Laars Lite LD 325N heater may require new Gas Valve.

[drew7ster]

HI all, I have a Laars Lite 2 LD325N heater. Worked through all problems last years, and only bringing it online now for 2019. Heater started and ran, but I was encountering pounding or banging and then I shut the heater down to investigate. I was led to understand that the waterflow may be restricted, which suggests that there was some debri in the lines. I opened the heater drains and pumped water, then opened the 2" line from the heater and again ran the pump. No issues, and no visual constraints on waterflow. I walked though the Jandy trouble shooting guide from
https://www.fwwebb.com/docs/gas/JandyPoolHeaterTroubleshootingGuides.pdf. I had no issues in getting 24VAC throughout except for the voltage at the VAL terminal on the ignition control. Based on the fact that this worked a day ago, I assumed that the ignition control is functional. The final step (step 9) is "Does the heater fire?" And, no it does not (not now anyway). So, if everything works, then I need to replace the gas valve. Otherwise, replace the ignition control. Does anyone have any experience with this particular problem? I am loath to blow money on a part that doesn't fix the problem. Thanks, Drew7ster

 

[Soupy]

Measure voltage at the valve itself. If you have 24V and the valve doesn’t open, it’s the valve. I had this issue at the start of last season, and gently tapping the valve with a rubber mallet got the solenoid to move and valve to open... hasn’t gotten stuck since, knock on wood.

 

[drew7ster]

Thanks Soupy. I went through the complete troubleshooting guide, and found no issues, thus I was guided to replace the gas valve. I noticed that although the heater had worked (haltingly) for a few minutes, the gas valve had a crack in it. I found a new unit on Ebay for $100, took out a $15 warranty (2 years), then replaced the unit. I also note that the opening instructions in the Owners manual says to put 50cc of SAE 50 oil into the anti-siphon loop for the pressure switch. I had to replace the entire line and reconfigure for an anti-siphon loop, but finally completed the task today and its working great.