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Electric boiler operation

Bob Larson_3
Bob Larson_3 Member Posts: 13
edited November 2020 in THE MAIN WALL

I'm working on a 60 year old New York electric boiler. I replaced the aquastat relay, and it's working again. But when I started it up, only one element came on. It's heating slowly, but I can't for the life of me figure out how the elements are sequenced? It's just controlled by the 24v control circuit in the relay as far as I can tell. Is there another control that I'm missing? I'm concerned that when the weather turns colder, one element won't keep up. I have continuity thru all 4.

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    Is there a wiring diagram?   

    Or a model number that we could use to find a wiring diagram?
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Bob Larson_3
    Bob Larson_3 Member Posts: 13
    Here's the info
  • Bob Larson_3
    Bob Larson_3 Member Posts: 13
    The wiring diagram on the boiler only showed the 24v control circuit and nothing else. But I didn't take a pic of it.
  • Zman
    Zman Member Posts: 7,561
    Some sharper pictures would help.
    Did you check voltage or amperage?
    Did you Ohm the coils or just check continuity.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Bob Larson_3
    Bob Larson_3 Member Posts: 13
    Voltage was fine. Ohms were around 15 if I remember correctly.
  • hot_rod
    hot_rod Member Posts: 22,021
    Loops a lot like the EFM boilers, maybe a private label. Should have a step or time delay control.
    https://cdn.efmheating.com/eb4-Manual-Orig.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    Looking at @hot_rod 's post and other brands of electric boiler, they all seem to have the same components and your second stage of heating elements should come on by way of a 2 pole contactor connected to a time delay relay or a sequencer. So you either have a bad time delay if the contactor is not pulling-in or you have a bad contactor if the contactor is not pulling in or if it is pulling in and the elements are not energized.

    If we could see the areas indicated on the picture it would be helpful




    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Bob Larson_3
    Bob Larson_3 Member Posts: 13
    Thanks, Ed. I haven't been back to that job since Saturday. She says it's working fine. I'm just concerned that may change when the weather gets colder. It may be that there's no problem.
  • Bob Larson_3
    Bob Larson_3 Member Posts: 13
    So I went back today and the sequencer has been fried. Is this something that they even make any more?


  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Looks like the micro switch can be replaced. 

    Im not familiar with the sequential operation of the 4 elements. 

    Looks like there are only 3 connected. You could replace the sequencer with two contractors, and a time delay relay. Or if you have an extra conductor to the thermostat or can pull a new thermostat wire. Install a 2 stage thermostat to operate the two pole contactors.

    Stage 1 would be 2 elements, and stage 2 would be the additional 2 elements (all 4 energized). 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    You may not be able to get an exact fit. You can make it work with aftermarket parts. You need to know how the electric parts work to do it. Not an easy thing to do unless you are experienced in this type of thing.

    You knew enough to realize that not all the elements are powered. Take a look at the diagram Hot Rod Bob Rhor sent you and compare it to your diagram. There is a time delay for the second set of contacts. Maybe you could eliminate the defective sequencer and replace it with a contactor and a time delay available from any HVAC supply company.

    The section on your diagram (Part 36E5) that is bad could be replaced by 2 contactors and 1 time-delay relay.

    https://www.supplyhouse.com/Packard-C230A-2-Pole-Contactor-24V-30-Amp

    https://www.supplyhouse.com/MARS-32391-Adjustable-Delay-on-Make-Time-Delay



    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • hot_rod
    hot_rod Member Posts: 22,021
    pretty sure parts are still available for that or a very similar boiler. EFM = Electric Furnace man
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Bob Larson_3
    Bob Larson_3 Member Posts: 13
    Thanks everyone for your assistance! I will be able to give them options.