Is an in-line heater essential for a whirlpool?

Is an in-line heater essential for a whirlpool? How does it compare to just adding more hot water while letting excess water drain?

If there a clear cost saving but having an in-line heater vs. adding more hot water?

Thanks

You'll probably be more comfortable with the heater. Depends on how long you sit in the tub and soak. Energy-wise, depends on how your utility rates are as electrical where I live is more expensive than gas, but if you have an electric WH, that's a tossup. Seems a shame to waste water just to get things warmer, though. Water and sewer rates are rising most places.

IT depends on the TUB. Some are very well insulated so there is a minimal heat loss, but others are just the shell and they will lose heat rapidly, so they would need the heater.

Thanks for the feedback guys...

We are looking at the "Archer" model from Kohler. Not sure how well insulated it is... so for now we are getting the model with the in-line heater.

If you like to take long hot baths, then the heater is a no-brainer. But if you just like to soak for a 20 mins or so, then imo, having the heater is a waste of money and just another future leak/service issue with the tub.