even with the power off, then it’s likely the board. What can happen is the heater 
relay although closed and apply voltage to the heater, it’s not allowing enough 
current to reach the heater element. To determine if that is the problem, you need 
to test the amperage draw when the heater is on.  
 
What the spa tech will do is use his meter set to AMPS and test one hot wire to 
the spa. He will note the amperage draw when the pump comes on. Then when 
the board turns on the heater and the heater light is solid he will notice the meter 
show a large demand again. If so, the heater should be heating. Yours would not. 
But if you don’t have a meter to check the amps or do not know how to, if you 
have come to this point and can’t check the amps, then you should expect the 
board to be the cause of the heater failure. 
 
IF the heater light does NOT come on or is flashing, that means there is a failure. 
See the “CODES” failure section. 
 
 
Why do Heaters Fail? 
 
Heaters tend to fail one of two ways. They no longer pass current through the 
element and therefore no longer heat.  
 
The most common cause of this failure is water quality. Over time water quality 
can cause the element to “leak” current and cause the GFCI to shut down the 
spa.  The manufacturers of elements insist that if the water is kept to “optimum” 
levels that the element should last forever. Their claim is that the only thing that 
will harm an element is the on/off of the electrical current to the heater and poor 
water quality that damages the element itself.  
 
Their claim is paralleled to a light bulb. If you leave a light on and do not turn if off, 
it will last a long time. It’s the initial startup that causes the bulb to fail (that’s why 
this flash when you turn them on). The element on the heater is supposed to have 
the same problem. Since they will literally be turned on/off throughout the day 
over the years, they fail. That along with the water quality determines the longevity 
of the heater. 
 
Therefore you can extend the life of your spa by making sure the top and sides of 
the spa are insulated well (to lower heat lost) and keep the water chemistry