M291 S5 J1 F60 L0 H100 R"Set Hepa Fan Speed in %" P"Recommended values: 50–80%."
var speed = floor(255 * input / 100)

set global.hepafan = var.speed

echo >"0:/user/hepafan.g" "if exists(global.hepafan)"
echo >>"0:/user/hepafan.g" "  set global.hepafan = "^{var.speed}
echo >>"0:/user/hepafan.g" "else"
echo >>"0:/user/hepafan.g" "  global hepafan = "^{var.speed}

M106 P7 H3 T50 X{global.hepafan}         ; Configure thermostatic control

echo "HEPA fan speed set to " ^ input ^ "%"