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Taco fuelmizer

Taco fuelmizer

Looking for some help from taco fuelmizer users. I’ve noticed in all the videos posted to YouTube and pictures taco has on their website that the adjustment knob for the reset ratio is black but the one I recently purchased doesn’t appear to have the same potentiometer. I feel that the pot meter in mine might be backwards, is anyone able to see the numbers on the side of the potentiometer and send them to me and maybe a picture? I’d like to compare the data sheets of the different pot meters taco used the their production run.


  • Larry Weingarten
    Larry Weingarten Member Posts: 2,782
    Hello, This isn't my field of know-how, but your post was about to fall off the page unanswered, so... Have you contacted Taco to get their input? My experience is that they like being helpful. o:)

    Yours, Larry
  • Dave H_2
    Dave H_2 Member Posts: 519

    We do use different manufacturers for little components and the look on the inside might be different.

    it should read from left to right;
    OFF, -30, -20, -10, 0 (at the top), 10. 20, 30, 40

    What are you experiencing? what issues do you see? where are you located?

    Dave H.
    Dave H
  • getheheat
    getheheat Member Posts: 3
    Thank you Larry and Dave, I was starting to think this was a lost cause.

    The issue I have is the same as https://forum.heatinghelp.com/discussion/144060/taco-fuel-mizer

    It seems the colder "more negative or closer to off" I set the design temperature the hotter the supply water becomes, looking at the chart in the manual the higher the design temp the steeper the ratio, this seems to be the opposite of what is happening.

    The printing on the PCB is as you described and I have a question about the "off". Does off mean that the ratio is set to off so as long as there is a call from TT the controller holds XX closed or does "off" mean the controller holds XX open even if a call for heat on TT is present? I ask this because if I turn the adjustment to "off" the boiler still runs.

    I live in central PA and used 0° as outdoor design temp with the radiators sized to provide enough heat at about 155°supply temp. However I am in the process of changing the house from forced air to hot water, the house is not insulated but when I did the heat loss I calculated it with insulation because after I'm done installing the heating I can then insulate but in the mean time to have adequate heat I also did a heat loss calculation for the current conditions not having insulation and found I would need 190° supply water at a 0° day. So if I understand this correctly with the current conditions of the structure and looking at the chart if I set the adjustment at 10° that should make the supply water approximately 200° on a day the outside temp is 0° but the adjustment seems backwards and in order to raise the supply water temp I had to turn the adjustment to -10°

  • Dave H_2
    Dave H_2 Member Posts: 519
    Ok @getheheat ,

    I did some digging since the previous post was eight years ago and I didn't recognize my own writing !!!!!

    We did have a handful get out with the pot adjustments opposite of what we designed. It was hard to find then since most were installed in areas where 0F was the design.

    Anyway, rather that remove what you have, the dial will now operate from left to right as follows:
    40, 30, 20, 10, 0 (at the top), -10, -20, -30, OFF

    What OFF does is take the unit out of the outdoor reset curve and will operate on the boilers controller and the Fuelmizer will at this point only be a switching relay.

    Dave H.
    Dave H
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 4,946
    Holy Moly! I thought I was crazy but I found one of these several years ago, and just made the assumption that I was thinking "Left Handed" (That is what my son calls it)
    I am somewhat Dyslexic and transpose numbers often. So I just set it backwards and left it alone.

    Wait until I tell all the folks at the DNA (National Dyslexia Assoc,)

    Edward Young Retired HVAC Contractor & HYDRONICIAN Services first oil burner at age 16 P/T trainer for EH-CC.org