How to Use Your Tri-Fuel Generator with Natural Gas: A Guide

Power outages are inconvenient. Insightful, right? But having a reliable generator can make all the difference between riding it out in comfort or sitting in the dark wondering when the lights will come back on. If you've invested in a portable tri-fuel generator, you're already ahead of the curve. These versatile units give you the flexibility to run on gasoline, propane, or natural gas, which means you're not stuck scrambling for fuel when everyone else is doing the same.

One of the most common questions we get is "How do I connect my generator to my natural gas supply?" The short answer: read your generator's owner's manual! It's packed with useful information about assembly, setup, operation, troubleshooting, and more. Find it, grab a cold beverage, and read it. If you don't have a physical copy anymore, you can find the latest version of the user manual as a PDF on the WEN website page for your tri-fuel generator - just search the generator's model number in the search bar at the top of the page.

For an in-depth discussion with an appropriate minimum of snarky commentary, read on.

Before Beginning: A Note about Standby Units and Automatic Transfer Switches

If you purchased a portable tri-fuel generator expecting it to automatically come on when the power goes out, it very likely will not. Some portable tri-fuel generators on the market can connect to automatic transfer switches (the device responsible for automatically turning on a generator when the power goes out), but many cannot. They'll need to be connected to a manual transfer switch (or interlock kit, in some jurisdictions). Transfer switches safely and legally connect your generator to your home to help eliminate the risk of backfeeding power into the grid and potentially injuring utility workers working to restore power. Go read our handy article on transfer switch selection and installation for more details.

A diagram showing the typical connection of a generator to a home's electrical panel using a manual transfer switch. Natural gas supply not shown.

If any of the following apply to you, then you're probably better off investing in a permanently-installed standby generator, as well as an automatic transfer switch:

1. You live in an area prone to frequent or multi-day outages from hurricanes, snowstorms, or other severe weather.
2. You don't want to bother with setting up a generator every time the power goes out.
3. You're not confident you're physically able to set up or start a generator in the event of a power outage.

Standby generators are designed to deliver much more power (usually 10 to 40 kW) than portable generators, and can be easily connected to automatic transfer switches by a professional installer. When the power goes out, the standby generator comes on, and you're back up and running in seconds.

Specifications You'll Need to Know

Read your owner's manual. It very likely has all the details you need to connect your generator to an NG supply. The specifications you'll need to know include:

• Minimum flow rate. This may be provided at different load levels, or there may be one baseline recommendation. This is usually given in BTU/hr or cubic meters per hour (m³/hr or cbm/hr). It's a measure of how much fuel your generator consumes.
  • BTU stands for British Thermal Units, and is a common unit of measurement in the gas industry. The metric equivalent is about 1,055 joules (J). If you have the nominal fuel rating or heating value (see third bullet point below), you can calculate the SCFH value (Standard Cubic Feet per Hour), which helps with pipe sizing calculations. A certified plumber 
• Minimum supply pressure. This may be provided at different load levels, or there may be one baseline recommendation. This is usually given in inches of water column (in. WC), pounds per square inch (PSI / PSIG, with "G" indicating gauge pressure), or kilopascals (kPa). 
  
• Nominal fuel rating. This is the amount of energy available in a given volume or mass of gas. This is usually given in BTU/ft³ or J/kg. Your NG supplier or utility can provide you the fuel rating of the gas available at your home.

Also make sure you know the size of your home's NG distribution piping. Most homes use 1/2" pipe, but some larger homes, or those with lots of heavy loads on the gas supply, may use 3/4" or 1" pipe. Your generator's owner's manual may have a minimum recommended size. If it does not, or if you're unsure what your home's piping size (or if it can meet the generator's requirements), consult a professional. 

Lastly, when reading your manual, make sure you know the rated power that the generator can provide when running on natural gas. It's likely lower than the advertised rated power, which is usually specified when running on gasoline.

When to Call In a Professional

In some states or towns, it's illegal to connect a generator to the natural gas supply yourself. Make sure that... 

• you talk to your gas or utility company, as well as your local municipality, to see if this is the case; 
• your components, supplies, and installation all comply with all applicable local, state, and national codes and installation requirements. This can include, but is not necessarily limited to, ANSI Z21.54, NFPA 54 and 58 (58 applies to LPG), the National Electrical Code (NFPA 70), etc.
  
• your currently-installed home gas meter and distribution piping are the right size, and can maintain enough flow and pressure to accommodate the generator, as well as any other currently-installed NG loads (such as ovens, furnaces, or other home appliances). Keep in mind that you may be running the generator and other appliances at the same time.

Improper supply sizing is the number one cause of poor generator performance when running on NG.

Additionally, even if it's legal in your area to connect your generator yourself, if you're at all unsure of the process or not confident in your ability to safely connect it, hire a professional, licensed plumber with NG certification to set up your generator. 

