Emergency heat from backup generator?

Anonymous Poster · Mar 1, 2002

This is totally hypothetical. I am not planning to build something like this. But it seems like you should be able to get backup heat and electricity for not much more than electricity alone. Maybe I'm underestimating the cost of a usable heat exchanger.

I know it is theoretically possible, but I don't see anybody selling a system to provide emergency heat and electricity from the same engine. How come? Is there simply no market? Or are there too many safety issues that are hard to deal with?

A small air-cooled engine would probably need a heat exchanger on the exhaust. This might lead to a significant risk of exhaust gases escaping into the home air space or heating water. Can good design overcome this?

I know the US military sometimes uses diesel generator units that are cooled by directing water through a heat exchanger in lieu of the normal coolant to air radiator. They can then dispose of the water however it is practical. How about a system like this to run a heat exchanger inside the house? Then you would just need enough electricity to run the furnace blower or circulating pump...

RonL · Mar 1, 2002

Rubintropfen

This is the concept behind co-generation. On a small scale, a would think that you could put a tee in the line between the water pump and radiator on a water cooled generator. Divert it to an inside radiator during cold weather, divert it to an outside radiator during warm weather. There may be a concern with antifreeze, but this does not seem to be a concern with motor vehicles. This would seem to be a simple setup.

RonL

Anonymous Poster · Mar 1, 2002

In today's world, it is probably against some government regulation to do with an air cooled machine, due to possible carbon monoxide poisoning.
In 1950, Onan made the 705 model that ducted outgoing cooling air around the exhaust. I have a 705 trailer mounted, and it melts a lot of snow with the waste heat.
A water cooled machine 6 cylinder ford engine in a 40 foot round room, 12 feet high with no insulation, gives off enough waste heat thru the radiator to require a 2 foot square air duct for cooling.
The rough figure on waste engine heat for cogen purposes is 40%.
You could make up a heat exchanger for a water cooled machine, and pipe it to basebaord radiators. The problem would be you'd also need a radiator on the machine and a valve system to regulate the heat.

Anonymous Poster · Mar 1, 2002

Several different manufactures have built and tested this type of machine. Briggs & Stratton and Fiat both were working on this concept. The designs I have seen are used for primary heat in a house. The engine/generator replaces the furnace and is controled by the house thermostat. When heat is required the engine starts up. The engine heat is used to heat the house and domestic hot water. The electricity generated powers the house with the surplus feeding back into the electric supply grid. This runs the electric meter backwards. In the winter months when lots of heat is required enough extra electricty is generated that you get a check each month from the power company. In the summer months it only runs enough to heat your domestic hot water and you still need to buy electric power.
There was a company in Mass. that was prototype testing these type of units in houses in New England a few years ago. Initial cost was around 7-8 thousand.

Whenever they are available I am ready.

Andy

Anonymous Poster · Mar 2, 2002

Along those lines.....I have talked with a vendor of diesel generators that has a customer in the southern tier. The customer runs the generator once a week in the warmer months and twice a week in the winter. While the generator is charging his battery bank, which provides his electric for the week, the heat from the diesel is stored in a large (=> 4000) gallon water tank..insulated and buried. This provides him with his domestic hot water as well as the heat for his radiant floor heating system. Don't know how many heat exchangers are in the system. The customer seems to be content (according to the dealer). According to the dlr the dwelling is 2 BR, 1 Ba, LR/DR/K room.