Temperature |
|---|---|
| Engine Inlet Water Temperature (maximum) | 186°F (85.5°C) |
| Engine Outlet Water Temperature (maximum) | 196°F (91.1°C) |
| Engine Oil Temperature (maximum) | 250°F (121.1°C) |
| Combustion Air Temperature | 120°F (48.8°C) or 15°F (-9.4°C) Over Ambient |
ℹ NOTE
Ambient temperature is defined as the temperature of the generator operating environment. In RV applications, ambient temperature is the temperature inside the generator compartment.
Other Pertinent Information
| Parameter | Value |
|---|---|
| Thermostat Rating (Yanmar Engine) Start to Open | 157°F (69.5°C) |
| High Water Temperature Switch Rating (Yanmar Engine) | 230°F (110°C) |
| Maximum Distance Radiator to Generator Set | 10 ft. (9 m) |
| Generator Set Dimensions | See Installation Drawings |
Fuel System
The diesel fuel system for the generator set must be designed to operate independently of the vehicle engine system if both engines are to operate simultaneously. The best method is separate fuel tanks, but this is often impractical due to space restrictions. Most installations use a common tank with a separate dip tube arrangement, as shown in Figure 2-3c, to prevent the smaller generator engine from being starved by the larger vehicle engine. The generator set dip tube is generally shorter than the vehicle dip tube, which may lead to fuel unavailability when the supply is low.
A simple tee fitting is sometimes used for both engines from a common tank, but this usually prohibits simultaneous operation and can lead to draining the fuel line of the other engine, making starting difficult. The tee arrangement should be avoided or used only as a last resort.
When routing the fuel line from the main tank to the generator set, keep lines as short as possible and maintain adequate clearance from the exhaust system. Fuel lines must run along the frame or under the carriage, never inside the coach. Locate fuel lines below the generator set compartment with entry near the fuel pump. The fuel line must be of adequate size to handle fuel flow and withstand road shock and year-round climate. If steel tubing is used, it should be 1/8" (3.2 mm) I.P. (minimum) with an 8" (203 mm) (minimum) flexible section to allow free movement of the generator set.
⚠ WARNING: Dangerous Fuels!
Use extreme caution when handling, storing, and using fuels—all fuels are highly explosive in a vapor state. Store fuel in a well-ventilated area away from spark-producing equipment and out of reach of children. Never add fuel to the tank while the engine is running to prevent spilled fuel from igniting on contact with hot parts or from ignition spark. Keep fuel lines and connections tight and in good condition—do not replace flexible fuel lines with rigid lines. Flexible sections prevent breakage due to vibration. If any fuel leakage, accumulation, or electrical sparks are noted, DO NOT OPERATE GENERATOR SET. Systems must be repaired by qualified specialists before resuming operation.
Figure 2-3c. Two Dip Tubes in Fuel Tank: This diagram illustrates a fuel tank with two separate dip tubes. One dip tube extends deeper into the tank for the vehicle engine, while a shorter dip tube is shown for the generator set, ensuring the generator's fuel line is kept away from the exhaust.
⚠ WARNING: Fire Hazard!
Keep the compartment and generator set clean and free of debris and combustible materials to minimize chances of fire. An opening is provided in the mounting tray as a safety feature to allow any fuel or oil leakage to drain out. Ensure this opening is not blocked when the set is installed. If sub-flooring is used, cut a corresponding hole for this drain opening.
Exhaust Systems
Because the length varies with most installations, a tail pipe is not furnished with the kits. A tail pipe must be installed to direct exhaust gases beyond the vehicle perimeter. Use a tail pipe with as few gradual bends as possible to avoid excessive back pressure and face tail pipe away from normal air stream.
⚠ WARNING: Lethal Exhaust Gas!
Do not use flexible tail piping as this type could crack or break and allow lethal exhaust fumes to enter the vehicle.
Electrical Connections
Battery, load lead, and remote switch panel connections are needed to complete the installation. Make final connections to the battery only after all other connections have been made to prevent unintentional starting.
Specific details on each connection are stated in the following paragraphs. Refer to the wiring diagram for specific details—connections should be made only by qualified electricians. All wiring to the generator set must be securely supported or harnessed to prevent abrasion. Additional support is required to prevent exposure to the exhaust system and drippage of fuel, oil, or grease—at least 2" (51 mm) clearance must be provided between electrical wiring and hot exhaust parts. Wiring must not be located directly below or in close proximity to fuel system parts or oil fill locations. Other points to consider when making AC load connections are covered in the following.
ℹ NOTE
Wiring connections made at the time of installation should be accessible for inspection and servicing.
⚠ WARNING: Lethal Exhaust Gas!
When installing exhaust system, position tail pipe end so that discharged exhaust gases are not drawn into vehicle interior through windows, doors, air conditioners, etc.
⚠ CAUTION
Ensure exhaust system components are positioned well away from the drain opening in the bottom of the mounting tray. Also ensure components are not blocking access to the oil drain plug.
Figure 2-4. Floor Template: This diagram provides dimensions for a floor template for the generator set. It shows overall dimensions of 45-3/16" (1148 mm) in length and 26-9/16" (675 mm) in width. Key features include 10 mounting holes (21/32" / 17 mm diameter) and an oil drain opening (2.00" / 51 mm diameter) located 12-25/32" (324 mm) from the generator end. Various other measurements for hole placement are also indicated.
Wiring Diagrams Summary
The initial pages of this document (pages 1-16 and 1-18) contain detailed wiring diagrams for the 12.5 kW Tray Mounted Model Generator Mounted Controller and the Remote Mounted Controller (with accessory plug P2). These schematics illustrate the electrical connections for components such as the starter, fuel pump, AVR, glo-plugs, various relays (PREHEAT, REMOTE START, STOP), switches (PRIME, STOP, PREHEAT, START, REMOTE SW.), and the generator itself, including voltage regulator and end bracket connections. They also show connections for engine components like the air heater, high engine temperature switch, low oil pressure switch, and sending units for oil pressure and water temperature. For precise wiring details and troubleshooting, refer to the original PDF document.
