Well mech flamers are not standard flamethrowers. They are channeling high energy plasma from the fusion reactors.
If you want to bring realism into it, then the amount of plasma that could be diverted from a fusion reactor in order to power the flamer is not going to be a lot...grams perhaps.The temperature of the plasma may be high, but with so little material involved, the amount of energy in the plasma stream is going to be negligible. It's also something that can be matched by a vehicle flamer. You could argue that they could add additional reaction mass to the plasma stream, but then we're talking about an ammo based weapon.
As for it only being a minor complication....true, but I feel there are a LOT of "minor" complications and they all add up. And there are other rules which add complications to the game without, I feel, much in the way to recommend them. Flamethrowers are too heavy, and if it were me I'd simply delete the Fusion Flamer and reduce the Vehicle flamer mass by half and simply state that it is still heavy beause it incorporates four flamer systems into one. Or something like that. Mech armour should be easily able to handle the heat from a flamer, but having the units heat dissipiation system operate at reduced efficiency is a decent debuff to offer. I might be even tempted to suggest increasing the heat debuff a bit. Plus, there is the use against infantry, the ability to set fires, and so on. Flamers have their use but whether or not they are "worth taking" or "underpowered" simply makes them mission specific.
But not going to go into detail here.
Funny enough that actually does not change my question.
True, but I was answering the original post.
My question is based around how all the other weapons that raise heat have special rules on how they interact with all sorts of units that are not battlemechs and aerospace. A single inferno missile raises heat the same as a flamer set to heat (which you just said is the mode you believe that should only work) but yet inferno missiles have special effects on say a tank or battlearmor but the flamer does not. Why is that?
Because the games designers want each system to be "useful". Personally, I think this is a matter of complicating the game with no great benefit. Flamers, inferno, et al should all have a consistent set of rules based on their operations.....which should be covering a target with flammable gel and igniting it. Another reason why the Fusion flamer isn't a great idea. These weapons should deliver heat to the target - not damage. So, against Mechs they impede the cooling system. Against infantry, they deliver burning damage. Against vehicles and ASFs...which don't track heat and have mech scale armour...the question arises should the weapon do anything at all? And the answer in this case would probably be - if there were to be a "realistic" effect, it would depend on the engine, with an ICE having some potential vulnerabilities if there were ventilation (etc) requirements, but its unlikely.
So - IMO, there's no issue with flamers being inefficient, and no real need for them to deal damage to Mechs or other armoured units. BUT they should be amongst the best weapons for anti infantry and anti building work, good enough to justify their inclusion on specialised units.
But again...all this is my opinion. The original post asked if I used Enhanced Flamers, and the answer is "no" to the point where I discourage flamer caused damage entirely.