Looking for some input on distribution

First I'll give you an answer on running low temp baseboard, from my own 6 year experience with standard hi-temp baseboard distribution and a wood boiler. I run without storage, but have become very familiar with, and am highly aware of water temps. I have a number of thermometers on various pipes, and have come to "think" in terms of BB water temp. On many less cold days we run the boiler more like a wood stove, and frequently have a small fire going which produces water temps of 150-170. Having been through every possible variation of weather condidtions, I can tell you for certain that if the BB water temps are matched appropriate to the heat requirement, these lower temps will heat the house just as effectively as 180-190 temps will on a cold day. And the heat requirement varies constantly. As I write this, it's 14F outside but with full solar gain. The the BB water temp is currently 155, and the house is at the typical 73F that it almost always is. With full sun today, I'll shut the boiler off for a few hours, and then later relight the fire and produce water temps of 170F or so for a short period of time. But tonight the boiler will have a good fire and send the 180+ temps that will be needed througout the upcoming cold night.

Next, I'm wondering why you are planning on making extensive changes to your distribution system, before having any experience with your new wood system. It's hard to determine from what you wrote exactly what the current problems are (if any). You wrote: "Current setup is two zones which seem grossly out of balance". But what is the actual heating situation? Are some areas of the house too warm, and others too cool right now? I suggest that if you have no major problems (other than paying for oil), why not leave your currently distribution system intact, and get a year's experience running with wood heat. Your learning curve will be mainly when to recharge storage, and what temp to bring it up to. And this will be determined by how low the storage can go and still heat the house adequately. Every day is different, and there's lots of trial and error before you completely get the hang of it.

I'm not questioning that your proposed change wouldn't be better, but will it really be necessary? And again with radient; based on near universal opinion, is superior to BB. But the question is will your actually need it? Now if you simply want the better comfort of radient, and have the $$ to get it done, then that's a different story. But that consideration aside, I'm thinking that perhaps your current system may do just fine, once you no longer have to constantly keep the temps turned down in order to burn less oil. Your heating pattern is likely to change (for the better), once you are burning wood. Not trying to be critical of your plan - just giving you a perspective of what changing to wood heat can mean to you.

Have you considered replacing with an Alpha, or other ECM pump? The auto detect setting is usually the best of all worlds.