Railcraft steam boiler and Buildcraft gates?

[Westingham]

I had the idea of connecting two iron tanks, one full of fuel and one full of biofuel, to a steam boiler with the purpose of using the fuel only to get the boiler to max steam capacity and then switching to biofuel to maintain everything. Steam is a liquid, so I figured the gates would be able to tell me when the steam boiler is full; the only problem is that the steam boiler would then contain three liquids.

Is this idea going to work or am I back to the drawing board?

 

[HeffronCM]

Boilers are best heated up once and kept hot forever. Since you only want to make the switch once, I suggest doing it by hand.

If you must automate it, I'd do some creative testing and stick a diamond gate next to the boiler tank and the firebox to see what kind of settings you can get.