Its not realist to try to run a 16KW generator on a 100 Lb tank.

A 16KW Generator uses 320,000 BTU/Hr @ 100% load

A 100 Lb cylinder has 2,189,600 BTU maximum capacity. So, in theory, it could run the gen at full load for 6.84 hours.

However, you have to consider the vaporization rate of a 100 Lb tank which is 79,700 BTU/Hr at 60°F, 52,400 BTU/Hr at 30°F, and 25,000 BTU/Hr at 0°F.

The previous owner probably had an above ground tank...maybe 250 gallons. They would likely have had a first stage regulator on the tank to convert the tank pressure to 10psi. Then a second stage regulator at the house to drop down to about 11" water column of pressure to run the gen.

That may be the second stage regulator in your photo. I also see what looks like CSST in that photo (the yellow piping) which is not allowed outside. I am not seeing enough of the other pipe there to tell what it is.

 

Maybe you could find some realtor pics that show what size tank was there prior to removal?
Nonetheless, It might be in your best interest to contact the original generator installer or local installer for a quote on what is needed to hook up safely and legally.
How many hours on the unit, or how old is it? Chances are that it is obsolete or close to it....

 

Maybe you could find some realtor pics that show what size tank was there prior to removal?

The previous owner may have had multiple 100 Lb tanks (like maybe 4) manifolded together. That would provide about 90 gallons. If the ambient temperature is warm, that would provide about two hours of runtime at 50% load. A lot of assumptions there.

 

Is there any warranty left on this unit, by serial and model numbers? If there are, and you care about getting warranty service, then you'll want to download the "installation manual" for the model number.

It has all the details on hooking up propane and/or natural gas. In turn, the propane or natural gas supplier(s) in your area will be able to provide service, up to and including the correct type of regulators needed to feed that Generac.

Anything else, other than the above, and the warranty will not be honored by Generac or any authorized service techs. If you are going self-supporting, or this is a test scenario, and will never need warranty service, then you could cobble together the necessary high-btu regulators, hoses, and connections, per the pictures in most Generac installation guides, leading to whatever size tank or service you decide will meet the generator's demand. The burden is on you to meet the high flow demand from the Generac, as otherwise it will throw fuel-related errors.

Having a propane service come out and set a tank (you can usually rent this), fill it, and provide the necessary piping & regulators all the way up to the generator, would be the easiest route to go.

An authorized generac dealer could send out a tech to review the unit, and determine what will be needed to get it running again, including the fuel considerations.

Hope this helps ...

 

I am not seeing enough of the other pipe there to tell what it is.

I just realized that is PVC pipe which is needed to get the regulator's vent away from the ignition source (the generator) when the regulator is located close to the generator. I think most codes say five feet is needed, but that may vary with your local code.