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Help wiring stat to rib relay to control fan on CUH

fedupwithcontrols
fedupwithcontrols Member Posts: 7
in Radiant Heating
Ok, dumb plumber here who hates wiring. I have a Noble combi boiler with a Taco 3 zone relay controller. I’m trying to use heat only Rodgers-White stat to turn on the fan on the CUH and the circulator pump. I bought  a RIBU1C relay to hopefully power up the fan. I also have a 24v knock down transformer somehow that needs to power up the stat too. I have a 5 wire stat line running from stat to CUH where the relay and transformer are. From there to the Taco controller I have another 5 wire running. Does anyone have a dumbed down drawing I can follow? I’m ready to throw stuff. 😂 

Comments

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,210
    edited December 2023
    Is the Taco 3 zone relay controller a pump control or a zone valve control?
    SR503 is a pump control.
    ZVC503 is a zone valve control.
    The wiring is different on each.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Zman
    Zman Member Posts: 7,611
    Where is all this stuff physically located? Is the circ in the boiler room and fan at the CUH? A common way to do this is to wire the circ to the Taco relay and then have the fan run off a strap-on aquastat or snap disk strapped to the supply pipe at the heater. This way the fan never blows cold air. As soon as the pipe heats up the fan turns on...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    MikeAmann
  • GW
    GW Member Posts: 4,817
    edited December 2023
    Fed up it’s cool, you can prolly run circles around us with other things trade related 

    I know that RIB control, and general low-voltage pretty well. I do not have one in my hand, so I cannot cite the colors.

    The RIB has two things going on- 
    the coil
    the relay or contactor 

    I cannot fully understand, you have an air handler? I can’t place what CUH is at the moment

    Does the fan coil have fan center? What terminals make the fan come on? 

    And tell me the purpose of the Taco 


    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,298
    On the RIB

    orange NO, blue NC and yellow (common) are the relay contacts. On the coil white/yellow is common, white/black is 120 volt and white/blue is 24 volt
  • 109A_5
    109A_5 Member Posts: 1,482
    Hello @fedupwithcontrols,
    With the information provided, if the Taco does not control the circulator for the fan unit, I would do it this way.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • JUGHNE
    JUGHNE Member Posts: 11,262
    And any unused wires on the RIB must be taped or capped....and not together.
    109A_5
  • Zman
    Zman Member Posts: 7,611
    @fedupwithcontrols Are you there?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    MikeAmann
  • fedupwithcontrols
    fedupwithcontrols Member Posts: 7
    Sorry for the delay fellas. I’m using the Taco sr-503. Circ is in boiler room. CUH is upstairs. Pic is a drawing of all the components I have in this puzzle. 
  • HVACNUT
    HVACNUT Member Posts: 6,242
    What is a CUH (Central Unit Heater?) and is there a wiring diagram for it? 
    What are B and W for the CUH?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,161
    edited December 2023
    I do no fully understand the CUH. I realize it is an air handler with a blower and a hot water coil. Is there also a coil for cooling?

    Your diagram shows the only wire connections to the CUH is B and W. Is that the only wiring? Is there a place to connect the thermostat, or is it just the B for Hot and W for Neutral to the blower motor?

    If that is the case then you have the incorrect RIB relay. You need RIB2401D (See Below) so you can turn on the blower and the low voltage to the zone control. I believe that RWC is where the thermostat would go for that zone on the Taco 503, but you need to verify that.

    If you do not want the CHU to blow cold air during the time it takes to get the hot boiler water from the basement to the attic, you will also need to purchase a FAN thermostat like the adjustable L6006C from Honeywell or a Snap Disk to place on the return pipe in the attic. This will keep the blower off until the coil is hot.

    https://www.supplyhouse.com/Functional-Devices-RIB2401D-Enclosed-Pilot-Relay-10-Amp-DPDT-w-24-VAC-DC-120-VAC-Coil?_br_psugg_q=rib+relay
    https://www.supplyhouse.com/Resideo-L6006C1018-High-or-Low-Limit-Circulator-Strap-On-Aquastat-65-200-DegreeF-range-5-30-DegreeF-Adj-Differential
    OR
    https://www.supplyhouse.com/White-Rodgers-3F01-130-3-4-Snap-Disc-Fan-Control-Cut-In-130-Degrees-F-Cut-Out-115-Degrees-F

    Here is the diagram, unless the CHU has a wiring diagram that has other components already in there. Also is the CHU also doing cooling?


    Edward Young Retired

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

  • 109A_5
    109A_5 Member Posts: 1,482
    edited December 2023
    Hello @fedupwithcontrols,
    If the Taco SR-503 will be controlling the circulator then this should work. Transformer phasing should be checked. If you don't want to deal with the transformer phasing you would need a DPDT (like RID2401D) type relay to provide an extra set of isolated contacts for the Taco SR-503 control.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,161

    IMPORTANT

    I just thought of something. The CHU may have a 220/240 Volt blower motor, so it is important to connect a 230 VAC input transformer in that case. Check the blower motor rating and measure the voltage with a meter. The 24 VAC transformer MUST have a matching primary (input) voltage for this diagram to work

    Edward Young Retired

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

  • SuperTech
    SuperTech Member Posts: 2,389
    I've been trying to follow this thread and I'm still unclear about what a CUH or CHU is referring to.  A hydro air system?
    HVACNUT
  • 109A_5
    109A_5 Member Posts: 1,482
    edited December 2023
    Hello @SuperTech,
    In this case I suspect it is something like this.
    http://www.2hsc.com/airtex/PDF/CUH_Series.pdf


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • HVACNUT
    HVACNUT Member Posts: 6,242
    109A_5 said:
    Hello @SuperTech, In this case I suspect it is something like this. http://www.2hsc.com/airtex/PDF/CUH_Series.pdf
    Nice, but it doesn't show wiring.
    I think if the OP wants to move forward, he or she can provide the wiring diagram for their particular unit. Or at least a make and model. Throw us a bone, ya know?
  • 109A_5
    109A_5 Member Posts: 1,482
    edited December 2023
    Hello @HVACNUT,
    HVACNUT said:

    Nice, but it doesn't show wiring.
    I think if the OP wants to move forward, he or she can provide the wiring diagram for their particular unit. Or at least a make and model. Throw us a bone, ya know?

    I'm assuming it is just a blower motor B & W (Hot & Neutral). It would be nice if there was a water temperature switch (aquastat) in the cabinet too, but probably not. Yes, more information may help.

    fedupwithcontrols said:

    I also have a 24v knock down transformer somehow that needs to power up the stat too.

    Also no C wire included on the device / wire color / connection terminals note.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • fedupwithcontrols
    fedupwithcontrols Member Posts: 7
    CUH is a cabinet unit heater. 110v fan and a coil. B in hot W is nuetral. Edtheheaterman, I have the aqua stat you mentioned but figured I’d keep it simple for the time being. Your drawing I can follow. Looks like I need to swap out Ribrelays. Thanks. 
    SuperTech
  • fedupwithcontrols
    fedupwithcontrols Member Posts: 7
    On the Aquastat, is that line voltage or low voltage i would wire up? Also someone asked about the heat only stat, it has a R and W terminal. Below is the stat.
    https://www.supplyhouse.com/Robertshaw-RS1100-72-1H-Programmable-Thermostat-w-72F-Max

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