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Taco SR501-4 Switching Relay / Honeywell RA832A Switching Relay

I have a 4 zone hot water boiler heating system. The t-stats are all connected to individual Honeywell Type RA832A switching relays which activate individual circulators without any circuitry to an aquastat.. I understand this installation was used by many technicians in older systems. I replaced one Honeywell RA832A switching relay because I tested the output of the transformer and found it wasn't putting out any voltage to the t-stat. After replacing the Honeywell RA832A with a Taco SR501-4 switching relay per Taco's wiring diagram. The circulator does come on, but stays on and never shuts off. I disconnected the zones t-stat and the circulator still continues to run. What didn't I do correctly? Please help!!



  • JohnNY
    JohnNY Member Posts: 2,972
    You've got it like this?:
    Contact John "JohnNY" Cataneo, Master Plumber for Consulting Work
    Or for plumbing in NYC or in NJ.

    Or take his class.
  • Eric_32
    Eric_32 Member Posts: 267
    edited December 2015
    On the 832A there is jumpers in place to power the pump. #1 and #2 are power and neutral into the 832A. There is a jumper from #1 to #3, so there is always 120-volts sitting there at those terminals. #4 terminal is hot to the pump. It gets voltage from #3 when the T T terminals touch together.

    On the Taco box there is a couple ways to wire it depending on your boiler. If it's a cold start or tankless coil. Cold start means the boiler will never run unless there is a call to from a thermostat. Tainless coil will maintain a certain temp at all times to make hot water.

    I'm guessing you have a tankless oil fired boiler? Since your 832A never had a wire to tell the boiler when it had to run. I'm guessing you have a Lo Limit control in the boiler aquastat that did.

    In that case the circulator should get power from from the ZR and ZC terminals in the boiler aquastat box. They are used when adding zones to a tankless coil boiler. What they do is shut off the pump if the boiler water temp drops too low so you can continue to have hot water for the tankless. Terminal 6 N/O is your hot to the pump and #5 is power from ZC. The neutral to the pump ties in with the neutral at the N terminal. Terminal 4 N/O goes back to the boiler to tell it the zone is calling.

    Taco wiring manual:

    Honeywell 832 manual:

  • pipor
    pipor Member Posts: 2
    Thank you for your reply. I pretty much understand what you're saying. I just want to be sure of a few things you said after viewing the wiring diagrams. Looking at the diagram for Typical wiring of the Taco switching relay. It shows N/O #6 and COM #5 going to the TT on the boiler aquastat box. If I wired it this way should it work correctly?. Or do you recommend I use your wiring procedure? Which is the Alternative wiring diagram less the 120 vac power to terminal H and N on the Taco relay? Another words, Am I receiving 120 vac only from the Aquastat ZC and not from another 120 vac as the alternative diagram is showing 120 vac to the H and N input terminals? Hope you understand me..
  • Joe Mattiello
    Joe Mattiello Member Posts: 638
    Good morning
    Couple of things we need to clear up, is this tankless boiler application? Traditional Tankless boiler is usually equipped with a triple aquastat L8124 with a low limit. Using the Taco alternative wiring diagram will enable the boiler burner directly through ZR terminal, and ZC will be energized with 120 volts to pull in the relays on the Taco control when the 8124 min temperature is satisfied.
    A lot of people confuse wall hung tankless boilers with traditional tankless boiler and think the alternative wiring schematic is correct; that’s why I want to clear up any ambiguity.
    If you’re using standard wiring, hot leg of the circulator should be installed on the N/O terminal, and neutral should be wired to any neutral; leave the factory installed jumper in place. If you have the wiring correct, when R, W terminals at the top of the control close the circulator will run, and when R, W open the circulator will stop.
    If you relay is not functioning per design, and how I mentioned, please call me at 401-942-8000 to discuss what might be wrong with your wiring. Hopefully this was helpful
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • amheroes
    amheroes Member Posts: 1
    I have a honeywell RA832A relay and not sure how to wire it...there is currently no relay in place! The pump is wired direct and runs nonstop. I believe numbers 1 & 2 are for power to relay. #4 is hot to pump and I would assume #3 is line to pump but circuits with #1?? Also have two T and two X hookups...I'm lost!!
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,785
    Why are you touching it in the first place? What problem are you having? Isnt there a wiring diagram right on the cover?
    Tell us a little more about your heating system, the controls on the boiler, zones, what's on the t's and whats on the x's and where they are wired.