Laars Lite 2: Flame Sensor issue

[NOVApool]

Okay so update from my end:

Installed the new flame sensor and used a wire brush on the various terminals and connection points. I did note that some areas seemed cleaner than others, should I be using some sort of solvent at this point to completely remove the corrosion?

As for my testing, I tested the system without the flame sensor plugged in, and it kept running. I also tested the system with the flame sensor plugged in, and it also ran fine. However, I performed some additional tests where I had the gas line closed, and I clearly heard the system attempt to start, shut off, and then attempt a restart. (3 cycles total) I also ran a test where I would start the system normally, and after the flame started, close the gas line, and about a second later heard the system shut down, and then attempt relight procedures.

My question is: is there any other sensor that could be shutting down the system beyond the flame sensor? It seems very counterituitive to me, but it seems like the system does in fact run properly when the flame sensor is plugged in. However, for some reason when there is no flame sensor, the system doesn't seem to care and won't be shut down on that basis. In sum, I think my system is in fact working properly as long as a flame sensor is plugged in.

Thoughts?

 

[swamprat69]

Any of the other safeties in your system will also shut down the heater. Since your heater came with a separate flame sensor installed to protect against "iffy" flame sensing using only an ignitor, leave it in. Solvent won't completely remove corrosion, you could try a small diamond file (sold in sets at harbor freight or amazon). It seems that your system and Fenwal ignition control are operating normally. Again, at this point in time I wouldn't advise any major expensive repairs to the heater due to its age.

 

[NOVApool]

Oh I should clarify: I am certainly NOT suggesting that I would take out the flame sensor. I'm just trying to make sure that you agree with my above tests, namely that when the flame sensor is plugged it, it is in fact the flame sensor that is shutting the system down, and not some other fail safe. The only other test I can think of would be to intentionally block the single orifice that runs to flame sensor, and see if the other burners light up for 1-2 seconds, but then the system shuts down because flame sensor burner has no flames.

Anyway, based on all this, would you also recommend that I install a new gas valve? I can't seem to find any sort of date stamp on it, and, as the other poster pointed out, there is definitely enough water down there to cause significant corrosion.

Lastly, I've said this before but I'll say it again: THANK YOU FOR ALL YOUR HELP!!! I'm working from home with young children around so every minute you've saved me has been a godsend.

 

[swamprat69]

If you have water in the burner section, the heater is really on its way out if you heat exchanger leak (major expense to replace). Try to get through this season anyway. Your welcome, glad I could be of some help.