Earlier today, I tried to connect a timer up to my spa motor so that I can set it to automatically run the filter for a couple of hours during the afternoon.
My spa is an older Cal Spas model with manual, electromechanical controls. Because of the limitations of the standard household outlet, the span heater and the jets cannot be operated at the same time. The manufacturer uses a SPDT switch on the "jets" button that disconnects power from the heater when the jets are turned on.
In order to have the heater automatically disconnect when the jets/filter motor is turned on by the timer, I decided to use a relay. I connected the coil of the relay to the switched output of the timer and connected the hot conductor for the heater to the normally closed contacts on the relay.
I'm using a relay with a 120 VAC coil and contacts rated at 30A and 120 VAC. When the timer engages the motor and the coil, the heater switches off as planned. When the coil is disengaged, however, I hear a series of loud clicks - about 4 or 5 - before the heater re-engages. Something told me that this is "no good", so I disconnected the power. The relay felt quite hot to the touch.
My question is this, shouldn't a relay rated at 30 amps be able to handle the load of the heater? After all, power to the spa is provided by a standard 120 V outlet. I'm fairly certain that a standard outlet doesn't provide more than 15 or 20 amps. Perhaps I didn't crimp one of the conductors properly?