Marshall Excelsior MEGR-253 automatic changeover regulators are offered as separate regulator assemblies and packaged configurations. When replacing an RV propane supply component, the part number on the regulator, the pigtail ends and the bracket all matter. This illustrated reference separates those pieces so you can identify what needs replacing before looking through UsedRVParts listings.
What belongs to the cylinder side and what belongs to the regulator?
In a standard two-cylinder setup, two separate cylinder hoses feed the regulator's two inlets. The auto-changeover body selects a propane supply and reduces pressure for the RV's downstream low-pressure gas system.
Service cylinder
Reserve cylinder
Compare standard and high-capacity MEGR-253 configurations
| Reference | What it represents | Replacement consideration |
|---|---|---|
| MEGR-253 | Standard two-stage changeover regulator body | Two 1/4-inch female inverted-flare inlets and one 3/8-inch female NPT outlet |
| MEGR-253P | Packaged standard-capacity regulator | Confirm the contents of the exact package; a P suffix alone is not a pigtail-length specification |
| MEGR-253P-PT15 | Catalogued regulator-and-pigtail configuration | 15-inch pigtail designation; confirm complete included components |
| MEGR-253P-PT18 | Different packaged regulator configuration | Do not substitute for PT15 from appearance alone; verify manufacturer kit contents |
| MEGR-253HP | High-capacity changeover regulator configuration | Match gas demand and correctly rated cylinder hoses rather than assuming it replaces standard capacity |
| MEGR900 / MEGRRVB | Mounting bracket options | Different physical bracket forms; compare mounting dimensions, holes and regulator support |
Marshall Excelsior lists the standard MEGR-253 at 225,000 BTU/hr primary and 150,000 BTU/hr reserve, with the MEGR-253H high-capacity model rated at 350,000 and 200,000 BTU/hr under its specified conditions. These figures are not universal ratings for every LP-gas regulator.
Choose pigtails and mounting hardware separately
The regulator's female inverted-flare inlets need matching male inverted-flare hose fittings, such as the proper MER425 family pigtails. The similar-looking MER426 family has male NPT pipe-thread hose ends and is not a direct substitution at these inlets.
Bracket part numbers should be checked against the existing installation: the MEGR900 and MEGRRVB have their own physical profiles, even when both are listed for members of the MEGR-253 family. Verify the mounting arrangement and regulator vent location with the factory instructions.
Find the model by product photograph
Compare these existing product listings with your installed model and fittings. Open each record for current condition, price and availability rather than assuming two similarly named kits contain the same parts.
More RV propane and appliance parts references
The changeover system connects upstream of the appliances. If a furnace or water heater is not operating correctly, its internal gas valve, controls and wiring must be identified from that appliance's specific model drawing.
Manufacturer model reference
Marshall Excelsior's MEGR-253 regulator data provides the inlet, outlet and capacity specifications. See also its MER425-15 hose description and the factory installation literature. The diagram above is an identification aid, not a substitute for manufacturer-approved gas installation and testing instructions.