The Oasis SCH33 is an advanced and efficient hydronic heating system designed for recreational vehicles, offering space heating, domestic hot water, and optional engine heat management. It operates on 12VDC power and uses a diesel-fired burner as its primary heat source, supplemented by an electric heating element when AC power is available.
Function Description:
The core function of the Oasis SCH33 is to provide hydronic heating. It circulates a heat-transfer fluid (propylene glycol-based coolant) to remote-mounted, fan-equipped, radiator-style heat exchangers for space heating. The same heated fluid can be circulated through an optional, highly efficient, externally mounted flat-plate heat exchanger to provide a continuous supply of domestic hot water through a mixing valve. The system also offers optional engine waste heat utilization for supplemental heating and an optional engine pre-heating feature using a secondary water pump. The system is electronically controlled with automatic safety shutdowns, manual reset overheat temperature sensors, and thermal cutoffs. It supports up to four separate space heating zones, each with its own optional thermostat.
Important Technical Specifications:
- Heat Sources: 33,000 BTU (true output) diesel burner (12VDC), 1500 Watt, 120 VAC (North America) electric immersion element (or 1500 Watt, 240 VAC Europe). The electric element provides an additional 5,000 BTUs of heat.
- Fuel Type: Diesel #1 and #2 only.
- Fuel Pump: Maximum flow capacity of 32 GAL/Hr, maximum pressure of 11.5 psi. A 10-micron fuel filter is recommended.
- Heat Transfer Fluid: Non-toxic, propylene glycol-based coolant with FDA-recognized "GRAS" additives. A 50/50 mixture of distilled water and propylene glycol (nontoxic antifreeze) is recommended.
- Domestic Hot Water: Increases ground water temperature by 60°F at a flow of 1 GPM (using only the diesel burner). External mixing valve factory set to 120°F (49°C), adjustable from 75°F (24°C) to 145°F (63°C).
- Dimensions: 7.5"H x 11"W x 18.8"D (19.1 cm x 27.9 cm x 47.8 cm).
- Weight (full): 57 lbs. x 2 = 114 lbs./51.7 KG (mounting location must support double this weight).
- Exhaust System: Steel (or stainless steel) 1½" ID exhaust piping, maximum length 12′ (without bends). Each 90° bend reduces allowable length by 2 feet. Minimum 3” (7.6 cm) clearance from all surfaces.
- Combustion Air Intake: 2" combustion fan intake hose.
- Electrical Power: 12VDC (primary), 120/240 VAC (for electric element). Primary DC power requires a dedicated 25-amp fuse or breaker.
- Internal Circulation Pump: For heating loop and hot water heat exchanger.
- Heat Transfer Fluid Tank: Unique, self-purging, 1.2 US gallon, welded and insulated stainless steel tank.
- Fan Heaters: ITR offers various 12VDC fans: Small Space (0.5 Amp, 4000 BTU/h), Low-Profile (1 Amp, 6000 BTU/h), Standard (0.9 Amp, 8700 BTU/h), High Output (1.6 Amps, 12000 BTU/h), Defrost (10 Amps, 20,000 BTU/h with 3-speed switch). Total fan amperage draw is limited by the Zone Control Board (10 Amp limit for all fans across four zones, 5 Amps per zone).
Usage Features:
- Quiet Operation: Insulated enclosure and design minimize noise.
- Low Power Consumption: Efficient design for extended use.
- Direct Ventilation: Sealed combustion chamber uses outside air, preventing exhaust smell or smoke inside.
- Simple Ignition: Low amperage draw ignition.
- Return Fuel Line: Eliminates air and prevents nuisance shutdowns.
- Control Panels: Basic or Touchscreen remote control panels with Wi-Fi (option 2) for operational control, fault reset, and diagnostics.
- Multi-Zone Heating: Up to four thermostats for separate temperature regulation.
- Domestic Hot Water On-Demand: Continuous hot water without storage tanks (with optional external heat exchanger and mixing valve).
- Engine Waste Heat Utilization: Uses engine waste heat for supplemental heating (with optional external heat exchanger).
- Engine Pre-Heat: Optional feature to pre-heat the engine before starting for easier ignition and immediate load (requires additional pump and switch).
- Easy Access: Hookups and connections are easily accessible from the top of the heater for installation and servicing.
- Fault Diagnostics: LED diagnostic code indicator on the control board and remote panel to pinpoint faults.
- Bypass Mode: Service feature for authorized personnel to override safety devices for troubleshooting (runs for five minutes).
Maintenance Features:
- Initial Inspection: General inspection of the entire system recommended two weeks after initial operation, checking for leaks and tightening clamps.
- Regular Operation: Strongly recommended to start and run the heater through one complete heating cycle at least every 30 to 45 days to ensure proper function.
- Coolant Level Check: Monthly check of coolant level in the overflow bottle (3/4 full when hot). Fill only when the system is COLD and in small quantities to prevent overfilling.
- Exhaust/Air-Intake Check: Monthly inspection for obstructions.
- Fuel Lines/Filter Check: Monthly inspection for leaks and integrity. External fuel filter should be checked seasonally for clogging/replacement.
- Annual Service Tune-up: Recommended by a trained service technician prior to the operating season.
- Component Replacement: Igniter, fuel filters (nozzle filter and external filter), and air compressor filter should be replaced annually (as opposed to just inspected/cleaned).
- Major Component Examination: Air compressor, fuel pump, fuel nozzle, and combustion air fan should be examined for wear and serviced/replaced by a technician as required.
- Combustion Tube Inspection: Annually inspect for wear and soot/ash deposits. Clean with vacuum or remove and clean if deposits are significant.
- Hose/Tube Check: Annually check water, air, and fuel hoses for leaks, weak points, and deterioration. Replace worn sections.
- Electrical System Check: Periodically ensure secure connections, voltage test for 12 volts from the battery, and check for corrosion.
- Nozzle Cleaning: The nozzle can be disassembled and cleaned during routine maintenance to prevent clogging and maintain flame quality.
- Winterization: Protect the system from cold temperatures and corrosion using a proper mixture of anti-freeze and water. Potable water lines should be flushed with winterizing antifreeze or blown out with air.
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