Question about Jacuzzi RapidHeat In-Line Heater U395000 [ Bathtubs and Whirlpools,

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Rapid Heat Bath Heater - indicator light on but not heating water

We've had our tub with inline rapid heater for 7 years. The last 2 times we used the tub the water won't heat. The thermostat on the unit is turned up, the indicator light is on, and the high limit reset isn't tripped. Any advice?

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  • David Shaub May 11, 2010

    The thermocouple thet tells the unit to heat is probably burned out.They're not hard to replace nor expensive. Contect your local dealer for the exact part for your unit.


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Bathtub heaters will not produce the heat out a the jets like you would feel coming out of a return jet in a swimming pool.
Bathtub heaters will ONLY maintain whatever temperature water you put in there. they only heat 1-2 degrees an hour. that is for a 1500 watt heater. Many heaters today are only 650 watt or perhaps 700 watt.

Posted on Feb 24, 2009

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New replacement in-line heater (C3B54P0-3002AU0) inop.

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.

US Parts Center

Dec 04, 2013 | Maax Calla 6042 Bathtub - 101058-000

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In-Line heater does not operate

an inline heater does not heat the water it only maintains the water temperature that is in the bath. try filling the bath with the required water temperature and see if the heater maintains that temperature. good luck

Dec 04, 2013 | Maax Bathtubs & Whirlpools

1 Answer

Can Jacuzzi Rapid Heat inline heater be installed upside down?

You do not want to install any heater upside down because if any debris gets inside the heater pressure switch while it is running it will NOT shut off once the pump shuts off.

US Parts Center

Feb 17, 2013 | Jacuzzi RapidHeat In-Line Heater U395000 [...

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Jacizzi tub and water is not hot enough

When filling the tub if there is not enough hot water to fill the tub you will probably need a bigger water heater.
You can add a Bath Heater to your tub if the water is cooling down too quickly while you are using it however, a Bath Heater will NOT heat the water. They will only maintain the water temperature you start with.

US Parts Center

Jan 08, 2013 | Bathtubs & Whirlpools

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Why does it take 12 hours for my tub to heat up. The heater runs for about 3 hours then turns off. I turn off the power, wait 20 minutes and do it again over and over. It only gets about 70 degrees. One...

This is a bathtub heater. it is only 1500 watts. they are not meant to heat the water in a bathtub. They are considered a maintenance heater ONLY.
This style heater will maintain whatever temperature you put in the bathtub. It will only produce about 2 degrees of heater per hour.
solution: start with the water temperature where you want it to be when bathing and this heater will keep it that temperature while the pump is running and the tub is full of water.

Jan 24, 2011 | Jacuzzi RapidHeat In-Line Heater U395000 [...

1 Answer

The light will not come on after starting jets and the reset button has been reset. The water is hot in the tub. brand new unit

i have the same problem, checked ohm's there good at 15, why won't the rapid heat light come on letting me know t's working?

Jan 16, 2011 | Jacuzzi RapidHeat In-Line Heater U395000 [...

1 Answer

I have a new Jacuzzi tub with a Rapid In-Line Heater. When I fill the tub the water the initial temp is 67 degrees. The heater only increases the temp to 71 degrees. What is wrong with the heater ,if...

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.

Jan 08, 2011 | Jacuzzi RapidHeat In-Line Heater U395000 [...

2 Answers

No heat with Rapid Heat U395000 Jacuzzi jetted tub

can be thermal overloadswich somewhere. it switches of when there is no or not enough water in heatingpipe

Feb 07, 2010 | Jacuzzi RapidHeat In-Line Heater U395000 [...

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Need to heat water up more

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!)

Mar 15, 2009 | Jacuzzi RapidHeat In-Line Heater U395000 [...

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