1740 sq ft house on one loop of baseboard heaters in series

[Verton Miller]

I am a plumbing contractor, not a heating professional. However, I am trying to help out a friend to convert his baseboard heat source from outdoor wood furnace to an on-demand tank-less water heater. His 1740 sq ft house has been heated with 38 total linear feet of baseboard heaters all connected in series. No return line until after the last baseboard heater. So all the water has to flow through each heater and the complete line is only 3/4 inch copper. Room temperature is somewhat controlled by opening or closing the baseboard heater registers on top of each unit. My friend estimates that the total loop may be 300 feet. The old pump is a Grundfos UP15-42F with about 15 GPM and 15 ft of head. With this much resistance, I assumed that I had better order a larger pump to provide enough flow to provide enough BTUs since the Navian 240s provides plenty of BTUs but most likely at a lower output temperature than the wood furnace did. I was thinking a Taco 0011-F4 with a little over 30 GPM flow and 31 ft of head. Now I fear that this may be way too much pump and create a lot of noise at best, etc. Will this new pump work?

 

[Fitter30]

3/4" bare copper at 160* water 32 btu's a foot.
Fin tube 160* @1 gpm 430 btu's
Fin tube 160* @ 4 gpm 450 btu's
1 gpm @325' 52' of head 12 90's
at 4 gpm head really jumps
430 x38'= 16300
262x32= 8384
Something isn't adding up

 

[Sponsor]

 

[Verton Miller]

3/4" bare copper at 160* water 32 btu's a foot.
Fin tube 160* @1 gpm 430 btu's
Fin tube 160* @ 4 gpm 450 btu's
1 gpm @325' 52' of head 12 90's
at 4 gpm head really jumps
430 x38'= 16300
262x32= 8384
Something isn't adding up

I'm sorry, it was 38 linear feet of width of windows which should have been given in sq ft of windows, roughly 4 times as much. The linear feet of baseboard heaters was 64.