Is this transformer powerful enough?

[illusive]

  Hi everyone,
  I'm DIY-ing a soldering station. The soldering iron i've bought is the SP-90B which has 90 watt rated heater. The resistance of the heater at room temperature is about 1.9ohms. Originally i've planned to use 100VA 24AC transformer but now i have second thoughts. I did some basic tests with a 100VA 24VAC transformer - the startup current at 24 degrees is about 8.23A rms, the voltage drops to about 22V rms. As the temperature increases logically the resistance of the heater does as well and the current drops. The target temperature of 350 degrees is reached for 12 seconds at which point the current is about 4.3A rms, and the heater resistance is 4.4ohms. The resistance measurements are taken from UNI-T 139C multimeter, so they can be a bit off, the V and A measurements are from a oscilloscope. I know this is overloading the transformer, but the idea is that that much power will be drawn only for the first 12 seconds at startup. Then just a small bursts of power will be required to maintain the temperature.
  The original station, that this iron is made for, claims heat up time of 10 seconds, but i don't know to what temperature is the iron set up to. The transformer inside looks about the same size as mine 100VA one.
  The soldering station controller is not build yet, so i cannot test the thermal preformance of the transformer under real world usage conditions with the soldering iron, so i was wondering if someone with more experience with power transformers can give me advice.
  Thanks!

[Zero999]

It should be fine. Transformers can withstand short overloads with no problems.

[David Hess]

I agree; it will work fine.  Once the iron heats up, the duty cycle is low.