Laars LX400N wont ignite

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  #1  
Old 07-31-19, 08:54 AM
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Laars LX400N wont ignite

LX400N pool heater will not ignite. Unit goes through startup process (blower comes on) but hot surface ignitor does not glow (normally the next step in the process). The gas valve does open though. I hear the click and odor of gas.

I used a troubleshooting guide and tested all the wires on the safety loop terminal bar and all show current during startup.

Measure resistance of the HSI and it is 67ohms

Measured voltage from the ignition control to the HSI and it reads 118v

Why the heck is this thing not glowing/lighting the heater? Advice from someone would be appreciated...thanks
 
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Old 07-07-20, 10:38 AM
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Did you resolve your HSI issue? I am having the same problem. I had a bad HSI for sure, which I replaced, but I am still having the same issue. New HSI measure 50 ohms. It goes through 3 full start up cycles which results in an AGS fault. Like you I get a whiff of gas but no flame. Any thoughts you can share? Thanks.
 
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Old 07-07-20, 11:33 AM
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Welcome to the forums..... both members....... (For some reason I missed this originally. )

If there is gas coming out..... the safety sensor loop is ok.
When you check for 120v to the igniter..... it needs to be connected during testing.
 
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Old 07-07-20, 01:18 PM
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Thank you. I have a battery powered viewer that lets me see into the combustion chamber through the glass view-port. When I activate its light I can clearly see inside. I assume that without the light I should be able to see the HSI (igniter) glowing when the gas valve opens, but it doesn't. I replaced the originator igniter because I was getting an AGS fault and it tested completely open. My new igniter is measuring 50 ohms so it's good but not getting 110 volts. I'm still getting that AGS fault. When I unplug the igniter and put my meter on the source leads I get no voltage when the igniter should be active. Maybe the controller is smart enough to see it isn't connected to the igniter. Is that the case? Do you think this is an ignition control failure? Any other thoughts? Thank you again.

On Edit: I just looked closer at the ignition control module. It controls 240 VAC and there is no neutral available so I assume the igniter must also be 240. There is an LED on the module and it is off and not flashing any codes. I will check tomorrow, when it's cooler, to verify it is getting the 24 VAC it requires to function. I am wondering if the igniter failed and caused the control module to fail, or possibly the other way around.
 

Last edited by JohnASmith99; 07-07-20 at 02:47 PM.
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Old 07-07-20, 03:59 PM
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The igniter control doesn't monitor the igniter.

On a call for heating.... the inducer runs, activates the pressure switch, igniter heats up and gas valve opens. If you aren't getting the 120v.... the control module is bad.
 
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Old 07-09-20, 01:10 PM
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Thank you. I am trying to locate the correct replacement. None have the exact model number and the prices vary wildly. Most have exactly the same specs but with one or more different labels. I found one with the same labels except for one of the connections. Mine says PS while the replacement says IND. I have no idea what either mean but hopefully you can tell me if it matters. The model # is also very close. Can you tell me what PS TH and VAL do. It appears the FS is the flame detector right? Thanks again, you have been very helpful.


My Ignition Module


Possible replacement module
 

Last edited by JohnASmith99; 07-09-20 at 01:59 PM.
  #7  
Old 07-10-20, 10:45 AM
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According to Laars..... E0253400 is the replacement ignition board.
Yes..... I see the prices are all over the place. The link is a great price.

Laars 24v ignition module

 
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Old 07-10-20, 12:22 PM
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WOW, that is a great price! Just to confirm, the PS connector on mine is the same as PSW on the replacement, right? Also, the TH and PSW connectors are reversed from mine so I would obviously reverse my wire to match, right? Stupid questions I know but I don't want to mess up. Thanks again.

 
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Old 07-10-20, 08:52 PM
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You have ....... PS = purple and TH = black/yellow.
Did you have those wires off ?
I think they may be on backwards.
Is there a wiring diagram you can post ?

See if this downloadable manual is your manual.

 
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Old 07-11-20, 11:38 AM
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My PS is purple and TH black/yellow but flipped from the photo on SupplyHouse. I will order it and see.


 
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Old 07-11-20, 11:48 AM
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I'm going by the schematic. Did you have the wires off the box ?
 
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Old 07-18-20, 01:15 PM
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I hope you don't get tired of helping me. I went ahead and purchased the LAARS E0253400. Another issue though, it is designed for a plug in harness where my original uses individual push on connectors. Now I need a harness! Any thoughts where I might get one? I attached a photo of what I think they look like.

 
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Old 07-23-20, 07:28 PM
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I never get tired of helping. I travel thru many forums and don't always see a new post.
Feel free to bump a thread.

You need a Fenwal Controls 05128981024 wiring harness mate. You can search using that part number for best price. Left link to part at amazon.

Harness on amazon
 
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Old 07-24-20, 03:44 PM
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Thank you Pete. I ordered the one on Amazon, looks perfect.
 
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Old 07-30-20, 08:49 PM
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I just received the needed wiring harness and have now installed the new ignition controller. It works!!!!! Thank you, thank you and thank you again Pete. I searched everywhere trying to find the info you provided and no one else was able to help. My next pool project is upgrading my broken AquaLink PDA to the iAquaLink 2.0 iQ20-RS.
 
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