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Honeywell Vision pro wifi and Taco SR502 weirdness

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jumbee
jumbee Member Posts: 25
in THE MAIN WALL
I have a 2 zone hot water system with 2 stats. I purchased a TH8321 wifi to replace the stat in zone 1. I connected the wifi stat with a c wire from a separate transformer to zone 1. Then this is where it gets weird. Wifi stat works but with zone 2. So I switch the tstat wires on the Taco i.e. I connect the wifi stat to zone 2. It works with zone 2 but zone 1 doesn't work with the old stat. It seems that with the wifi stat connected only one zone will work.
So I remove the wifi stat and reconnect the old stats. Everything works as it should.
Can anyone help with this weirdness?
Thanks

Comments

  • ratio
    ratio Member Posts: 3,631
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    Separate transformer? Power the 8321 on the RC & C terminals, remove the jumper between RC & RH, use RH & W1 for the call to the Taco.
  • jumbee
    jumbee Member Posts: 25
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    That's the setup for the 8321. Jumper between Rc and R removed. Power for 8321 is C and RC. Call to Taco is W and R. The system works correctly with the old stats. Once I connect the 8321 then weirdness. I'm wondering if it is has something to do with the Zone priority?
  • Eric_32
    Eric_32 Member Posts: 267
    edited October 2016
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    This is a wiring schematic I received from Taco regarding some wifi tstats. Eugene from Taco said some draw too much power from the Taco box to allow the relay in the box to pull in. A 2nd external transformer has to be added. I hope the attachment opens...
  • ratio
    ratio Member Posts: 3,631
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    Oh yah, I thought you indicated that you have an additional separate xfrmr. Those WiFi radios are power hogs, if you're trying to power it from the Taco you'll run into issues, like only the first circuit that calls will be able to activate.
  • jumbee
    jumbee Member Posts: 25
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    Ratio:
    Yes I do have a separate transformer powering the 8321 connected to C and unjumpered RC. And that's what's still happening. So looking at the schematic isn't that how mine is connected or am I missing something.
  • ratio
    ratio Member Posts: 3,631
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    Hmmmm. TH8321WIFI, with 24vac xfrmr connected to RC & C, RH-RC jumper removed, RH connected to SR502 zone 1 R, W connected to SR502 zone 1 W. With this configuration, when the TH8321WIFI calls for heat, the zone 2 pump runs? Does this match the SR502 relay panel? The schematic that @Eric posted above shows a jumper from the xfrmr R to the SR50x R, but I'd be leery of doing that without a better understanding of how the SR502 is powered.

    What kind of stats are the existing ones? If you jump the stat terminals R-W one zone at a time, what happens? Do you have a voltmeter or a clamp-on ammeter?

  • jumbee
    jumbee Member Posts: 25
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    The existing stats are old battery powered honeywells. I have R connected to zone 1 terminal "T" and W connected to zone 1 terminal "T". I do have a voltmeter. I'll try jumpering stat terminals R-W when I get home. I'll also test the Taco terminals "T" to see which one is common and which one has 24v.
  • jumbee
    jumbee Member Posts: 25
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    Ratio:
    The SR502 doesn't have terminals R and W. It has terminals T and T. See attached pic
  • GW
    GW Member Posts: 4,693
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    I quickly scanned the thread, unless I'm mistaken don't you need a relay? That's what I have done in the past
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • jumbee
    jumbee Member Posts: 25
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    GW:
    A relay where? On the SR502?
  • hvacfreak2
    hvacfreak2 Member Posts: 500
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    With the RH-RC Jumper removed there should be no need for a relay.

    However , I have been bit by this too many times. If you reinstall the jumper at the stat and energize a relay and connecting TT on the normally open contact arrangement I bet you find that it works like it should. Common ( neutral ) from the relay coil goes to the source that is powering the stat.

    As to .." why " , I don't know.
    hvacfreak

    Mechanical Enthusiast

    Burnham MST 396 , 60 oz gauge , Tigerloop , Firomatic Check Valve , Mcdonnell Miller 67 lwco , Danfoss RA2k TRV's

    Easyio FG20 Controller

  • ratio
    ratio Member Posts: 3,631
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    Shouldn't. The TH8321 has two R terminals, one for the heat side & one for the cooling side. They come with a jumper installed, & take their power from the cooling side. Without the jumper, the W terminal should be completely isolated from the power xfrmr.

    I don't know what's going on, and it's bugging the you-know-what outta me!

  • GW
    GW Member Posts: 4,693
    edited October 2016
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    Ok yes, if it works with jump removed that's great. I've done this once only, single zone wall hung with no zone board.
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • jumbee
    jumbee Member Posts: 25
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    Issue resolved. Previous owner/ installer wired 2nd floor pump as zone 1. So I connected TH8321 to zone 2 "TT" which actually controls the zone 2 pump ie first floor heat. So all's well. Thanks to everyone for your help.
  • ratio
    ratio Member Posts: 3,631
    edited November 2016
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    Thanks for the follow-up. Glad you figured it out, those kind of things can be real head-scratchers!

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