I have an application that requires 75,000 BTU heatloss. Could I pipe the NextGen Boiler in parallel to achieve this output?

Yes that is acceptable. However, a third party control will need to be incorporated to turn on both boilers. There is no communication output to activate the second boiler. We highly recommend with this option that both boilers are set at the same supply water temperature. Do not use outdoor reset with parallel boiler piping. Another option would be to separate the boilers in zones and bring the PEX piping to separate manifolds located in the building. This can reduce long leader lengths of PEX piping.