utica gas boilers burning up thermocoupling

Paul_69

i am a tech and have a 25 yr oil gas boiler m- 75 that has a horizontal thermocoupling and i replaced it 3 months ago. i went back and it seems like the pilot is large and makes the t coupler burn cherry red. the bracket that it screws into also is hot from pilot and distorts aluminum threads.can pilot be lowered or does this unit need a husky thermocoupling?i have seen alot of posts about similar problems. tim can you give any advice

Tim McElwain

Is this an oil

boiler converted to gas? If so what conversion burner does it have?



As far as the thermocouple glowing "cherry red" hook up a millivolt meter to the thermocouple and then adjust the pilot gas so it glows dull red, this will give you about 30 millivolts. Better than a "Husky" get a Jonhson (Baso Gas Controls LLC now)K16LRA nickel plated high temperature thermocouple.

Paul_69

atmosheric gas boiler

tim it is a atmosphric gas boiler.the thermocouple goes in horizontal and the flame from pilot goes underneath the thermocouple which i have never seen this on a boiler before. everything i have seen is vertical. this pilot seems to really bake this thermocouple really bright cherry red. i will take your advice on adjusting pilot. i have seen many posts with other techs with same trouble with these old uticas that have horizontal thermocouples.  thanks

Paul_69

test

tim when you test operating millivolts do you have pilot on and one lead on tip of thermocouple and other lead on outside of copper lead and it disconnected at gas valve?? thx

Tim McElwain

Yes Paul

that is the correct procedure for testing the "open circuit" output of the thermocouple. The entire procedure is available here by going to "RESOURCES/LIBRARY" above and then look for Tim McElwains Closet.