ok, generac is only a manufacturer. They dont install. Anyone can install. Problem is most installers dont service them, even during warranty periods. Better make sure you have a maintenance company thats willing to drive to your place. There are far fewer service tech for liquid cooled units, and even fewer for diesel. You need a true diesel mechanic experiences and training for the large diesel units.
I really have no idea if these generac units, or any other branded diesel units will run on fuel oil. You need to check into that.
#2 heating fuel oil and #2 diesel are approximately the same BTU/gal, and viscosity; where they may differ is in the respective additive packages, as heating oil fuel
tends to have more additives geared toward prolonging storage life, and #2 diesel fuels
tends to have more additives towards ensuring that the cetacean # and lubricity are at the minimum for diesel #2 or better, along with more anti-corrosion and anti-deposit additives. However, "tends" is not the same thing as "is". I know of many parts of the country where heating oil and off-road diesel comes out of the same tank at the distributor, so YMWV.
Heating oil vs diesel explained for homeowners, including key differences, costs, safety factors, and when limited substitution is possible
www.elanfuels.com
Lots of folks use one for the other, and in some parts of the country they will be identical, but that will depend on local usage, regulations, and demand. All of New England went for the ULSD standard of sulfur as the definition for heating oil in 2016.
If it is a new generator installation, the generator manufacturer probably has an opinion on allowed fuels.
For the generally limited hours on a residential grid backup generator, I am not sure that I would sweat the difference, but everybody is different. For dedicated, sustained off grid use, I would be adding in additive packages for diesel use.
All the best,
Peter
