Originally Posted by ajeismont
Yes. Extract brewing. I've used two kits from my local brew store (an amber and a belgian wit). Each time, I've boiled 1.5 gallons of water with hops for 60 minutes. Cooled with my wort chiller. Mixed with 3 gallons of water. Put in fermenter and topped off.
Could it have something to do with a partial boil vs full boil?
Only indirectly. Since you're using XXX amount of extract, and ending up with XXX amount of wort, it's not possible for the SG to vary. The sugars are there, and don't go away.
It's more likely that adding the top off water to such a thick (1.5 gallons would be very syrupy thick!) wort just didn't mix up well.
It's no problem, really, except that your OG reading is incorrect.
As an example, if you used 6 pounds of liquid extract in 5 gallons of liquid total, then the OG has to be 1.043. It has to be, and any other reading is just wrong.