we are removing a load bearing wall of a stick built house it is an 18 foot span. We are going to us 2) 2x12 LVLs is this enough or should we use 3. the roof is not supported by the walls.

The company you are buying the LVL's from should have the specs for deflection and additional information dealing with this.

I used 1 24' LVL for a 20' clear spread(9 in all across 40')(a 20' X 40' room)no or extremely small deflection and they have been in for 5 years now.

If the roof isn't supported by the walls, what is the load?

KBC

So is this a gabled end wall, one or two stories? We problably need more info but KBC is right about using the resources available through the LVL company. Short of a structural engineer they are about the only folks who can tell you what to use. I do not presonally calculate loading of wall, I ask the suppliers.

Yea get pro help on this, it is a long span. A house is not worth a $1000 mistake