Gas grills, like any other appliance, are designed and engineered to definite
specifications with specific components. There is no single and easy way to safely
or properly convert your grill by simply drilling the orifice or changing the supply line.
All components have to be considered to maintain the integrity and safety of the
Certification and Design.
Gas Grills are designed and certified to operate on a single type of gas supply. The
type of gas will be shown on the nameplate data. Although some premium brand
manufacturers offer conversion kits, in the majority of cases if you change the supply
type or convert your grill from one type to another you will void all warranties and
certifications. Check with your local dealer or the manufacturer.
Propane or L/P Gas Supply.
Grills operating on propane operate at a higher gas pressure than those on natural
gas. The operating pressure is determined by the regulator. On those homes
using propane as a gas source, a grill set up for propane can generally be supplied
directly from a house line as the pressure is regulated at the tank. Check with your
propane dealer to assure compatibility.
Natural Gas or N/G Gas Supply.
Although the natural gas pressure supplied to your home is regulated by your local gas
company, some grills designed for natural gas also incorporate an additional regulator at
the grill to assure the maximum gas pressure supplied to the grill. The majority of
newer natural gas models do not use an additional regulator and connect directly to the
home natural gas supply line.
Grill models are individually designed to operate at specific BTU ratings. The BTU
rating is a measurement of how much heat your grill will generate and this rating can be
found on the nameplate data on your grill.
The nameplate data may state the Btu rating in two
different ways - as per burner or as a total rating for the grill. As an example the
rating may be 40,000 Btu's total or 20,000 Btu's per burner. (This becomes
particularly confusing when you model incorporates a "dual" burner which is
manufactured as a single unit with each side individually controlled by it's own control
knob. In this case each side would have a 20,000 Btu rating for a total of 40,000
Btu's.) With several exceptions, most grills do not exceed a total 40,000 Btu
The valve orifice fitting is the fitting at the end of the valve which has a small hole
drilled into it's center. Most orifice fittings will have their size stamped either
on the top or side of the fitting. The orifice size is the actual hole
diameter in the orifice fitting. Drill bits although most commonly sold by inch
increment size are also available by number. Thus a #56 size orifice is an orifice
fitting that has been drilled with a #56 drill bit. Drill bit numbers and sizes have
an inverse relationship. The larger the number, the smaller the drill bit.
(Orifice hole size will be larger for natural gas supply models than propane because of
the lower natural gas operating pressure).
The actual Btu output is determined by the pressure of the gas supplied, volume of gas
which is regulated by the valve and by the orifice fitting orifice hole size. As an
example, assuming a fixed natural gas pressure of 3.5 inches of water column a #48 orifice
will give a different Btu output than a #46. (Altitude also affects the Btu rating.)
Orifice Size Guide
Control valves regulate the volume of gas supplied to the burner.
Valves have specific maximum Btu ratings and are ported internally to specific
sizes. This means that if you are attempting to convert from propane to
natural gas, the volume of gas supplied to the burner may not produce a sufficient amount
of heat at a HIGH setting even with a correct orifice size. Additionally and more
importantly, at the LOW setting the volume of gas may be so low as to allow the burner to
go out with a small amount of gas still flowing causing the risk of explosion.
In limited cases the control valve may be adjustable by an
adjustment screw accessible through the end of the valve stem which adjusts the valve
characteristics. With this type of valve the internal porting can be increased or
decreased as appropriate.
Finally, the meat of it all!
If you are interested in converting your grill, the best place to start is to
contact your manufacturer or the dealer where you purchased your grill to assure