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Need some advice on wiring boiler zone valves

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Steve6662
Steve6662 Member Posts: 6
in Thermostats and Controls

I have a boiler system I'm trying to wire that hasn't been wired correctly for quite some time. I'm a DIY'er but have some experience with HVAC. I have a system with 3 thermostats and 3 zone valves. 2 zones having 8043E1012 4 wire valves, and 1 Taco 3 terminal valve. I'm using a wiring diagram i found on the net that i thought was most similar to what i was trying to accomplish. The boiler has a Honeywell R8285D5001 50VA transformer control center on it. I spent the day wiring this thing only to burn up the transformer when i was finished. I can not figure out how to incorporate the Taco valve in the wiring. All the information i can find talks about running the wires to the TT terminals but my setup doesnt have TT terminals that i can see. So ive ordered another control center and will try again in a few day. Any help on how to wire the Taco valve into this setup would be much appreciated. Thank you!

Comments

  • hot_rod
    hot_rod Member Posts: 27,586
    Maybe consider a zone control relay box to simplify the wiring, especially with some 3 and some 4 wire zone valves.
    The Caleffi ZCR relays have auto resetting thermal links protecting the transformers. No need to worry about frying the transformer.
    Most all boilers have a TT or call for heat connection. What brand and model? Should find a wiring schematic inside the boiler. Or online.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Steve6662
  • Steve6662
    Steve6662 Member Posts: 6
    T
    This is the diagram inside the door of the boiler. Not much information on controls.
  • hot_rod
    hot_rod Member Posts: 27,586
    See where the 24V thermostat (by others) connects. That is the heat call connection. With a relay box it would be the ZC ZR dry contact.
    With zone valves, the end switch connects there.
    The 3 wire zone valve complicates it, check the Taco website, they have a good wiring guide that probably shows the blend of 2 and 3 wire zone valves.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Steve6662
  • Steve6662
    Steve6662 Member Posts: 6
    Yes i see that. I was going to hook my end wires there on Green and Red. But i think the way i wired the 3 wire valve is where is crossed something up and ruined the transformer. I suppose i'll leave it out of the loop for now and get running without the3 wire valve and just open it manually till i figure something out. Thanks for the help!
  • Steve6662
    Steve6662 Member Posts: 6
    I forgot to mention i don't have an external transformer and everything is being run from the transformer on the control center.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,359
    edited December 2020
    Try this


    You can also add a 5 amp fuse to the R terminal then connect all the R terminal wires to the other end of the fuse with a wire nut.

    Two spade connectors and an automotive fuse will do nicely.


    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Steve6662
  • HVACNUT
    HVACNUT Member Posts: 7,483
    @Steve6662, your drawing is 100% correct, but like you said, you dont have TT. Connect the end switches to R and G on the Honeywell control center. 
    Since your using the boilers transformer, break it into 2 steps. Power and end switches. 
    Using a zone panel like @hot_rod mentioned would be the pro way to go. No sloppy wire bundles.
    @EdTheHeaterMan, you have Common from the transformer to the thermostat R's. Will it work as drawn? Yes, but a little confusing for someone who might not know. 
    Steve6662
  • Zman
    Zman Member Posts: 7,614
    The problem you are encountering is that the taco 3 wire is applying power to it's end switch on it's own.
    You will have much less brain damage and will be assured that you do not overload the boiler transformer if you install one of these and wire it as instructed in the manual. You would tie it in to your boiler control where the boiler manual shows "24 volt t-stat by others".
    Your system will be very simple to troubleshoot and look much more professional.
    https://www.supplyhouse.com/Taco-ZVC403-4-3-Zone-Valve-Control-Module-with-Priority
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Steve6662
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,359
    edited December 2020
    HVACNUT said:

    @Steve6662, your drawing is 100% correct, but like you said, you dont have TT. Connect the end switches to R and G on the Honeywell control center. 
    Since your using the boilers transformer, break it into 2 steps. Power and end switches. 
    Using a zone panel like @hot_rod mentioned would be the pro way to go. No sloppy wire bundles.
    @EdTheHeaterMan, you have Common from the transformer to the thermostat R's. Will it work as drawn? Yes, but a little confusing for someone who might not know. 

