I have turned the four steam valves with the wrench and am now unsure of what to do next... could you please tell me what to do next.

right, since you have wrench, I'm assuming you know how to get past the monster and such...basically all you have to do is start from valve 3 and 4, turning them on...this will block your path to valve 1 and 2 but if you have unbolted all the doors on your first trip to finding the wrench then there is an easy access door

however it means going past the tentacle towards the room with the corpse in it...careful since the tentacle is now active so count it's strikes before you move

eventually you will come to your door that will lead you right back to the start...now turn valve 2 and then valve 1...with all valves active you can now leave but you will to find a way to ignite the flame...this is simply pressing the button on the doors that are damaged

take note that the doors will blast off so stay in one place, in other words once you touch the button...do not move since you can easily die or be badly injured when the doors blast off

once this is done find a door that enters into a temple

edit: for further and easier instructions Here is a FAQ