I recently purchased an old Jensen 24b 100,000 btu wood boiler, I need to hook it into my system. I am heating about 1800 sq. ft. with baseboard heat. I have a Weil-McLain VHE propane boiler with 2 zones for the house, 1 for the garage, 1 for the 40 gal domestic hot water tank. I had originally planned to plumb this into the the return line/ boiler feed water. In essence, feed the return water through the wood boiler, so that when it hits the propane boiler it is already at temp and should the wood boiler go out, the propane boiler would just kick in as normal. However, I feel this will subject my system to alot of scale/corrosion from the old steel boiler. So I am now considering using a heat exchanger and having the boiler on its own small separate loop. Still feeding the return from the house into the heat exchanger and then into the propane boiler. The wood boiler would simply run on its own loop and provide hot water to the heat exchanger. Can somebody tell me which way will work better and/or be more efficient? I am not an Hvac guy and I am a little overwhelmed on which way to go.