New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  val: '',
  actions: {
    update(val) {
      val = +val; //cast to int;
      if(val) {
        Ember.set(this, 'val', val);
      }
    },
    reset() {
      // how can I enfore the <input> to update, even if its 0?
      Ember.set(this, 'val', '');
    }
  }
});

templates.application.hbs

<input value={{val}} oninput={{action 'update' value='target.value'}} />

<button onclick={{action 'reset'}}>reset</button>

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.7.0",
    "ember-data": "2.7.0",
    "ember-template-compiler": "2.7.0"
  },
  "addons": {}
}