I just experimented with the copper tube heat exchanger and my little HHO torch and it does produce a fair amount of heat. I got the tubes to 160 degrees in about 20-30 minutes with a 1 inch flame. and when you lightly blow through the tubes it puts heat out the back of the pipes. I like the heat exchanger. Simple yet effective!   

Ramset,
What produces poisonous gas? I've never heard anything about burning hydrogen and giving off poisonous gas. With some simple mods the system could be vented. 

PMAZ

If you use an electrolyte  you are not using pure water

And you get poisons

Yes venting is required

Chet

@hartiberlin,  as i sad, i needed about 260 Watt for about 3 liters.
I can produce the gas with my drycell which i introduced in the "Drycell goes to Austria" thread.
I wrote there in Oktober, that the cell reaches values over faraday.

For this heater, i already cutted some copper tubes, to try it out. I will write soon about the exteriment.

@ albator 10, in the copper tube there is just steelwool, ( it should be bronzewoll but i could not find that) very pressed, and a little bit of water,i saw this in a video at youtube, and it seems, it works, you would need about 3 liters of gas /min. The more gas the better. I have two bubblers für security reasons.
You can find hundreds of videos at youtube

All the link to Woodpeckers thread

          http://www.overunity.com/index.php?topic=5788.40;topicseen

                        Chet