We have a flexible 1 1/2" line on our tub. Can the heater be installed on a flexible line?

If you had a tank-type heater, and installed tankless, then you cannot use the same gas line pipe. You must have 1" gas line running to within 10' of tankless unit, and then 3/4" to tankless... and you cannot use flexible gas line.
You can use same hot and cold water pipes, but install service valves so you can delime the heat exchanger each year.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Gene


Water Heater Timers Save Money

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Bath tub heaters will only maintain the water temperature in the bath. They will only heat the water approximately 1-2 degrees an hour.
Whatever water temperature you start with is what you will be able to maintain.
There is a red indicator light on the front of each heater indicating whether or not there is power to the unit when the tub is full of water and the water pump is turned on.
If there is a red light on then it has power to it and is working.
This heater will never feel warm to the touch.
There are three different styles of Bath Heaters available.

• Tee Heater - installs on the discharge fitting on the pump
• In-line Pressure - installs anywhere in the plumbing line before any jet.
• In-line Vacuum Heater - installs before the suction of the pump

If the heater you purchased is installed in the wrong place it will not operate.

Rod
US Parts Center

It is always possible to add a heater to any jetted bathtub at any time.
What you need to find out that is if the tub is plumbed to each jet with rigid PVC pipe or flexible PVC pipe.
If it is plumbed in flex pipe then the Tee heater will be easier to install however if it is plumbed in rigid PVC then I would suggest a inline pressure heater that you will install in the water line any place after the discharge of the pump.
Here is a link to a installation instructions so you can see how all heaters are installed.
US Parts Center

Water heater can be added to any incoming water line, either on hot or cold.
http://waterheatertimer.org/How-to-install-under-counter-water-heater.html
Under-counter water heater located near tub will supply hot water just like ordinary household water heater. But it will not reheat water that circulates inside the spa tub.
Otherwise, a spa heater is made with electric element that can work with 120V or 240V. Water from tub circulates through tank that holds element. Element must be fully immersed in water.
To retrofit spa tub with this heater would require cutting water line near pump, running both ends of water line into tank with element.
Then of course you would need to retrofit adjustable thermostat to control when element is on. And integrate element operation into air control switch at tub that can override thermostat so element is not heating when tub is not in use.
Unless there is a pre-packaged kit to retrofit heater, I think adding heater would be difficult.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

In line heaters will not HEAT the water, they will only maintain the temperature inside the tub within a few degrees. You should not try to install the heater yourself, it would be best to have a plumber come over and give you a quote on how much it would be to install it. A plumber can look at the tub, see if there is a place that the heater can be CUT IN to the pipes, and install it. You likely won't get it to work. The inline heaters are required to be put on a GFCI circuit because they are powered in a wet environment. Unless your tub is not hardwired in to the house, and you actually have a GFCI circuit under the tub. But like I said, these do not heat the tub, they only maintain. And the life of these is not very long if you use soaps and shampoos in the tub while the heater is on. It won't take any time at all for the oils to build up on the elements, rendering it useless.

Yes, you will need a regulator at the tank that can handle the maximum Btu Output of the heater. In addition to that, you also need enough 1/2" Flexible Copper Gas piping to run from the tank valve to the heater. In the line passes through a brick, cinder block or concrete wall, the gas line MUST be sleeved with either Black Iron Pipe or Rigid PVC Pipe. You'll also need assorted flair nuts and connectors.. As well as , a Inline Gas Shut Off Valve within a minimum of 2' from the heater. You will alos need a pipe bender for flexible copper pipe.

Having a friend who has a lot of knowledge and tools for installing gas appliances (running lines, making leak-less connections, etc) really helps.

Sure is. You simply need to purchase a to 3/4" to 1/2" Male to female reducer. You didn't mention if your current gas piping is flexible copper, rigid black iron pipe or flexible stainless steel. In any event, get the one that matches your current gas piping. If all of your other gas appliances require an individual regulator, then you'll need one for the tankless water heater. If in doubt, contact your propane provider.

Hope this helped answer your question and provide a solution.

The bath heater you have is not designed to HEAT water - they only Maintain what you start with.
You need to start the bathtub with the hot water you want. It will only heat about 1-2 degrees an hour.

First thing to do is wrap rag or towel around spraying joint to localize water.
Next, turn off power to water heater.
If gas, rotate knob to pilot so pilot light stays lit but burner does not come on
If electric, turn off circuit breaker.
Close cold-water shut off valve above tank.
Open tub valve to release pressure on water heater.

Wait for water to cool before working on water heater to avoid high pressure scalding water.
When finished, make sure tank is full of water and water comes out of tub valve before turning on power.

Water heater should not have plastic couplings.
I can't see your problem exactly, but water heaters have 3/4" nipples coming out of top.
Easiest solution is use flexible connectors from Lowes or Home depot.



Flexible connectors are 24" or 30" long and have 3/4" nut on each end, so disassemble existing pipes using pipe wrench.
Lowes and Home depot can help you select appropriate pipe >> take several phone-photos of your pipes to home center so they can see your problem precisely.
Attach 3/4" male adapter on end of pipe.
Attach flexible connectors between pipe and water heater nipple.
Cold water line has shut off ... make sure this attached to nipple marked cold.
Make sure hot pipe is attached to nipple marked hot.
Use teflon tape on threads.

Add a comment if you need more help.

I had same problem... fixed by turning hot water tank up to 145 degrees...but PLEASE do not do this if you have young children..that is hot and will burn!.. but does work(did this 8 years ago!)