I do not like the rules for fire in Dark Heresy. Firstly, they require way too many die rolls and slow down combat. Secondly, they render characters entirely helpless if they can't pass a Willpower check. And finally, a decently-armored character actually has very little chance to die from fire damage itself -- instead, he will slowly take Fatigue until he eventually collapses and dies over a minute later. I would like fire to be very dangerous if left unchecked but allow people a decent chance to contain it, and I feel that the current fire rules don't cut it.

I've been considering adapting the burning rules from the first version of the DH2 Beta. In those rules, all weapons that set people on fire had a variable strength -- a weapon with Flame (X) inflicted the Burning (X) condition on anyone it hit. Hand flamers inflicted Burning (3), regular flamers Burning (6) and heavy flamers Burning (12), and many Pyromancy powers caused Burning of some sort as well. Burning worked as follows:

1. At the start of your turn, you take a hit of X energy damage to a randomly determined location.
2. The value of X is then doubled.
3. If you receive another instance of Burning (X), you add the two values of Burning together.
4. You or an adjacent ally could spend an action to try and put out the flames. The burning character drops prone and makes a +20 Agility check -- if successful, the flames are extinguished.

How do you like this option? I'm considering also inflicting a level of Fatigue for each round a character remains on fire -- would that be a little too brutal, or just brutal enough?

Has anyone house-ruled Flame weapons to function differently? If so, are you happy with the changes?

Fatigue seems too brutal to me. The rest seems good to me.

Doesn't being on fire cut straight through armor because you are literally cooking in your armor?

My group got set on fire and yes it slows down combat a bunch when seal wounds is in the equation, what I did though was when combat ended I gave a larger bonus to put out the two people on fire depending on how much gear they wanted to lose, they lost their armor and a good chunk of ammo but they lived.

Fire (being on fire, not the initial attack) ignores armor entirely except from the Machine Trait.