How is the Pre-Heated Exchanger outputting 149 out of 103/s?

Factorio has a few baked-in constants core to its fluid & thermodynamics calculations.
We cannot modify these, so some other things will compensate as a result.

• The game assumes each unit of fluid requires 200 J (Joules) of energy to heat it by 1°C.
• The game assumes fluids will always be input at 15°C.

Is the Pre-Heated Exchanger producing more than it is consuming?

• No, while not shown in the tooltip, an equivalent fluid input/consumption matches the current Output per second (fluid).

What do you mean by "compensate"?

• The game derives an entity's maximum Output per second (fluid), assuming a 15°C fluid, from its Max. consumption (energy), the latter of which we can modify in a mod.
• The game derives an entity's current Output per second (fluid) from the rate at which energy is spent heating that fluid.
• If an entity cannot spend the entire amount of energy per unit of fluid, it will process units of fluid at a higher rate to compensate

"Derives"...how?

• For example, the vanilla Boiler heats from 15°C to 165°C, requiring 30kJ per unit of fluid.
• Its Max. consumption (energy) is 1.8 MW, aka 1,800 kW aka 1,800 kJ per second.
• Maximum Output per second (fluid): We can divide 1,800 kJ/s by 30kJ/unit of fluid, giving us 60 units per second.
• Current Output per second (fluid): Our input fluid is indeed at 15°C, spending its allotment of 1,800kJ/s to heat 60 units of it.
• The tooltip confirms this when running normally: 60 out of 60 steam per second.
• The same for vanilla Heat Exchangers. If you substitute 165° with 500°C, and 1.8MW with 10MW, you arrive at 103 out of 103/s

And as for the Pre-Heated Exchanger's 149 out of 103/s ?

• Our modded entity is also set to 10MW to match the regular Heat Exchanger for similarity reasons.
• Bear in mind its input fluid - steam - is not 15°C, but 165°C.

Maximum Output per second (fluid):
- Assumed input fluid temperature: 15°C
- 500°C - 15°C = 485°
- 485 * 200J = 97kJ
- 10MW = 10,000kW = 10,000kJ/s
- 10,000kJ/s divided by 97kJ = 103 units/s

Current Output per second (fluid)
- Actual input fluid temperature: 165°C
- 500°C - 165°C = 335°
- 335 * 200J = 67kJ
- 10MW = 10,000kW = 10,000kJ/s
- 10,000kJ/s divided by 67kJ/unit = 149 units/s

Why not adjust the Max. consumption until it shows a proper 103 out of 103/s?

• We can try, but it will adjust both values to give the same ratio as 149 out of 103/s --> 103 out of 71.1/s
• It does this because it assumes the input fluid should be 15°C, deriving the maximum Output rate to be 71.1/s, and the current Output rate to be 103/s

Ae you sure this isn't a cheat entity?

• Yes, the energy consumption and fluid processing rate - while weird to look at - is above board.