Here is my initial layout for what I built. It seems to work fine for me.
Your setup is close to what I put in last year. My house furnace is in the basement, so it is lower than the OWB so my pump is nearer the low point of the system in the basement and the distance shown on the attachment is about the right distance, Grundfos 26-99 pump, and a 17x22 HX heating about 4000 sf. I put a bypass and drain for the HX since its right after the A/C coil and must be drained in the summer (used ball valves w/a drain on them). Our house is normaly not above 70 in the winter unless the mother in law visits
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I did modify my potable hot water and built a OWB HX bypass for the summer season (not shown on here). I also have an electric demand hot water heater, so no potable hot water storage in my system. I ran the electic hot water heater as a supplement last year, but have just shut it off this year and have never been w/out hot water. The house was full of extra family members at Thanksgiving and I lost track how many showers there were each morning (probably 10 minimum). I think that I have a 30 plate water to water HX. The 1" PEX valve shown in the house return line is the lowest point in the whole loop and why it is there. I figure I can get 95%+ of the boiler water out from that point if necessary. The electrical from the OWB to the house is an empty conduit right now, power comes from my shop elec panel.
On the shop loop, my heated area is 24x56x10 and it is about a 9-foot raise to the furnace HX (18x18 inch) so I ended up installing the pump on the back of the boiler for that application instead of how it is shown here. That pump came with the Shaver furnace and I think its Armstrong's mid size pump (Astro 250?). The 75-foot run shown is longer than as built, I relocated the OWB and it is closer to 50-feet as built. I also did not put the bypass on this furnace since the HX is above the OWB and I don't have A/C there (yet). I installed a vent at the high point and can just drain that part back to the boiler if I ever need to or if I add A/C to that furnace in the future and need to drain the HX in the summer.
I am very happy w/my system. Good luck w/your build!
I did not find this site until after my build and built my own underground lines, 6 wraps of techfoil around 2 ea 1-inch Pex-AL-Pex lines.
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