Low Water Cutoff Probe - RUST!

Boiler Talk

My oil company who services the boiler apparently never checks the LWC probe. I did it today and this is what I find. Rust! I think this is due to the looseness of the nut on the probe itself. I was able to be turn the probe with my fingers!

I haven't taken this probe completely apart to see how it is constructed or if it can be serviced more than tightening the nut. I had an earlier probe replaced and installed that, but it was in better shape and still works!

The rust in the LWC box is superficial. Any helpful comments about the use of the pictured probe would be appreciated. I think a new one is probably a better idea, but then the rust seems minor.

Boiler Talk

EdTheHeaterMan

You can purchase the “probe only” in most cases.  Or you can attempt to take the metal rod apart from the porcelain insulator.  There should be an "O" ring or other gasket sealing material that may be replaceable, but I myself have never tried that.  I sometimes replace a bad control on the existing probe, leaving me with a spare probe on my service truck for a future time when I have a working control with a leaking probe. 

I have replaced leaking probes successfully in the past several times.

Boiler Talk

Thanks, Ed. I think my earlier provider may have had an extra probe, because I don't recall a charge. I now think the probe has too much rust. I tightened the replacement probe nut a small amount to be sure the probe will not spin/turn. Now I will have to look in few weeks at the thing.

clammy

Date code on your lwco seems to indiated it was manufactured in march 2011 according to safeguard i believe they suggest replacement of the whole unit every 5 years at least w a cycle guard . Generally i pull the probe and clean when doing yearly maintenance aside from being sure that it cycles the burner off when water level is dropped . I have found cycle guards which operate properly on the cycle end but would not shut the boiler down when firing with a below proper operating water level . So remember to have your boiler running and while firing drain out some water of the boiler to the point where the low water cut off shuts the burner off if it does not do so replace the whole unit . As expensive as you may think it is its 1/2 the price of the cheapest mech float type low cut off and with out testing either when they fail your liable to be replacing your boiler ,so be sure its working properly . I usually replace probes that show signs of leakage and or cannot be cleaned as the mud is encrusted into the sensor .

peace and good luck clammy

Boiler Talk

Thanks. I did purchase the probe. I will test on fire and lower the water.