Boiler House becomes available after the Heat Sink and, in fact, is a perfect counterpart for it. While Boiler House in itself is fairly fragile and will explode if it comes into a direct contact with heat exceeing 2000, it has an ability to extract a bulk amount of heat from Heat Sink or Generator and sell it at once.
So long as the object in question continues to have more then bulk value. Boiler House will continue selling that much each tick. However, unlike Offices, Boiler House is incapable of selling less then it`s bulk value. If the heat demand is not met, no sale will happen that tick.