I'm considering installing a battery back-up with inverter to power my AHS Coal Gun in the event of a power outage situation. What is the maximum wattage (or amperage) of brief surge I might encounter if the unit fires with both the 1/2 HP fan motor and the 1/20 HP (I believe) ashing motor initiating simultaneously?

The unit I purchase would (in addition to the above) also need the additional capacity to open and close my 4 Taco zone valves, power my Taco 4 zone valve control module, and power my Taco 1/20 HP circulator. These items would be powered off of one receptacle from the inverter and the boiler would be powered from another receptacle on the inverter (but either way they are all pulling current off of the same inverter at the same time).

Will a 2000 Watt rated pure sine wave inverter with momentary (1/2 to at most 1 second) 4,000 Watt surge capacity be sufficient? Or would something more along the lines of a 3000 Watt pure sine wave inverter with 6,000 watt momentary surge capacity be needed?