Well it's definitely putting out some good heat if its adding 40° to 50° to the incoming water during use. I tend to agree that the pump is probably putting some decent flow through the pipes, given the even inlet/outlet temps. Either way, it's an excellent retrofit for an old wood or coal stove. Definitely do-able on mine. I might have a go at it when I get some extra time and cash, just for experimentation purposes if nothing else.

do you have any other parts to the system for safety? what happens if the pump fails to come on? do you have to worry about a steam explosion or does something deal with the pressure?

It has an expansion tank built into the line. Also the fill is just a large pipe with a loose fitting cap.

I believe it does actually 'boil' the water out of the loop in the stove until the pump kicks on. You then hear the pipes pop alittle when the water flows into the pipe, but after that the system runs normally and very quietly.

No problems so far anyway...:D

I also got a line on a 75K BTU Carrier gas boiler with expansion tank, pump and 2 zone valves for $200. I hope the guy saves it until the weekend, can't get over to give the cash until then. I think that might work well for the house and/or garage for my "Plan B" back-up heat.

Then I can tell the city to take me off the hot water heat!:thumbup: Next step would be working on the electric then. Off the grid in town is the goal.

The expansion tank is only for minor variations in pressure. As strider was trying to suggest, if your pump failed (and there are so many reasons that this could happen) you would have a very serious situation on your hands... We don't hear much about steam burns anymore because we don't use steam much anymore. But my mother, who was a country doctor's assistant in the time when steam was in use, had some pretty grizzly tales about steam-power gone wrong... we're talking about arms and hands and fingers being cut off by high-pressure steam, and blindness and large areas of scalded skin.

You ought to be able to find a pressure relief valve from an old water heater... there is a reason they are required.

Safety isn't just for sissies anymore...

-AC_Hacker