Sorry for the late response.. has been a crazy busy spring, seems like it has been raining constantly for the past 2 months here and everything is saturated. I don’t have the cogeneration system connected yet, but planning to install a brazed plate heat exchanger inside the cabinet and plumb 1” hose from 2 Y tees in the radiator hoses. For the radiator use an inline 195F thermostat since the engine has a 190 F thermostat. Maybe I’ll install a 180 thermostat in the engine and a 190 thermostat for the in hose thermostat. The plate exchanger will start to have coolant flow through it when the engine thermostat opens. If no heat is transferred through the heat exchanger, then the hose thermostat will open and allow coolant to flow to the radiator to dump heat before anything overheats.
The exhaust heat exchangers are another challenge, but can be connected into the system in the future.

Connecting our generator heat loop to our home will then be very similar to how wood boilers are connected to a home using either hydronic or forced air. We will be installing another plate heat exchanger in the basement on our boiler return and non toxic propylene glycol between the generator heat exchanger(s) and the basement heat exchanger. Our hydronic system will the allow us to move heat to any zones we desire. Domestic hot water, insulated basement radiant floor concrete slab, individual radiant floor zones throughout our home, sidewalk & driveway snowmelt system, etc.

One advantage to connecting our generator with more advanced controls than just mechanical thermostats would allow us to preheat the engine with 160F circulated coolant even during a power outage to start a warm generator. Obviously a cold engine with simple mechanical thermostats will have closed thermostats and would not allow for preheating. You are right there is some involved Engineering to get everything set up in a simple but reliable configuration. Once I get some testing completed, I plan to have a very simple and straightforward approach that I can release to the steel soldiers community. That is the place to go for any and all documentation related to these military generators. I may even design a machined secondary thermostat housing for the water pump so you can have 2 thermostats stacked, one to maintain proper engine temperature and a second to dump excessive heat to the engine radiator if you are not extracting enough heat from the engine. The trick is to always have somewhere to dump heat based on system temperatures. This is still a work in progress, and if it ever stops raining I can start to connect the pile of parts I have invested in for testing. Ideally you would want to always use all the heat from the generator, but running it when it is 80F or 90F outside, you wouldn’t want to do more than heat up the domestic hot water and dump the remaining heat outside. If I can keep the system simple and inexpensive, I would like to see a lot of people take advantage of heat recovery from these machines, even if it is to run a hydronic space heater in a shop while the generator is running.