thermal couples

Bill Gripp

Wondering what would cause a steam boiler to go through five thermal couples in one heating season? Boiler is a Utica model peg 112b2. Pilot flame is a good height and boiler is not that old. This has been a problem for a few years. going through anywhere from two to six thermal couples a heating season. I'm stumped.

BillW@honeywell

Premature thermocouple failure

You might want to try the heavy-duty Q340 thermocouple. Make sure that the pilot flame covers from 1/8 to 1/2 inch of the t'couple. You can do this by adjusting the pilot adjustment screw on the gas valve. Check the gas pressure too. DO NOT try any of these adjustments if you are a homeowner! Call a service company, or use the "Find a Contractor" feature above

Boilerpro_3

Also,

Check to see if the flame from the main burners are hitting the thermocouple....I bet that won't help life easier. I'd also measure the Millivolts coming out of the thermocouple. Most of those I've seen lately are up at 40 to 50 MV because the pilot adjustemnt is full open from the factory. If it needs to be adjusted down, typically five full turns down are needed before there is any effect on the pilot output on many common Honeywell gas valves used on boilers.

Boilerpro

Unknown

What kind of thermocouple

was able to give 40 to 50 millivolts. I have never had one that I could get that much out of it. That is really good if you get it that high.

kf_2

Utica

Bill,

Utica is well aware of that problem on those boilers and they do have a fix. Unfortunatley it has been so long since I have had to fix one I can't remember what it was.

But call Pete Desens at Utica. I'm sure he will be able to help. 1-800-325-5479 or 1-315-797-1310.

kf

Unknown

Thermocouples

There was a prevoius post on "Thermocouple Failure" in it I posted some info on trouiblshooting thrmocouples. I will bring it back up for you.

My experience with Honeywell Q 340 thermocouples has not been as good as the nickel plated Johnson K16RA thermoccople.

Boilerpro_3

Johnson Controls \"Husky\" with too big of a pilot

Unknown

With the high

millivolts what was your closed circuit reading? How long do they last with that high a reading? What kind of equipment was this on? What was the Honeywell gas valve and if you know what make of pilot and the orifice size? Sorry for all the questions but this really has my attention with such high millivolts. The most I have ever seen was 40 millivolts, and that is rare.

Boilerpro_3

Sorry Tim, still haven't got a testing block...

Same gas valves that you helped me with before, Honeywell VR8200/ 8300 with 1/4 inch pilot tubes with the standard hooded Honeywell Q 314A type pilot. The valves are on Lochinvar RBN and Dunkirk Plymouth or Dunkirk Extreme boilers. Gas line pressure at the valves was around 6 to 7 inches pressure... high pressure gas mains are the norm in Northern Illinois. As to life, hard to say. Most of them I checked after replacing the original TC's and then
adjusted the pilots. The pilot flame has to be very small to get these TC's down to 30 MV open. They are not glowing at all when adjusted, so I imagine you would get good life at higher outputs with a larger flame.

Boilerpro

tim from Reed Wright

t-couples

best ones we have used for years are johnson controls k16bt-36 t-couples. Best outputs and held up best. They don't always fit all pilots but if they will do it. We probably put in close to 500+ a year.

Unknown

Tim do you use

their "Super Slim Jim" K19AT version for those pilots that the Husky will not fit? If not you might try it. I have found over the years one or the other of those two thermocouples handle just about any job.

Mark J Strawcutter

are thermal couples

another name for newlyweds?

Mark