# Sizing the circulator pump

Today my plan is to size the circulator pump from the chip boiler through the manifolds of the existing oil-fired boiler.  The formula is: Q = h/(Cp*p*Delta T) Where Q is the heat transfer in Gallons per minute, Cp is the specific heat capacity, a constant based on the fluid, in this case water, p (really rho, I need help figuring out how to add greek letters and subscripts) and an assumed temperature drop or Delta T.  Since it is my intention to run the chip boiler at 180°F and set the min temp on the oil burner at 130°F this will give me a 50°F temperature before the temp of the furnace requires it to fire.  By leaving myself enough room I am hoping the Arduino controller and good temperature monitoring will preclude the oil boiler from firing.  For the formula however I am going to assume a temperature difference of 20°F.  So, again assuming a 30,ooo Btu chip boiler,  a Cp for water of 1 BTU/Lbm/1°F, p (rho) the density of water, 62.34 lb/cu ft., Delta T=20°F and to convert BTU to gal/min 7.48 Gal/cu ft  Therefore Q=30,000(7.48 gal/cu ft)/((1 Btu/lbm/1°F)(62.34 lb H2O/cu ft)(60 min/hr)(20°F)=2.9997 GPM

http://www.engineeringtoolbox.com/water-flow-rates-heating-systems-d_659.html

This formula gives the flow rate and now I need to calculate the pressure drop or head loss.   The formula for this is:

#  1. helpact250 says: