It lists 13MW constant consumption, but that's a lie. It can consume at most 13MW, AND at most 5 fluid per second. This means with most fuels, it cannot get anywhere near 13MW consumption, and thus not anywhere near 40MW output. In almost all cases you're better off making solid fuel and feeding a regular heating tower.
Oh, and to top it all off, it lies about the consumption rate. It actually consumes 6 maximum. Either the display has a rounding error or it just... consumes 1/second without reporting it to the tooltip?

Alright, I did notice the higher efficiency vs normal heating towers, that evens things out a bit. I also noticed that liquid rocket fuel is part of this mod, and seems to be the intended way to use them, since you can just slap an assembler on the bottom of the heating tower and deliver rocket fuel to the assembler for heat on demand.

Fluid heating towers are also generally worth putting in spots where you already have pipes carrying fuel you'd want to burn, like in petrochemical processing areas.