Just a follow-up. Mom didn't like the look of the walk-in tub. It also has a distinct disadvantage. You have to be in the tub to run the water because the level of sitting is so high. You also have to wait until the water drains out of the tub to open the door before you can get out. They also have some that can be used as a shower in addition to tub. This was an advantage because the water would continually drain out while showering, but could sit down if needed to.

As my mother was aging, I was looking out for some good options in the area of walk-in tubs, as due to her increasing age she is getting less agile. But personally speaking, I was never much in favor for installing walk-in tubs, as I felt those are really waste of money and ultimately occupies your bathroom space in no good way.Walk-in bathtubs usually have a watertight door on one side that allows someone with limited mobility to step into the tub without having to climb over the side of a standard tub. But one my friend recently installed these walk-in tubs from Safeguard Tubs, she highly recommended that to me. Though having no alternatives I went by her suggestion and installed & I must say it was worth every single penny. The best part was it had non greasy floor and support bars which acted very helpful to my mother and left me tension free. Definitely a good deal to crack !

Do you have a specific tub in mind? We have a Bain ultra air tub and I couldn't imagine showering in it every day. The acrylic bottom along with the added height of the side.... to me it seems like an accident waiting to happen. I guess it would depend on the height of the tub you had in mind. In regards to the automatic air purge, it only happens after the air cycles off. You wouldn't be turning the motor on when you shower so the automatic thing wouldn't happen.

For a jetted tub used as a shower, it has to have an integral tile flange. That allows the wall cladding to overhang and any water that hits the wall to not go behind your walls. There aren't that many in that size that are inexpensive. It will need a specialized drain, and, if you want to spend any time in the tub, a supplemental heater so the water doesn't cool off so fast. Since it's a tub/shower, the wall cladding will need to be redone to be waterproof into the tub. It's possible, if the build is recent, and it was done with the proper vapor barrier behind it, that only one row of the tile would need to be pulled in order to replace the tub. But, I wouldn't count on that. I'd count on having to replace all of the wall cladding in the alcove. That can be as cheap as a plastic surround for around $100 or cheap tile with the proper vapor barrier for probably $150 or so. The first is the easiest and the least chance of leaking. The second will read as more upscale, but you have to be sure your contractor understands about the vapor barrier and correct materials to use to tile this (NOT mastic.) And since you have that torn out, it would be foolish to try to keep your current control valves for the bath unless they are also very new. New safety standards are in place for anti scald mechanisms. So, you will need a new shower/bath faucet and valve. Then you will need the electrical line run from the panel to the location for the whirlpool pump and supplemental heater. That location is usually opposite the drain side of the tub. You will need to be able to site an access panel that is removable to be able to get to the electrical innards here. That can be from an adjacent room, or from a hidden panel on the tub itself. All in all, you might be able to get all of the needed materials for 2-3K if you shop the box stores carefully and find some bargains. The danger to that is that if you are inexperienced, you don't know if you're buying quality or crap. They sell both. And that's one reason that it would be simpler to let the pro pick the products after you tell him the features that you want. Then you've got to pay the contractor labor to install all of that. The electrician's price will depend on how difficult it will be to access the panel and run the wire to the location. For that, it's a really good thing you are on a crawlspace! That makes it cheaper for both the electrician and the plumber. On the whole, I'd expect your project to cost between 5-7K, depending on location, and if you have no DIY skills to bring to the table and have to hire professionals for the whole job. And be sure that you hire someone that is licensed and insured to be in your home, and will pull the proper permits to get the job inspected with your code office. Some handyman guy isn't licensed to do electrical of that nature, and while he might be able to do the demo and get the tub in place and glue on the plastic surround, it's unlikely that he'll have the right insurance to deal with a large job like that, and thus probably wont' want to pull permits and be inspected. They are usually limited to smaller jobs like simple fixture replacements like a faucet or light. Which this isn't. Just remember, you are doing a project that combines electricity and water. You really have to know what you're doing here! A small General Contractor should be able to do the complete job, and also carry the needed papers. And he should have no problem with the code guys coming in to inspect his work either. If he does, then he's not the right person for the job.