cs1006

bought a used for spare spa pack just in case , i am bench testing briefly when i plug it in it fires right u and is very quiet with a vaccuum pump i can activate high speed , so back on low speed i noticed the red heating lite is not on , when had my existing spa pack impeller wheel replaced i plugged it in and the heat lite came on instantly , im testing these packs on my workbench , i dont know if different brands react different ways, if they need to have water in the elements or pressure etc but if i need my backup one day i just wanna make sure its gonna be a plug and play system