"Thanks for the Info, but I gave the whole Idea (heat support of our house) because there is too less energy to get an valuable result. You need abaut several kilowatt of power to get an interesting support of our central heating."

"Nowadays I use a simple copper wire. About 10-20m length with 1,5qmm^2 profile. So I have about 1 Ohm resistance. Thats OK for my application. What I wanted to try is to use the brake energy in our heating system to support heating. There came this Idea of the 12V glow plugs up, but they are not very durable."

"Yes I suppose the filaments rust out due to the water contact. They are made for an oily, lubricated environment.

Try to use old light bulbs, preferably ones from a car or truck if your system voltage is 12V. Always operate them below their rating and they will last forever.."

"It is a bowl filled with water. There are several glow plugs (from a diesel car) screwed in the iron skin which i used for electric braking of the generator if there is too much wind. They are absorbing about 200W at 12V level. But the experiment failed. The glow plugs always died after several weeks of heating. Maybe because of the direct contact to the water in the bowl."