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Hot Tubs most commonly use 3 rating of heaters and a variety of sizes and styles.

Simply stated, the heater is an element that when electrical current applies to it, it resists the current and doing so creates heat. Because the element resides in the hot tub water you can destroy an element in less than a year or with water care, extend the life to over 5 or more years. The average is 3-5 years. Since the element is in the water, it's the #1 cause of the gfci popping. You must replace heater if its the cause of a popping gfci. Sometimes you see corroding heater posts, sometimes on the element itself, and many times the "short" is hard to see. What is happening is the electrical current is leaking from the heater element into the water and the gfci is sensing it and shutting off the hot tub. That is GOOD. Means you will not be shocked or electrocuted.

The ratings of the heater is designed to match the current you supply the hot tub with the heater current draw. A 110-120vac hot tub has either a 1.5kw heater (heats 1-2 degrees per hour) or a 4-5.5kw heater (heats 2-3 degrees per hour). The most common hot tub is designed to operate on 220-240vac. These heaters are 5.5 kw heaters which is the industry standard. You should expect about 5-6 degrees per hour temperature increase when the heater is operating correctly.

Its common for hot tubs to placed their heater in a steel tube below the control box, behind the control box, in the control box, and on a few models on the side of the control box.

Why did my heater last such a short time? This is a common question so I'll cover it. The element is designed to be in balanced, quality hot tub water. I see heaters lasting 7-8 years or even more. That tells me the owner takes care of their water OR it's from a great water source. I would expect to get about 4-5 years on a heater in most areas. If lower, first look at your own water checking habits. Often when repairing a hot tub with a local customer they will insist they check the hot tub water weekly but by the end of the conversation they admit they check occasionally and probably didn't get it right. That is why I always recommend a good relationship with a local hot tub store that knows the local water and how to balance and maintain.

The 2nd reason heaters fail: water source. Many water sources are HARD water, mostly calcium/magnesium. Those minerals attach to the element and cause it to fail. With a local, quality dealer that supplies chemicals they can walk you through dealing with local water. If your water source is surface water usually its easier to maintain. If your water is well water, the hardness can be hard to overcome. But this again helps us to understand having a local retailer walking you and checking your work will give you longevity with your heater. One manufacturer of heaters claim if the customer keeps their water quality HIGH that the heater will last for a long, long time. In theory, perfect water will never harm a heater element and the heater will work until the heater itself breaks down. How to Test a Heater? Heaters work by resistance.

To test a heater you must be able to use a volt/ohm meter. See Here With hot tub's power OFF, set the meter to OHMS. Place one probe on each heater post. You should have 10-15 ohms resistance. If not, you heater has likely failed.