Here, I had this problem myself and finally found a solution. Take a peek; I'm assuming you're using Unleashed with that version, which is what I'm on.
Welp, nevermind, I relogged this morning and everything works fine with two adjacent thermal boilers with pump covers. Thank you all anyways!
Inefficient. The Outputs of the Thermal Boilers are one Block too far away from the inputs of the Steam Turbine. A Drain Cover installed before building the Thermal Boilers, set to import Mode would have been sufficient, and would have saved the Machine Boxes.
The only location where you would have needed a Machine Box in 1.5 (1.6 has large Pipes for it), is the Lava Input, and that just because it consumes Lava quite fast.
Drains, on the other hand, don't seem to work, possibly because they would still require a pump on the other side so I'd have to use a dedicated machine block inbetween all the same, I suppose. That or either a pump cover that I can't place. Oh well.