Adding DHW and rebuild of hot water system

I live in a one hundred year old house in Wisconsin. It is a big old house, the main part of the house is about 4500 sq ft. It has seventy six single pane windows. There is a 1700 sq ft third floor that is currently unheated. I might want to do something about that some day. The house has a new (1997) addition about 800 sq ft, we use as a home office. I added some slantfin to the office, otherwise it is heated with a gas fireplace insert. The kitchen is good sized and is heated by a freestanding gas stove. It has a poured concrete floor that is about a foot thick over a garage. I would really like to put radiant floor heat in the kitchen some day.



So I guess that is the lay of the land. In past years I have heated the house with bio fuel. But this year the bio fuel boiler sprung a leak. We tried to switch to gas, but the gas boiler had not run much in the past few years. When we tried to fire it up it didn't run consistently. We decided to take advantage of the rebates this year. We bought a new Munchkin 140,000 but boiler.



When we got the boiler, I pretty much just plumbed it in. It was about -10 and even with the gas and wood fireplaces running the house was dropping about two degrees every hour we were offline. So it was sawzall time and then I just plumbed it. We limped through the winter getting some convection into the main house zone when we ran the office zone. I am sure it wasn't the most energy efficient setup. But we made it to spring. Now I would like to re-plumb the whole thing.



I am just about to buy a HTP SuperStor DHW that I would like to tie in. I have been picking up zone valves on Ebay and got a good deal on a Taco ZVC406-EXP zone control the other night. I am thinking of building the zones with the zone valves even though they might not be hooked to something right away. And, from what I understand, I can add a second zone controller for those zones in the distant future.



I would like to start with four active zones. The main house, which is going to be a huge zone. Zone two, the office. Zone three, the garage under the office that I would like to put some slant fin into and keep it above freezing. And, zone 4 the garage under the kitchen that I would like to keep about 50 …because my Harley likes to be nice and warm. :-) Makes it more comfortable to go down and sit on it and dream about the summer too. Now that zone will only have one large cast iron radiator so I am a little worried about short cycling.



So I think I have a fair handle on what I am doing. I have three pumps in the current system and I think I can do the new setup with three pumps. Are there things I should be considering? I made an initial design that included a differential pressure bypass valve, but talked to a guy who knows a lot about this stuff and he felt they are expensive, trouble, and not needed on a well done design. …But, was a little sketchy on what constitutes a better design.



From the picture, think about if I added one more pump in front of the DHW which I forgot to put into my design. What are your opinions?



--ja