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

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No heat with Rapid Heat U395000 Jacuzzi jetted tub

Just installed a new heater and the light is on, tub is full, no leaking, hit the reset and I'm not getting any heat. What's next?

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When you changed the heater did you make sure you also changed out the temp sensor cause most of the time calciun builds up an is the reason for both the heater an sensor to fail calcium is ok at temps above 93.6 degrees but as soon as the temp drops below this point it will come out of solution an start to harden on the element an sensor.Always make sure to that you are getting power from the spa pack to the heater check for voltage at the main leads on the heater just because it says its on does not always mean you are getting power to the heater.Always remember with spas the problem lies where the power dies.sometimes it can even be your main top side controls they can go bad an indicate the heat is on but will not relay that to the heater.make sure you got the correct kilowatt heater also an that you have the correct one in terms of 240v or 110v also from the thousands of heaters i have replaced in spas over the years i always check to see if i am getting the correct omhs reading before i install them should be around 8-10 for a 110 an 12-13 for a 240

Posted on Mar 27, 2010

  • If you still have your old heater do a ohms reading if you are getting the corect reading it might of not be the heater that went bad both the t-stat sensor and high limit can cause no heat.But in most cases if the heater is good an still no heat it a power issue if the reset has been reset also if not heating from the low speed from your pump an is using a circ pump make sure that its still good cause u can hit the reset an it will start to heat but the tripp again a minute later. But first start at the powr going into the spa at the heater term on the circuit board then move on from there u might get power going into the spa but the on n off relay on the board could of went so then look for power at the heater if u have power at the board but no power at the heater then most likely its the board that went bad if no power at the board make sure your 30amp breaker is still good cause alot of 30amp gfci breaker especialy seimens can burn up an then it will not send the power from the house into the shut off box to the spa.The other cause for no power at the board could be the result of a bad main topside controls they tend to use cheap ribbon cable that go bad you will still get a heat indicator light come on but the topside controls will not send the singal to the board to turn on the heat even the mainn controls have a little circuit board that relays imfo to the main circuit board also mice love to eat the ribbon cables an one tiny tear can cause this to happen good luck


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

Posted on Feb 08, 2010


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Look on the heater for a label. If your heater is installed on the discharge side of the pump it should say "pressure heater" on it. If it is installed in front of the pump it should say "Vacuum Heater" on it.
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