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Hot Tub Heater Repair

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Replacing a Hot Tub Heater - Spa Heater Troubleshooting

Hot tub spa heater for sale at Hot Tub OutpostSpa heaters usually last a long time.  Some things like improper water chemistry can shorten the life of heater elements as well as seals, orings and other hot tub components. 

That is one of the reasons it is important to maintain pH between 7.2-7.6 and to check the water with test strips or a test kit regularly.

The hot tub heater is a metal cylinder connected to the hot tub plumbing and spa pack which contains a flow-through heater element inside and a metal sheath or manifold on the outside. 

Other heater types include trombone style heaters and even external gas powered heaters. 

Horse Sense
Warning: Working on your own appliances, cars, covered wagons and hot tubs as well as anything else electrical or mechanical carries with it severe risk of injury or property damage. These tips and suggested procedures are free and for informational purposes only. Proceed at your own risk. It is best to use the services of an electrician or tech. Hot Tub Outpost is not liable for any damage or injury that may result.

This article is about the Balboa flow-through electrical spa heater. Before making any heater repairs or testing the heater or electrical components, make sure the POWER IS TURNED OFF at the main breaker.

hto heaters spasTwo posts with mounting nuts which are encased in epoxy on the top of the heater tube are connected to the circuit board in order to power the heater.  The spa electronics give the circuit board a signal when it can apply power to the heater terminals.  

Hot tub heaters also have either internal or external sensors which monitor the water temperature and possible overheat conditions.  Older style spas may have an external pressure switch that is sometimes mounted to the heater tube. Newer style heaters such as the Balboa M7 type have these two sensors mounted inside the heater, eliminating the need for an external pressure switch.

Heater failure can cause the GFCI or breaker to trip.  A service technician will disconnect the heater terminals (with the spa powered down and the circuit breaker off) to see if a tripping GFCi may be caused by a short circuit in the heater.

Caution: These two heater terminals have full voltage and can cause shock, so it is recommended to only allow qualified persons to work on a spa and also that the power is off and the breakers also turned off.

Hot Tub Heater Brand List - Hot Tub Outpost Has 'Em All

  • Balboa
  • Brett Aqualine
  • Cal Spas
  • Gecko
  • Hayward
  • Hydro Quip
  • Jacuzzi
  • Sundance
  • Therm Products
  • OEM-Generic and more...

 See all of our hot tub heaters.

Replace your hot tub heater with the same kilowatt rating / voltage. Although we also sell the individual heater elements, it is recommended to change the entire heater manifold when in doubt, or if the heater is more than a few years old as changing out heater elements can cause issues at the epoxy seal, or it can come in contact with the metal sheath creating a short. Changing out the entire heater tube including the heater element is an easier process and eliminates the guesswork of troubleshooting a heater element that visually looks ok. 

When switching out the heater manifold, be sure to remember the o-rings/gaskets that go on both sides of the heater. These 2 gaskets (one on each side) help avoid leaks at the heater union that connects to your spa plumbing.

Heater Repair Tips 
If you are removing the heater from the plumbing, do not remove the screws that may be on the heater union.  It is also a good idea to replace the heater gaskets when closing the heater tube back up.  If the heater union is leaking, tighten the union to see if leak stops, but do not over-tighten to avoid cracking the union.  Also inside each side of the heater union (plumbing part that connects the heater tube to the hot tub plumbing), there is a heater gasket.  This may also need to be replaced if the union is leaking.

Spa electrical and heaters should only be worked on by qualified persons as working on any appliance can be very dangerous and lead to electrical shock or other injuries.  This article provided for information purposes only and is not intended to be a comprehensive how to guide.  Call a qualified tech if you need assistance in repairing your spa. Qualified techs may use this information as a primer on some things that can go wrong with hot tub heaters.

The heater is often coupled with the spa pack such as many of the newer Balboa heaters and spa packs. When accessing the heater, the power pack door is opened by removing the top 2 screws on newer Balboa packs.

