Spacer system for installing vacuum insulated glass (vig) window unit in window frame designed to accommodate thicker ig window unit

A window unit comprising:

• a VIG window unit in a window frame, the window frame capable of supporting a non-vacuum IG window unit having a larger thickness than does the VIG window unit,
• said VIG window unit comprising first and second glass substrates with a low pressure gap provided therebetween, the low pressure gap being at pressure less than atmospheric pressure;
• the VIG window unit being directly supported on a first major side by a first stop portion of said frame and being indirectly supported on a second major side by a second stop portion of said frame, so that a spacer is provided on the second major side of the VIG window unit between the VIG window unit and the second stop portion, but no similar spacer is provided on the first major side of the VIG window unit.