Ok, I've been around here since 2007. I've owned a outdoor wood boiler for 10 years and ever since I've read about adding heat storage I've been fascinated by it. The only problem is everytime I start reading about it and how to set it up I just get confused on how to set it up. My current set up is a primary/secondary piping and works great. My outdoor wood burner is a unsheltered type and is 40ft from my house in a 8'x12' shed. My primary loop goes from my shed to my house and over to my shop and back to the shed. I have a Taco 011 pump on my primary loop that runs all the time. In the house I have a side arm heater on the primary loop heating my electric water heater. It then runs over by my forced air LP furnace where I have 2 tees 6 inches apart with a Taco 007 pump on one tee controlled by a thermostat and a heat exchanger in the plentum. I have the same setup in my shop but don't use it much in my shop. This was all designed by a guy that designs heating and cooling systems for a living. My house is 1100 square feet and my unfinished basement is 28'x28'. I've come to the conclusion that I would need at least 500 gallons of storage to make it worth while. My boiler is a pressurized system and I'm thinking of making a wooden heat storage tank with the proper liner that is unpressurized. I've seen many storage tanks built this way and looks like the easiest setup to build. There is no way I can get a 500 gallon propane tank in my basement. Plus if in the future when I'm older or whatever and I decide not to have the boiler setup anymore it would be easier to remove it. So after all this babbling about my current setup now comes the question. What would be the simplest way to plumb a wooden rubber lined heat storage tank into my system? I seem to think if I build a copper piped heat exchanger and install it in the unpressurized tank then just plumb it into my primary circuit. Why wouldn't it work? I really want to batch burn has I can see all kinds of positive things about it. Like I said, I understand heat storage and how it works and I can see the advantages of it, but I just can't figure a good, simple, and cheap way to plumb it into my system.