Two-stage automatic changeover LP regulator for dual propane cylinder RV systems, with plastic cover and mounting bracket for protected installation.
The Flame King ACR-2 is a two-stage automatic changeover LP propane regulator for RVs, vans, trailers, and other approved dual-cylinder propane systems. It connects to two propane cylinders and automatically switches from the primary cylinder to the reserve cylinder when the primary runs empty.
The built-in indicator changes color when the selected cylinder is depleted, allowing the empty cylinder to be refilled while the system continues drawing from the reserve cylinder. This version includes the regulator with a plastic cover and mounting bracket, but propane pigtails and cylinders are not included unless separately stated.
Automatically switches from the primary propane cylinder to the reserve cylinder
High-capacity regulator for compatible RV LP gas systems
Color-changing indicator helps show when the selected cylinder is empty
Includes plastic cover and mounting bracket for protected regulator installation
Flame King lists the ACR-2 regulator inlets as 1/4" SAE inverted flare and notes compatibility with 12"–18" inverted flare pigtails such as E12INPT, E15INPT, or E18INPT. NPT pigtails are not recommended for the regulator inlets. Verify the RV propane system’s pigtails, outlet fitting, regulator orientation, bracket location, and LP line connection before installation. Propane work should be performed and leak-tested by a qualified person.
Before Starting: Turn off both propane cylinders and confirm the RV system uses a compatible dual-cylinder automatic changeover regulator. Verify inlet pigtail type, outlet fitting, mounting location, regulator orientation, and system pressure requirements before installation. Basic Use Steps: 1. Mount the Regulator: Install the bracket and regulator in an approved upright position with the vent properly oriented and protected by the cover. 2. Connect Cylinder Pigtails: Connect compatible 1/4" SAE inverted flare pigtails from each propane cylinder to the regulator inlets. Do not use thread sealant on flare fittings. 3. Connect Outlet Line: Connect the 3/8" NPT female outlet to the RV propane supply line using approved LP gas-rated fittings and sealant where appropriate for NPT threads. 4. Select Primary Cylinder: Turn the changeover lever toward the cylinder intended as the primary supply. 5. Open Cylinder Valves Slowly: Slowly open both propane cylinder valves to allow proper regulator operation. 6. Leak Test: Apply approved leak detection solution to all connections and repair any leaks before use. Never test for leaks with an open flame. 7. Monitor Indicator: When the selected tank becomes empty, the indicator changes color and the regulator switches to the reserve cylinder. 8. Refill Empty Cylinder: Close the valve on the empty cylinder, remove it for refill, then reinstall and leak-test before returning it to service. 9. Reset Primary Selection: After refilling, rotate the lever toward the active/full cylinder as needed to designate the next primary tank.
Package Contents: • 1 Flame King ACR-2 two-stage automatic changeover propane regulator • 1 plastic regulator cover • 1 long / L-style mounting bracket as supplied by manufacturer packaging NOT Included — May Also Need: • Propane cylinders • Propane pigtail hoses • 48" thermoplastic supply hose • RV propane manifold or hard line fittings • Thread sealant rated for LP gas where NPT threads require it • Mounting hardware not supplied by current packaging • Leak detection solution • Professional propane system installation or pressure testing This listing is for the regulator, cover, and bracket only unless otherwise stated. Confirm whether pigtails are included in the specific SKU or kit being ordered.
To confirm compatibility before ordering, have the following ready: • Current regulator model and photos of the installation • Number and size of propane cylinders • Existing pigtail fitting type and length • RV propane outlet line connection size • Available bracket and cover clearance • Total BTU demand of connected propane appliances, if known • Whether the system uses inverted flare pigtails or another fitting style • Any signs of regulator failure, such as low flow, red indicator, odor, freeze-up, or appliance flame issues Why this matters: Automatic changeover regulators must be matched to the correct inlet/outlet fittings, system pressure, mounting orientation, pigtail type, and appliance demand. A regulator mismatch can cause leaks, low propane flow, appliance malfunction, or unsafe operation.
Match this regulator by tank setup, inlet pigtail type, outlet fitting, regulator pressure, BTU demand, mounting orientation, and cover clearance. Do not select by “auto changeover” wording alone.
If propane system issues continue after regulator replacement, check cylinder fill, pigtails, valve operation, outlet pressure, appliance demand, leak status, and RV LP system condition.
Propane is flammable and can cause fire, explosion, injury, or death if installed or handled incorrectly. Turn off propane before service, use only approved LP gas fittings and sealants where appropriate, never use thread sealant on flare fittings, and leak-test all connections before use. If propane odor is detected, shut off the gas if safe, ventilate the area, avoid flames/sparks/electrical switches, and have the system inspected by a qualified propane or RV technician.