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Bob Tonner
Bob Tonner Member Posts: 64
No, I cannot recommend anything better in the way of analogue gauges.

InfinityLab has a control in development that will digitally display the temperature, and I think that Erie has a product called the Boiler Boss that displays temperature digitally, but I am not sure about the accuracy or the availability.

Best regards

Bob Tonner

President, InfinityLab Inc.


  • sootmonkey
    sootmonkey Member Posts: 158

    Bill, I work for an oil company in Maine. I do mostly tune up and inspetions on oil fired equpment. My experence is 1 year of tech. school and 3 years in the field. I have noticed on many/most boilers that the 8124 control will over ride by as much as 20 degrees. My own boiler overrides by 15 degrees. I have pulled the control off and made sure that the probe is all the way in the well. No different. I repulled the control and applied the heat transfer grease. No difference. (On another system I did the same thing and also cleaned the water side of the well, after replaceing the coil gasket) I now just keep the control turned down. I have concidered the fact that the well and the temp/pressure guage are not sencing the exact same spot of the water, but am not sure if that would be it. Any thoughts?
  • Quick questions

    What is the boiler outlet temp at the supply? What is the return temp? What is the gauge temp? What is the Aquastat temp setpoint?

    If you have a slow flow and a large temp rise through the boiler, these numbers can get farther apart.

    If you have a 5 or 10 degree rise through the boiler and the aquastat acts way outside that range, the control is off. If it repeats at the same point every time, it could just be a calibration thing.

  • sootmonkey
    sootmonkey Member Posts: 158

    Unknown supply/return temp. Aquastat is set at high 180, low 150. diff is 25. right now temp guage is at 200 with no call for heat. Boiler is Burnham v73. It I see the "overrides" on all brands of boilers
  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099

    Can you tell me which model you have? In a low limit/circ control, on temperature rise, with the adjustable differential set at min setting (10 degrees) R-B (burner circuit) breaks and the circ circuit (R-W) makes at the control setpoint. Once the temp drops to 10 degrees below the setpoint, R-B makes, starting the burner, and R-W breaks. If you set the differential higher than 10 degrees, R-B make temp and R-W temp will remain the same, but the R-B break and the R-W make will be the set point temp plus the difference between the differential setting and 10 degrees. Confused yet? Here's an example...set point 140, differential set 25 degrees. On temp rise,R-B will break snd R-W will make at 155 degrees. Temp fall, R-B will make and R-W will break at 130 degrees.

    If you have access to a computer, you can download a tech sheet at http://hbctechlit.honeywell.com.

    Noel, thanks for the backup. As Noel said, other factors can influence the control's performance. If you can, get me a date code, a 4 digit number usually in the cover on on the control somewhere , a number would be 9853 or something like that. I hope this helps you.
  • sootmonkey
    sootmonkey Member Posts: 158

    Bill, That piece of paper that was floating around on the inside of the control got thrown out long ago. Real men don't need instructions or part numbers:}, Just joking,I read all instructions. I belive that the control is a L8124C. The boiler was installed in 1992. This is the orginal control. Could it be a calibration thing? In my experence, It is a rare system that has a control and temp guage that agree. The 30 year men at work say "Don't worry about it, just turn the controls down a little." I'm not to worried about this, just thought you might have an idea.
  • sootmonkey
    sootmonkey Member Posts: 158

    Yes, I guess that my control is overriding by 35 degrees.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    old news

    here. Quite often I see 20 degrees out of calibration and have to compensate. Another one of those irritating things about boiler non-presicion..

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  • Bob Tonner
    Bob Tonner Member Posts: 64
    Don't believe the guages....

    A few interesting things that everyone ought to know...

    In our lab we embed a calibrated thermocouple into the sensing probe that gets inserted into the well during our research. As a result we get a highly accurate display of the temperature that the sensor is seeing at all times. It is very common to see a 20 degree F spread between our thermocouple and the analog guage on the boiler.

    The UL 353 standard allows for a 15 F (or 5%, whichever is greater) tolerance on the high limit setpoint versus the actual temperature at which the control shuts off.

    The Standard also allows for a "scale error" on the dials associated with each setting.

    Bob Tonner

    President, InfinityLab Inc.

  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
    Some more info...

    This from our engineering folks..."the temp gauges are not very accurate, recent tests showed them off by up to 30 degrees. Calibration tolerances are +/- 9, so it is possible half the error could be from this. Lastly, the rate of temp rise is important because the time constant for the sensor is about 30 seconds, so if the boiler is rising at 30 degrees/minute, the sensor will lag by up to 15 degrees." I hope this will help you out.
  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    Just a thought.....

    Is the burner still firing as it overshoots or does the boiler coast to overshoot? I find it very common for heavy weight cast iron boilers to overshoot because the heat from the flame is still traveling through the castings after the burner shuts off. This heat continues to raise the boiler water temp.

  • Yes , definitely

    We see that happen with the Weil Mclain Gold 3L oil . We set the high limit of the 4081 to 180 , and it will frequently go 20 , sometimes 30 degrees past that - after the burner shut down at the right temp . I've seen it happen with the Peerless WBV , but not as severe .
  • Bob , can you

    or anyone else recommend a good gauge for boilers ? The Burnham V series and the Weil Gold have recently been
    shipping out with different types than the generic that went bad if you tightened it by hand . I dont remember the brand names of the new ones or the cheapies though .
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