CHP
COMBINED HEAT AND POWER
So what is it?
Basically it's is an efficient technology for generating both electricity and heat. In a CHP plant, heat and electricity are generated simultaneously in a single process.
With a Listerclone and ST generator set up it is possible to capture as much power/heat as possible by using a renewable fuel such as vegetable oil which is classed as carbon neutral.
The engine by burning / combusting the fuel produces heat. This heat comes along in two forms, coolant and exhaust. The engine runs most efficiently at about 90oC. The exhaust temperature can vary between 300 to 400 oC depending on what the engine is being asked to do via the electrical load on the ST generator. It's simple really, more power required = more heat generated.
This coolant heat output from the engine can be boosted even higher by fitting a heat exchanger on the exhaust therefore getting as much heat as possible out of the power plant. You then use this hot coolant for home heating or heating water up.
Another good place to go for an explanation is Wikipedia
Home heating.
Simply couple up this supply of hot coolant to your existing central heating system .I know it's not quite that simple but that's the idea. There are a variety of methods used for coupling up. First thing you must remember is that the engine has coolant in it that has antifreeze added for obvious reasons therefore your central heating water will have to be drained and antifreeze added unless your Listerclone is in a place where it doesn't freeze.
Basic Set Up
Find the nearest point of your central heating pipes, both feed and return to your boiler. We'll start with the return pipe. Extend this to the output of your "power plant" whether that is direct to the engine or onto the exhaust heat exchanger it doesn't matter. Now the feed pipe, a little more required here. Extend this to the input to the engine. On the way you must fit a standard central heating pump before the engine ,you want to keep the pumps temperature as low as possible to avoid overheating problems. In order for the engine not to overheat a thermostat must be fitted some where around, on or in the engine output pipe. This will be the type such as fitted to car radiators so that when the engine comes up to operating temperature the pump is turned on and cooler water is pumped in. In a car it would turn the fan on. This addition to your home heating system must operate independently from your existing boiler controls to ensure your engine doesn't overheat. When first started the pump will be on and off quite a bit as the whole system warms up. As you get used to your set up you may find that extra heat is needed in the house so just put your boiler on as normal. The engine will then be acting as a supplementary heat source, your boiler will just "see" warmer water coming back for reheating therefore it won't be on for as long as it would normally. You will then be saving money by using your engine and of course your generator will be supplying all the power for this. So what happens when it gets warm or even hot ?A bypass system must be fitted which is quite easy to do. Get a car radiator ,a big one with a fan, mount it outside somewhere near to your engine and feed the hot coolant there instead of your house for cooling down. A couple of valves and "Tees" in the feed and return circuits will accomplish this. All of the above is pretty basic plumbing but if you don't know how to do any plumbing, well maybe now is the time to learn a few new skills (or get a plumber in). You can adapt this circuit quite easily to heat your hot water in summer, doing it in theory is easy but in practice requires more time and resourcefulness as the hot water tank in most cases is miles away from your heat source. So you then use a standard immersion heater in your domestic hot water tank supplied with power from your ST generator eliminating the need for any complicated plumbing.
Water pressure and engine head gaskets
Lister type diesel engines are designed to be run at atmospheric pressure not a pressurized system such as found in a vehicle engine. It has been proved that if your header tank, also called the expansion tank, that your central heating system is connected to is too high it can cause the engine head gasket to blow. This has occured with three story houses so please bear this in mind when designing your setup. To get round this problem a method of heat transfer is required such as a water tank. A diagram of how to get around the pressure problem is shown below. The central heating type pump circulates the water in the tank to distribute the heat and stop the immersion heater burning out. You might think this is an incorrect way to use the pump but it will not "suck" the hotter water at the top of the tank and pump it into the bottom.