The problem is not the heater. When was the last time that you cleaned the pool filter? Low or no water flow - no heat. Low flow = dirty filter or plugged pump or skimmer baskets.
Ken
Use the link below to look at a Laars manual to see if one is included.
Try this link www.jandy.com Ken
Check that you are getting voltage from the thermocouple. You should see about 600 millivolts.
I cannot find a current listing for Teledyne Laars. As far as I can tell, Teledyne and Laars separated, Laars joined up with Waterpik and then got reorganized under Jandy. www.jandy.com now has the Laars Lite2 line of pool heaters with the LG model almost identical to the Teledyne Laars LLG. You can access the manual at http://www.jandy.com/pdfs/H02359-.pdf . Jandy also has a parts list for older discontinued models.
go to their website and support and download it
You might want to try Jandy.com k
You can find every part you need for your boiler at gasboilerspareparts.com
Try google Jandy.com
it makes sure the heater is shut down BEFORE the pump does. It is very important if the heater runs without the pump running the water will boil in the lines and burn out the heater. I know this because my electrician didnt wire mine correctly and that's what happened to me. BYE BYE 2,500 heater
Write or inquire thru that web site for a manual to be sent to you. k
Spa not getting to temp? Could be a dirty filter. Could be a high limit switch or other component.
Use the manual provided with the heater. Each heater has somewhat different controls etc. If everything is already hooked up you may just have to turn a switch or two and turn up the thermostat.