Pool heaters are needed to help keep the pool water at a comfortable temperature. A Teledyne laars series 2 model esg pool manual is usually available with the manufacture.
Here is the file
http://i.poolproducts.com/pdf/XL3_manual.pdf
http://www.jandy.com/html/productsupport/#manuals
go to their website and support and download it
Write or inquire thru that web site for a manual to be sent to you. k
Try this link www.jandy.com Ken
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.
Try google Jandy.com
You might want to try Jandy.com k
You can find every part you need for your boiler at gasboilerspareparts.com
Lighting this heater appears to have a number of warning messages associated with it. It is typically best to go to the source for such things, so see the link below for the manual PDF file. Look at page 29.
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.
Oder the part from the company, a different orifice
Use the link below to look at a Laars manual to see if one is included.
Probably a bad sensor. Have a professional diagnose the problem. It can be very dangerous for untrained to work on gas appliances.