Tripping GFCI

One of the number one causes of a tripping GFCI or hot tub heater failure is that a drop of water may find its way onto the heater post between the insulator and the post causing a short circuit.  If that happens, the GFCI trips for safety reasons.  A test to see if the heater is causing the GFCI to trip is to remove power from the heater to isolate the problem.  Note that there are many causes of a GFCI tripping including a problem with the spa pump, ozonator, blower or other spa component.

If removing the heater strap from the heater, hold the part with a wrench to avoid breaking the heater post.  Newer Balboa systems such as the BP2000 series have a dedicated heater connector that can be unplugged instead of opening the heater strap connection. 

To isolate the heater from the pack, the power to the heater is removed.  If the breaker resets, then the problem is with the heater and it may need to be replaced. Some may decide to try to replace just the heater element, but the epoxy that holds the heater post in place as well as the actual placement of the heater element makes this an exercise not recommended. It is best to replace the entire heater.

Multimeter measures hot tub heaterHeater Testing

Resistance Tests - Heater Continuity
There are several multimeter readings that can be taken from the heater posts to determine what a problem might be with a spa heater.

Heater Test 1):  Place the 2 measuring probes of the multimeter on each of the 2 heater posts.  The resistance reading for acceptable heater ohm ranges are:

  • 1kw heater @ 120 volts          9.4-11.5 ohms
  • 4kw heater @ 240 volts          12.96 - 15.84 ohms
  • 5.5kw heater @ 240 volts       12.96 - 15.84 ohms

If the multimeter shows a 1 or OL then there is no continuity and the heater will need to be replaced. Find a new spa heater at Hot Tub Outpost.

Heater Test 2):  Place one multimeter probe on the left heater post and the other on the metal heater tube sheath/manifold. The meter should read 1 or OL to show there is no conductivity between the outer sheath and the heater terminal.
Repeat this test for the right heater post and make sure there is no conductivity between the right heater post and the metal heater tube.

When the tests are complete, connect the heater again.

Insulated heater clamp test for testing a hot tub heater.Voltage Tests

Before setting up the voltage test be sure the POWER IS OFF AT THE BREAKER. 
Use insulated clamps to clamp onto each of the two heater posts.  Be certain that each clamp is not touching the other one.

Set the multimeter to read AC voltage.

Once the heater probes are attached correctly and not touching each other or anything other than the heater post, turn breaker on to get power to the control panel and spa.  With the hot tub powered up, be sure the panel is in standard mode and raise the temperature so that the spa calls for heat.  This should normally apply power to the heater and there should now be the full operating voltage across the heater. This may be about 120v, 230v or 240v depending on how the spa is hooked up.

After the voltage reading is taken, power down the circuit breaker and spa again and then remove the test clamps.

Amperage Tests

An ammeter is required to test the heater for amperage.  The ammeter clamp is placed around one of the heater supply wires.

According to Balboa Instruments (aka. Balboa Water Group), the acceptable heater amperage draw ranges are:

  • 1kw heater @ 120 volts          7.58A - 9.26A  (120v amp draw)
  • 4kw heater @ 240 volts          7.58A - 9.26A  (120v amp draw)   or    15.15A - 18.52A (240 volt amp draw)
  • 5.5kw heater @ 240 volts       10.42A - 12.74A (120v amp draw)   or    20.83A - 25.48A (240 volt amp draw)

 Ammeter Test Hot Tub Amperage

Other Spa Power Issues
Another issue is the 0.3 amp system fuse on the circuit board which could render the entire spa in a non-operating state.  Nothing will work including the topside control panel if the 0.3 amp fuse has blown.  Whenever work is being done on the power pack, be sure the electricity is off/disconnected and breakers are off for the safety of the techician or anyone else working on the spa.

For assistance on getting a new replacement heater or other spa parts, contact Hot Tub Outpost USA.

See our spa heater section for the current line of inline hot tub heaters.

Here is a video for electricians to see how the flow through heater is replaced and also shows adding a pressure switch.

See the complete replacement spa heaters, heater elements, pressure switches and heater parts.

Spa heaters at Hot Tub Outpost

We also offer flow through heater elements and pressure switches.

spa heater elements hottuboutpost