How long do I have to wait for the water to get up to temperature?

This varies depending on the size of the hot tub, the air temperature and how good the firewood is that you use. Generally they take between 2.5 and 3.5 hours to heat up.

Dry, seasoned hardwood or heat logs make the biggest difference to heating time. If you cover the tub after an evening soak, the well-insulated water will often still be warm enough to use the following morning.