Having installed a tankless/on-demand water heater myself, I highly recommend them, especially when you have large tubs to fill.
The walk in tub you mentioned can easily hold 45-60 gallons of water which typically requires a larger 75 gallon tank or two smaller 40 or 50 gallon tanks tied together which is more typical.
- As you may be aware, the benefit of the on-demand water heater is that it only heats the water when you need it, reducing the energy needed to keep a tank full of water hot and ready to use.
- Plus you can easily dial in the exact temperature you like, so there is additional energy savings by not mixing cold water at the shower or tub to get the perfect temperature at the faucet.
Now tankless systems are more expensive to have installed than a standard atmospheric water heater and the payback is long in terms of the energy savings from the more efficient on-demand water heater.
However one thing that makes it worth the added cost is that they are sealed combustion units. Meaning that the combustion process is completely enclosed in the unit, greatly reducing the possibility of carbon monoxide from getting into the home.
Look at your water usage and habits to determine the size of water heater you will need.
- Do you have two showers going while doing laundry or washing your dishes?
- You need to take this into consideration when sizing your unit.
- However the size of your existing gas and water line may limit you to a smaller size which is enough to run two showers simultaneously.
For more information:
Read "What are the pros and cons of a tankless water heater? We are considering replacing our gas hot water tank." a Q&A answered by Danny Kelly.