I've had it for about a year now, and I used to play for about 4 hours each time Id play but now it heats up after an hour of gameplay. Will this effect the ps3 in any way?

This is why you should've gotten an XBOX 360

have you been cleaning the dust out every few weeks ? or letting it build up inside ?
take a vacuum to the vents every month or so , keep it clean
also make sure it has 4 inches free space all around or more to vent and is in a cool spot on a flat surface made of wood ort glass , not enclosed in a cabinet

ps3 manuals tell you proper care instrucions such as these

it broke dont touch it . you might need to get a new one or get it repaired