Cant activate mod on save game.
when i activate it there is nothing to see from the Gas-fired boiler.

Sometimes, when you add the mod to an existing game, and you've already researched the technology, the game will not realize this and not automatically enable the recipe. Sometimes it does enable it. Not much I can do about that besides rewrite the system in a control script in every one of my mods to make sure the game is properly trolling the tech tree every time someone adds a new mod, which introduces new points of failure in every one of my mods, and so is something I feel instead needs to be handled in the core game. At any rate, this can be fixed by running the command /c game.player.force.reset_technology_effects(). You can use the admin command mod to run the command if you're concerned about disabling achievements.

thanks
it worked

Glad to hear it. Thanks for bringing it up. Your comment will probably help others who come by, too.

Sometimes, when you add the mod to an existing game, and you've already researched the technology, the game will not realize this and not automatically enable the recipe. Sometimes it does enable it. Not much I can do about that besides rewrite the system in a control script in every one of my mods to make sure the game is properly trolling the tech tree every time someone adds a new mod, which introduces new points of failure in every one of my mods, and so is something I feel instead needs to be handled in the core game.

How about a migration script? You know what technologies your mod(s) depend on, what unlocks what, so you could soft-reset these technologies with something like this:

local technologies = {"tech_1", "tech_2"}

for _, force in pairs(game.forces) do
    for _, tech in ipairs(technologies) do
        if force.technologies[tech] ~= nil and force.technologies[tech].researched then
            force.technologies[tech].researched = false
            force.technologies[tech].researched = true
        end
    end
end

Hey Pi-C, thanks for the suggestion and I do realize that. As a devops engineer I just have a sort of philosophical issue with installing code that is identical across all mods, or adding more copies of the same code each time I make some change. When that happens it tells me a systematic approach is needed, and I've been meaning to open a feature request regarding this issue, but I just moved 500km, so been a bit busy.