Will this unit heat my spa? How hot will it make my spa?

We will need specific details regarding your spa, but in general the HE 150 is more than enough to typically heat your spa. You should see about a degree every three minutes while heating and it will get it to a 104°. It will operate like this as long as it is above about 50° ambient outside. If you want to run it while it is colder than that outside, you would need the heat cool option and it may take a little longer than the 1° every three minutes. Please give us a call, and we can further assist you to get your the unit you need, thanks!