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Indirect water heater wiring.

I currently have a Burnham AL53A indirect water heater that is leaking and I would like to replace it. I am considering a Burnham AL50SL but as I look at the wiring, the TPI calls for 24v power but I don't know where to get that from. The current setup has a single thermostat wire from the water tank Aquastat that goes to a Honeywell YHR845A switching relay that runs the Taco circulator. The new water heater calls for a Circ/TT hookup as well as the 24v hookup. Should I connect the TPI TT to the YHR845A as it is now and run another line from a nearby 24v transformer to the 24v connection on the TPI. Thanks Eric

Comments

  • Ironman
    Ironman Member Posts: 6,597
    The electronic aquastat needs 24v to power its logic. Anywhere you can pick up power from will work.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • ekd4176
    ekd4176 Member Posts: 2
    Thank you very much
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,414
    There is no access to the common (C) on the Honeywell YHR845A. You will need to look elsewhere for 24V or go under the printed circuit board to find the C side of the transformer to solder to, but that will void the warranty and the protection of the UL listing of that control.
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • JohnNY
    JohnNY Member Posts: 2,761
    I really dislike this absurd trend of having to power a controller on something as simple as an indirect water heater.
    Contact John "JohnNY" Cataneo, Master Plumber
    in New York
    in New Jersey
    for Consulting Work
    or take his class.
    Solid_Fuel_ManHVACNUT
  • Nikos10
    Nikos10 Member Posts: 2
    edited December 2020
    Hi think i'm have same/similar issue...bought new indirect hot water heater yesterday (last unit was 20 years old).

    Connected thermostat to taco sr501 (no wiring change in taco). Taco control makes buzzing sound and zone is always open calling for heat.

    Will not start circulator or fire boiler but red light is on and it buzzes like a street light at night. Never did before with old unit.

    New thermostat mentions 24v, I see that in the taco box as well but don't know what to do.

    I have hot water to heater. I get it by shutting unit kill switch when heater actually needs hot water but once up to temp the zone never shuts off (light) but pump and boiler are off and taco zone buzzes slightly. Can hear when you get close.

    Has to be mis wired. I don't understand the 24v but see those markings on the thermostat and taco control. I'm assuming I have to do something there but don't know what.

    Looking for advice. Thanks so much...

  • Zman
    Zman Member Posts: 7,005
    What brand heater is that? Do you have the instructions?
    It looks like the old wires should be on the other 2 terminals on the left. The terminals on the bottom should be connected to R and C on the Taco to bring power to the controller.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 10,363
    Anything to make it more complicated and more expensive
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,307
    I think it's done @JohnNY for the flash-bang led display. People get all hopped up if there are cool digital numbers to look at. 

    I completly agree with your sentiment. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • JohnNY
    JohnNY Member Posts: 2,761

    I think it's done @JohnNY for the flash-bang led display. People get all hopped up if there are cool digital numbers to look at. 

    I completly agree with your sentiment. 

    Nothing like making things far more complicated than they need to be.

    Contact John "JohnNY" Cataneo, Master Plumber
    in New York
    in New Jersey
    for Consulting Work
    or take his class.
    Solid_Fuel_Man
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,414
    edited December 2020
    @ekd4176 You will need to provide a seperate 24V transformer to provide power to operate the electronic control. This is your diagram


    @Nikos10 Yours is easier. This is your wiring diagram.


    Three conductor wire from the water heater thermostat to the switching relay. You need a jumper wire to connect the red wire from R on the Taco SR relay on 2 terminals of the water tank thermostat

    A third wire (green) for the common or return path to operate the LED and onboard microprocessor of the water heater thermostat.

    Merry Christmas
    Ed


    BTW electric is colorblind... you don't need to use green if your 3 conductor wire has a different color
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
    ZmanSolid_Fuel_Man