    I did not select the boiler wiring design. I would usually do it your way but transformer R is in the wrong place to put it on thermostat R. Since transformer R needs to be used on both the end switch and the motor circuits on the zone valve Dah! Terminal 2!

    I also don't recommend spending someone else's money on luxury parts. If it were my customer, I would give a choice of $$$ for labor only to wire this


    or $$$ for a zone control panel for easy service in the future. Then let the consumer decide.


    For cripe's sake, the guy just fried his control center and needed to purchase a new one. The wiring diagram will work and the fuse is less expensive than the ZVC panel. I believe that is all the OP wanted is the wiring design that will work. Has anyone else offered that?

    Electric is color blind. ...and Sharpie makes a marker with a fine point to draw the letter R on the C terminal and the letter C on the R terminal.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Steve6662
    Steve6662 Member Posts: 6
    Thanks everyone for the help. I appreciate you all taking the time to get me on track.
  • Steve6662
    Steve6662 Member Posts: 6
    If i go with the zone valve control module with priority what size wire do you recommend? Is this all wired with just Thermostat wire? Thank you!
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,359
    The Romex or BX wire to supply 120v. to the line-voltage transformers should be at least 14 gauge, but that depends on the circuit breaker feeding the heating circuit. If the breaker is a 20 amp then all the wiring should be 12 gauge.

    The low voltage wires should be 18 gauge minimum. Sometimes installers use 20 gauge and smaller. Not a good idea, especially when there are larger (40VA and up) transformers involved. I like to use 18-5 conductor wire on zone valves. You never know when you might need an extra conductor in the future.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • clammy
    clammy Member Posts: 3,256
    As other have stated save time and headaches and get a taco zone valve controller and your done . Any future service that will be required will be much easier for all concerned . There’s nothing worse then going to a service call and having to deal w some birds nest of wires no body wants to start in messing w that mess when usually u end up straighten it all out because of a bad wire nut or usually ends up being some thing stupid . Do yourself a favor and make life easy . I ve seen people waste hours screwing w zone valve wiring messes and still leaving a mess and shorting controls and transformers out . Take the advice or hire a pro peace and good luck clammy

    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating

  • Crispy
    Crispy Member Posts: 25
    edited May 2

    This post helped me so much! Thanks @EdTheHeaterMan for your reply with the creative picture edit and explanation. Doing this work for a friend, I inherited a 1995 Burnham boiler in a 1950’s remod that had two zone valves mechanically held open with the lever, one circulator loop for a copper-in-concrete floor heat slab and the wiring jumbled to run the boiler constantly on the aquastat. No thermostats. The house was empty and had frozen after an apparent boiler failure. I had never worked with zone valves before this job. After getting through the below-zero weather, I stripped out all the wiring, added two more zone valves and began the re-wire job. The boiler had a Honeywell R8285D control center and there was a Taco SR503 3 zone relay panel.
    I now have one t-stat talking to the slab zone valve and its circulator via the Taco panel TT connection and the end-switch on the zone valve. The other three t-stats talk to their zone valves and use the end switches at TT to fire a different circulator on a big primary loop.

    I would like to add one thing that was a problem which I figured out pretty quickly, luckily. I had to swap the leads on the TT connection for polarity at TT on the Taco panel. After switching the 24V hot and common at TT, the Taco panel fired on command from the end switches.
    I still have to fill the system and do a real test but I’m thrilled to have the control wiring behind me without buying a thing.

    I hope this helps someone else forge ahead through their mess and salvage everything for no $. Thanks again EdTheHeaterMan, C

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