Two things to check first:
Do you have the leads to the heater installed into the H1 and H2 slots? That is a difference, as you pointed out, and the heater goes to those two connection points. That means you will have to make a jumper which skips the H2 as you set your IQ board up to run on 110. Cut out the center peg on one of the two three-peg jumpers included in your new IQ and jump from 1 to 2, skipping over H2. Then the other jumper goes in just as it was on the old IQ. I think it's 3,4,5, but verify that.
Next, see if you need to put a jumper on the "press Sw" pins on the top of the mother board - if you heater doesn't have a pressure switch, you will need to jump the pins. The jumper may have been shipped with the IQ box, if not, jump them with anything to test, then order a jumper (or make one).
Let us know how this goes...
HTH
