Hot Tub & Spa Heater
Repair, Help & Troubleshooting

WARNING

The information contained here is but the basics. If you feel unsure or uncomfortable in these types of repairs please contact a qualified spa technician. Use any of the information contained herein AT YOUR OWN RISK. These instructions are primarily intended for use by qualified personnel specifically trained and experienced in the installation and repair of spas, electrical equipment and related system components. Installation and service personnel may be required by some states to be licensed. Persons not qualified should not attempt to install this equipment nor attempt repairs according to these instructions. Please remember that water and electricity DO NOT MIX. If you are not capable of performing a repair yourself, please contact a local spa professional or a licensed electrician in your area. This information is presented for informational purposes only, and we will not be held liable for any injuries that may result from the troubleshooting or installation of any electrical components in your hot tub or spa.


While the heating system of a spa may seem complicated, it's really quite simple. When conditions are right, electricity travels through some switches and relays, and is applied to the heating element causing it to get hot and the heat transfers to the water (for gas heater, see the chart below). Besides some basic hand tools, a volt/ohm meter and amp meter are necessary for proper testing. Without these test meters, any repairs made to the spa will basically be trial and error and will usually result in parts replaced that weren't actually bad (not that we don't appreciate the business:-). If you're not sure how to use these meters, do not continue with any diagnostic or repair attempts. Call a qualified spa technician! If you need some instruction on how to test for the proper voltage, please see here.

If the spa is not heating at all the first thing to determine is that the pump is moving water through the system (the heater wont operate if there's not sufficient water being pumped). If the pump is working correctly, the next step is a few electrical tests to determine the problem.


"NO HEAT AT ALL, NOT ONE BIT, NOTHING !"

This is very different from "it's getting a little bit warm". It could have the same cause, but a heating element is like a light bulb, it either works or it doesn't. If there's absolutely no heat the first thing to test is the heating element. IS IT GETTING ELECTRICITY? (Hint, if you have a 240v heater, you must test for 240 volts directly at the two terminals of the heater. Testing from one terminal to ground will give a proper reading even if the element is bad).

The element IS getting electricity.

If the element is getting electricity the next test is an amp test. If you don't know how to perform an amp test "call a qualified spa technician. Generally, a 120v heater should pull 12.5 amps and a 240 volt heater should pull 25 amps. If you're getting proper amperage draw, move on to "it's getting a little bit warm", below. If you're not getting any amperage draw, you have a bad heater element.

Now the hard part, identifying the replacement element you need. Unfortunately (or fortunately) most all spa manufacturers acquire ALL their parts from elsewhere, assemble them into a spa and slap their name on it. Rarely is the brand of spa relevant in determining a specific replacement part needed. This means that rarely can parts be identified from the brand of the spa. With heaters and heating elements especially, about the only way to identify them is visually. Once you determine your heating element is the culprit and it's been removed from the spa, you can visually match it up to (hopefully) a comparable replacement.

A perfect match is not always possible, and some differences are just fine. Some of the acceptable differences are;

  • Difference in physical length. A shorter element is perfectly ok, as long as the other specifications match up. A longer element may not fit the existing housing.
  • Slight difference in kilowatt rating. A difference in "kw" rating of 1/2kw is perfectly acceptable. Frequently, a 6kw element will be replaced with a 5.5kw element.

The two most important things are;

  • The 'flange', or how the element attaches to the heater housing must be the same (some unusual or obsolete elements may require a different element along with an adapter). If your heater element is threaded, the picture below should give some guidance on sizing and measuring for replacements.

 

  • The voltage rating must be the same. An element rated for 120v only, cannot be used in place of a 240v element, however, an element rated for 240v can generally be use in place of a 120v element (sorry no, you wont get any more heat this way).

The element IS NOT getting electricity.

Ok, so the element is not getting any power. Using the light bulb analogy, "the light switch is broken". Using the volt meter, start at the heating element and follow the wiring back until you find the switch or relay that isn't allowing electricity to pass through. If power for the element is fed through a relay and the relay isn't closing, it then must be determined why, or what switch is preventing it. The next step is to determine if the switch is truly bad, or if it's just doing it's job (a high limit switch may be cutting off due to some other problem that's causing the water at it's sensing point to over heat).

Some of the many possibilities for a good switch to appear broken are (and the apparent culprit);

  • Low water flow (hi-limit, pressure switch or thermostat)
  • A dirty filter (hi-limit, pressure switch or thermostat)
  • A clogged tube feeding a pressure switch (pressure switch)
  • Magnetic door interlock misaligned (door interlock)
  • Heating element shorting out into the water (GFCI tripping)

If all of this doesn't seem to make sense, you feel you need a lot more information or you don't feel comfortable in attempting this type of diagnosis or repair, "call a qualified spa technician".


"It's getting a little bit warm."


PROBLEMS

POSSIBLE CAUSES

SOLUTIONS

No heat at all Tripped hi-limit switch Locate and reset.
Open doors on spa cabinet Close the doors.
Pilot light went out (gas heaters) Relight pilot light as per owners manual.
Pump isn't pumping any or enough water Determine problem and repair (see section on pumps and filters).
Heater cycling on and off continuously. Dirty filter Clean filter cartridge, if in doubt try running the system with the cartridge removed.
Low water level in spa Raise water level.

Takes a long time to heat spa.

 

Dirty filter

Clean filter cartridge, if in doubt try running the system with the cartridge removed.

Daily filtration and heating cycle not running long enough

Reset time clock.

Damaged Insulating cover Many spas, especially electrically heated wont heat up without a proper cover. Repair or replace.
Bad thermostat Replace if necessary.
Hi-limit switch turning off heater prematurely Replace if necessary.
Pilot goes out (gas heaters) Weak pilot generator Replace pilot generator or assembly.
Restricted pilot Clean pilot.
Outer jacket very hot (gas heaters) Sooting of heat exchanger Determine cause of sooting, clean and correct (the most common reason for this is too much water flowing through the heater causedby either too large a pump or internal heater parts damaged).
Improper venting Follow recommended installation instructions.
Insects or debris cloggingburner intake ports Clean burners.
Leaking at heater Improper water chemistry Determine exact location and cause of leak, replace damaged parts and maintain proper water chemistry.
Harmonics, whining or banging noise Debris or restriction in system Locate the restriction and remove.
Low flow Determine problem and repair (see section on filters).

WARNING

Use any of the information contained herein AT YOUR OWN RISK. These instructions are primarily intended for use by qualified personnel specifically trained and experienced in the installation and repair of spas, electrical equipment and related system components. Installation and service personnel may be required by some states to be licensed. Persons not qualified should not attempt to install this equipment nor attempt repairs according to these instructions. Please remember that water and electricity DO NOT MIX. If you are not capable of performing a repair yourself, please contact a local spa professional or a licensed electrician in your area.This information is presented for informational purposes only, and we will not be held liable for any injuries that may result from the troubleshooting or installation of any electrical components in your hot tub or spa.


If you need an exploded view / parts list & diagram of a particular heater, below are links to various pictures we have posted here so far. If the heater you're looking isn't listed, just drop us an Email and we'll put it up here for you. If you need a specific part, let us know.

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