I looked online and found some information:
ACRYLITE GP acrylic sheet should be heated to between 340° and 380°F (171° and 193°C).
ACRYLITE FF acrylic sheet should be heated to between 290° and 320°F (145° and 160°C).
That's pretty hot. Hot water wasn't mentioned in the instructions I found as a bending method.
Also:
Never heat ACRYLITE acrylic sheet in a kitchen oven. Acrylic sheet gives off highly flammable fumes when decomposed by overheating. These gases are potentially explosive if allowed to collect in an unventilated area.
Most kitchens ovens do not have accurate tem- perature control. Temperatures can be off as much as 75° (42°C), possibly allowing the acrylic to overheat.
And because air is not forcibly circulated in a standard kitchen oven, the fumes will accumulate. When they come into contact with the heat source, there is likely to be an explosion. Repeat: Do not heat acrylic in a kitchen oven.