During heating maintenance I found very low water flow and traced it to an inoperable vs pump.i called tech support and got a case# 450821. Unit not heating o capacity and running heat out of the loop from long run times. Auxiliary heat was also set to 4 degree differential and would never come on. I reset to default settings. All other aspects of the unit are operating normal and unit will be once the pump is replaced. I called Alex to let him know and verify that it is covered under 2 year warranty. I filled out a part orde form. Upon arrival I went to system and shut off power. Removed defective pump and installed new one. Bled all air out of lines. Returned power to system and checked operation. Ran heat and measured specs. Suction pressure 80psi, Discharge pressure 326psi, Superheat 11, Subcool 19, Delta Air Temp 24, Delta Loop temp 6. Unit is within installation spec when entering water temp is 30 degrees. Unit operating normal.