I have tropic isle c120 heater for spa, burners do not fire when pump turned on. New pressure switch put on after jumping switch. water seems to run freely through pumps. Pressure at filter is 100.

SOURCE: No Heat from Spa

Tcarrigan,

Heater contactors "buzzing": Do you mean normal buzzing or extra loud buzzing? Loud buzzing or chattering can be caused by low voltage to a contactor. If normal sounds, then probably the relays on the contactors is working, but the contacts may be stuck, or burned enough so as not to make contact. First, get a voltmeter and check for 240 volts AC at the heater contactor terminals. If the voltage is low, most likely you need to check the contactors further. Check for dirty contacts, clean if needed. If the contacts are not moving when energized, then you will probably need to replace one or both of the contactors.

SOURCE: Spa water drains to pool

Here is a link to the Aqualink website so you can download a trouble shooting guide.

SOURCE: We just moved into our home and there is no manual

Here is a link for the Manual and trouble shooting guide. Aqualink

SOURCE: The heater makes a banging sound after the burners

What you have is a water flow problem. The water should be going through the heater but it is by-passing it. The water inside the heater is boiling and trying to expand as steam that makes the banging sound. Their is a internal by pass in the water manifold on the side of the heater. If you take this apart you will find a disc on a spring contraption, if it is stuck open the water goes past the heater but still has pressure to kick the pressure switch and fire the heater. Either clean or replace this assembly. The other thing to check for is an external by-pass. This will be a gate valve bridging the inlet and outlet pipes. If you have one of these it should be 80-90% closed or the water goes through it and creates the same problem. This is not on all systems so don't be alarmed if you don't find it. Good luck.

SOURCE: heater will fire up, but only run for about five

Possibly poor water flow. Clean all the baskets, pump too and backwash/clean the filter. If water flow is ok it might be the temperature control. If you are running it on "pool" try using the "spa" control...