I have a spa heater that does not come on. It is a LAARS Lite model LLD2500N. I have replaced the ignition module and the igniter. The module, transformer and the thermostat is getting the proper current. I have bled the gas line to inure gas flow. After I set the dials at the proper settings for the heater to come on, it does nothing. The module should make a ticking sound (igniter) which it does not. Please help. All suggestions would be appreciated.

 

If heater won't spark then there is an issue in the safety loop more than likely. Pressure switch, high limit, roll out sensor, thermostat. You can bypass these one at a time with a small piece of wire and see if it will fire. You can also try jumping the gas valve to see if it will fire.

NEVER LEAVE ANY JUMPERS IN PLACE AFTER TESTING

If you want to try this and need more help let me know.

 

There are two high limit switches on the manifold where the water inlet is. As Todrut says, they can simply be bypassed with a jumper to see if they are causing the problem.

Also, there is a pressure switch inside the electronics compartment that can also be bypassed with a jumper. If that turns out to be the problem it could simply be not enough circulation indicating your filter is partially clogged up. Backwash or change the filter before you change the pressure switch.'

Then there is the thermistor that is in a drywell in the water intake manifold. The only safe check for this is an ohmmeter, and it requires the ability to change the water temp during the test and having the chart of ohms to resistance. You can simply make a jump on the thermostat board to bypass the thermistor but one small mistake and you fry the circuit board so don't even consider it... If bypassing the safety switches doesn't locate your problem then call a pro. Otherwise you will end up replacing even more than you have.