low water cut off sensor

ratbone

yearly inspection revealed low water sensor no good, water adder no good. some personal digging showed that the water adder was plugged up but as it was an add on to a manual water adding system i could add water when needed and it the furnace worked just fine. further sleuthing made me aware that when water did get too low the solenoid activating the auto feeder was working fine. big loud snap, no water due to plug, but trying hard to work. that made me wonder if the same sensor activating the water adder would also keep the boiler from running without, ie that the low water sensor was at least okay some of the time. as an experiment i watched the water disappear from the observation tube and in a few minutes the boiler shut itself down. seems to work. the company we use for oil and all things furnace related is one of the big ones locally with a good reputation. could they have made a mistake in the diagnosis? could this low temperature shut off switch work some of the time and need replacement as not completely broken but unreliable? i know you guys are quick to defend your other operators. i was badly ripped by one of the bad ones. he replaced the oil pump for $$$ when what i really need was a tiger loop. that $$$ is gone but i still am a bit more careful, perhaps paranoid. i did later find that that company had a reputation for this kind of thing. so what i would like from this forum is an answer to my technical question about the low water sensor switch and also should i get a 2nd opinion on the system? your forum suggests only one contractor in my state who is too far i think for a consult but i could get another local company to come and look if that seems the safe way to proceed.

EBEBRATT-Ed

You have to be careful with Low water cutoffs. I am assuming this is a steam boiler.

A low water cutoff is a safety devise to shut the burner down if the water gets too low. If the water is below the bottom of the gage glass the boiler shouldn't be run and it should not be run without a dependable low water cutoff.

All the above is to protect you and the boiler because you don't want to have to replace the boiler because the low water control fails. And their (the low water cutoff) usual problems are from dirt and sludge.

And yes the same low water control usually activates the water feeder.

The control can usually be removed and replaced and or cleaned & serviced but since I can't see what you have I can't advise on that. You could post some pictures

ratbone

i neglected to mention that the unit had not fired for at least 7 months when the service guy did his testing. thinking now that maybe sedentary sludge prevented the operation at first but heat and agitation have restored the mechanism to good operation.

KC_Jones

Your picture is a bit weird, but I can make out the float type Low Water Cutoff, so I have a few questions.

1. Do you blow it down every week during the season?
2. When you blow it down do you do it while the burner is running to verify proper operation of the unit?
3. Does the service company disassemble and service that unit during yearly service like they are supposed to?
4. How old is the unit? Replacement is recommended every 10 years.

EBEBRATT-Ed

@ratbone

What @KC_Jones mentions are good points. Just because the LWCO works today does not mean it will work tomorrow or the next day when you need it.

Strongly advise you or your service company take it apart and clean it and make sure you get good flow through the gauge glass tapping's. I would also take the pressure control off the pigtail and make sure the pigtail is cleaned.

ratbone

KC_Jones
answering your very good questions
1 two years ago i did not blow out the system before the summer. when tested in november the unit was plugged and inoperable. the tech cleaned it and replaced the float.
2 never thought of this but now i get it and have used this procedure to see that the sensor now works and shuts the gun right down. very exciting steam event! (grand children)
3 i believe they do not but plan to discuss with the company when i get all my ducks in a row
4. the casting is about ten years old (whole new system at that point) but, as mentioned, float replaced recently

other facts re this system. we mostly stay warm with wood. running an hour in the morning is enough for all but the coldest days. for years i burnt 24 x 13 inch logs in the basement but this old body is no longer capable of such activity. my point is that we burn about 300 gallons of oil on a yearly basis.