Whole House Surge Protector,HVAC Surge Protector, 200K Amps(SCCR),100KA(Surge Capacity per Phase),Single-Phase(or Split Phase),3-Wire for 120/240V

You have no clue what you are talking about. Surge protectors are always in parallel with the circuit, clamping down on any transients. 270kA looks like a lot, but if the clamping voltage is only 18-20V, is in line with capabilities of a normal surge protector: https://www.amazon.com/Protection-Device-Outdoor-Single-Phase-Capacity/dp/B0D2W46FJ3