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Laars Lite II LD400N - Pressure Switch Issue ?

Laars Lite II LD400N - Pressure Switch Issue ?

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  #1  
Old 05-20-15, 01:09 PM
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Laars Lite II LD400N - Pressure Switch Issue ?

Hi All. I have a LD400N natural gas fed heater on my 26k gallon pool. 12th season here in PA. Heater will not startup and stay lit. I suspected the pressure switch because I had to load the loop up with oil last year to get it started, which I did again this year but it did not result in normal operations. I bypassed the pressure switch and got the electronic ignited going followed by the "click" and one quick ignition of the burners which only lasted a second, nothing sustained.

First off, is there a proper way to add oil to the siphon loop? Can I use household 3 in 1 oil?
Second, with the pressure bypassed, shouldn't I get normal start up or is it obvious I have something else wrong? Not sure if the PS provided some other cut out signal to prevent operation.

I'm going to go home and make sure there is water flow through the loop to the PS. I had to deal with a filter grid problem at startup and there was loose DE in the system. I get a sucking sound when I disconnect the loop connector now, without the pool pump running.

Any ideas or insights would be greatly appreciated.
 
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  #2  
Old 05-20-15, 09:46 PM
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Welcome to the forums.

First off... 3in1 oil is way too thin for that application. The manufacturer specifies 5cc, about 1 tsp full, of 50 weight non-detergent oil.

As far as your problem.... did the burner try to light by itself or not until you bypassed the pressure switch ?
If it didn't light until you bypassed the pressure switch then that switch could be bad.
If it did light but not stay lit then you probably have a dirty flame sensor rod. You can pull it out and clean it with steel wool or a scotch brite pad to get it nice and shiny.

A link to your manual....... Laars Lite II manual.PDF
 
  #3  
Old 05-21-15, 10:46 AM
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Thanks.
I'll try to add the 5cc of 50w in the siphon loop and clean the sensor rod.
The sensor rod may be the reason it didn't stay lit in bypass mode.
 
  #4  
Old 05-28-15, 12:45 PM
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Other ideas

I replaced the pressure switch and now get the heater to consistently try to light. I observe the HSI doing its thing, a click, and most times I get the burners going along the back for 2-3 seconds and then go out. Three attempts at that and then I cycle the on-off switch. I was going to go after cleaning the flame sensor, but with only the back flaming initially I dont see how the flame sensor is positioned closer to the front. Does the flame sensor need to respond that quick, within 2-3 seconds of ignition?

My next plan is to pull the tray out and clean it out and clean the flame sensor while I'm there.

Are there any other components that would be suspect based on my description?
 
  #5  
Old 05-28-15, 06:42 PM
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It sounds like the burner isn't lighting fast enough after receiving gas. That could be caused by a dirty/rust clogged burner or a clogged orifice.
 
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