Supplies and Tools You'll Need

If you're using natural gas to fuel your generator, there's a good chance you're powering appliances in your home during a blackout. To safely and legally connect a portable generator to your home, you'll need a manual transfer switch (or interlock kit, in some jurisdictions). Go check out our handy guide on transfer switch selection and installation if you haven't already, then come back here. 

At the risk of sounding like a broken record, read your generator's owner's manual for specifics. Generally, you'll need the following:

• An adjustable wrench (or combination wrench of a certain size) to tighten the connections between the various components.
• A natural gas hose to connect the generator to your NG supply. Make sure the hose meets the following requirements:
  • Choose a hose with a CSA or UL certification to the ANSI Z21.54 safety standards for gas hose connectors.
  • Make sure the hose is the right size. Hoses are rated by their inner diameter - usually 3/8", 1/2", or 3/4". Your generator's owner's manual may have a recommendation for the proper hose size. If you're not sure, consult the manufacturer. Generally, 1/2" hoses are suitable for most tri-fuel generators; 3/4" may be required for units rated above roughly 15 kW, or using V-twin engines.

 WEN offers a 25-foot 1/2" hose with solid brass connections, including a quick-connector on one end (part no. TF1450X-1431).

• • Make sure the hose is rated for at least the pressure required by your generator. For example, if the maximum pressure your generator requires is 11 in. WC (approximately 0.4 PSIG), make sure your hose is rated for at least 0.4 PSIG - preferably higher.
  • Also ensure that the hose is long enough to position your generator AT LEAST 20 feet from any and all doors and windows. Practically speaking, this means the hose should be at least 25 feet long. Generator exhaust contains carbon monoxide, which is a colorless, odorless, tasteless, deadly gas. Positioning a generator too close to a home, garage, etc. can lead to carbon monoxide poisoning, which can cause injury or death.
  • A dedicated in-line shutoff valve. Generally, these are quarter-turn ball valves rated for gases, but make sure that the valve selected is approved for use in your area, as well as that it can handle the pressure and flow rate your generator requires.
  • Optional: an adapter to connect the NG hose to the supply shutoff valve. Make sure your hose can connect directly to the supply, or purchase an adapter.
    • You may also need an adapter to connect the NG hose to your generator. It may or may not be included with your generator.
    • Many NG hoses have universal quick-connect adapters that can be easily connected and disconnected from the generator for quicker setup and teardown.

• Gas-rated PTFE tape or joint compound (if specified in your generator's owner's manual, for the threaded connections).
• Soapy water for leak detection.

Keep your setup as simple as possible. The longer the hose or pipe runs, and the more fittings and adapters used, the more opportunities there are for pressure drops, leaks, and other problems that would affect performance.

Generally, you'll connect the shut-off valve to the supply, connect the hose (and any required adapters) to the valve at one end and the generator at the other end, test for leaks using soapy water, turn on the supply, and then start the generator according to the procedures in your owner's manual. However, your setup may be different depending on your particular situation and local code requirements. Follow any instructions given in your generator's owner's manual.

Other Things to Keep in Mind

Unfortunately, all signs indicate that the laws of thermodynamics remain inviolable, and so you may run into problems in the following situations or locations: 

• High altitudes. Most specifications in your generator's owner's manual are likely provided for installations at or near sea level (generally below about 2000 feet elevation). If you live in a mountainous area, aboard an enormous hot air balloon, etc., your generator will likely not perform as well as it would at lower altitudes. It's a good idea to install a high-altitude kit if you'll be running your generator at high altitudes, even if you won't be using gasoline. Your generator is also less fuel-efficient at high altitude.
• Very hot weather. In hot temperatures, the pressure or flow to your generator may increase, and the generator may not perform as expected. Your generator must also work harder in hot weather than cool weather, and performance will drop. On hot summer days, it's a good idea to reduce the load on your generator and to run it in the shade if at all possible.
• Very cold weather. In cold temperatures, the pressure or flow to your generator may drop, especially if you have a long hose or connection between the generator and natural gas supply, simply because of its exposure to the cold air and ground. Additionally, in cold weather, if your home's furnace uses natural gas, there may be additional strain on the utility's NG supply (since your neighbors want to stay warm just as much as you do, and their furnaces may be running too). It's a good idea to have a backup fuel supply for emergency situations.

Conclusion

After reading this, if you have any questions about your setup specifics, we recommend consulting a local professional plumber licensed for NG work, your gas utility, or your local municipality.  If you have any questions about your WEN tri-fuel generator after reading this post, or need help figuring out which generator is right for you, please give us a call at 1-847-429-9263 (M – F, 8 – 5 CST), or drop us a message here to talk to our friendly and knowledgeable technical support team. Thanks for reading!