All the Yamaha generators our website (even the tri-fuels) are for natural gas and low pressure propane. These can use both fuels because they use the same low pressure engine regulator. The Drawing above illustrates a generator installed on the low pressure side of the house pipe system. The meter shown on the left would be a low pressure propane regulator if this was a propane system.
The Yamaha engine regulator installed will accept up to 14″ of water column maximum. This allows it to be used for both natural gas (4″-8″) and low pressure propane (11″-14″). The same engine regulator can be used for both fuels that is also why they are installed on the tri-fuel generators.
(28″ water column is equal to about 1 PSI of pressure )
Due to these relatively low pressures, somewhat larger pipe sizes are required to handle the load. For instance, a 1/2″ pipe coming directly from a natural gas meter could not be over 10′ long and handle the volume of a generator over 12hp. So having the 1/2″ pipe at the opposite end of a home will need to be just off a larger main pipe line. For instance, if a gas grill outlet is stubbed out the 1/2″ pipe would need to be fairly close to the main 3/4″ or 1″ gas line. This is a very common hook-up request and if the overall and stub out pipe is sufficiently sized removal of the 3/8″ gas grill quick disconnect and shut off would be necessary. Install a 1/2″ tee and reinstall the grill outlet parts on one side and a new 1/2″ quick disconnect (QDC-12) and shut off valve on the other. If no properly sized outlet is available the generator may have to be connected right after the meter or low pressure regulator. Some customers have opted to order a quick disconnect and a very long hose like 75′ that they can roll out and connect to the meter when the generator is needed and roll back up and store when the need is over thus saving the cost of a plumber installing piping. We can provide our custom hoses at any length you may require.
The chart below is a reference guide to help determine the correct pipe size if teeing in at the outlet side of the meter. (Note: This is a guide only. Qualified personnel should calculate exact requirements.)
Though a generator may need 3/4″ or larger pipe to the generator, a 1/2″ hook-up hose us usually sufficient if kept short.
We suggest that you seek the help of your local gas company or licensed plumber. Always check local codes for final installation.