I put in a diesel standby a few years ago, got it before Tier IV/DPF was an issue for these mid-power standby systems. Mine is a 40KW powered by a 3.3L Mitsubishi turbo with a 60 gallon fuel tank and I have additional diesel storage. It is mounted in a basement area of the barn which protects it and keeps it from dropping to ambient outside temperature; hot air from the radiator is ducted out a window.
I went with an ASCO commercial auto transfer switch that has a programmable timer that allows the generator to start and warm up for 4 minutes before it transfers the load, most standard units switch over 3 to 6 seconds after the generator starts which isn't great for a cold diesel engine although this has temperature controlled coolant and oil heaters. The delay also gives time for the compressors in the refrigerators and deep freeze to equalize before power is reapplied and the transfer switch does an in-phase transfer when commercial power returns. The capacity is a bit overkill but I liked the features of the 40KW diesel (direct injection, mechanical pump and governor with electronic fine tuning of RPM via the autostart/engine controller better than the available 30KW versions.
It sips fuel at my typical load but has no problem running the deep well pump, two electric water heaters, etc. Biggest issue was getting a good load on it for break-in and I was running both central AC systems along with some space heaters plugged in and showers running to load it to 65% of continuous rated power
The TS switch sends a start command to the generator controller after 3 seconds of commercial power failure and once it reads correct voltage and frequency from the generator, it starts its 4 minute countdown timer before transfer. It does a monthly 25 minute exercise cycle under load to ensure it is ready to go when needed.
It definitely beats my old method of going to the barn and starting the portable gas 10KW generator and wheeling it to the house and flipping breakers (generally in the middle of the night during heavy snow!). Now I can just look out my bedroom window and see the status lights on the transfer switch knowing that in a few minutes the lights will be back on while I stay warm and dry inside.
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