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Tstat and vent damper wiring

PrecaudPrecaud Member Posts: 341
edited October 10 in Strictly Steam
I'm about to install a GVD-6 vent damper and new thermostat in my steam system, and thought I should get some input about how best to hook then up. The old tstat only had battery power, while this one (Honeywell TH5110D) can use either batteries or the 24VAC. Here's a diagram of how things are wired now.



As you guys probably know, with AC coming out of a transformer, there is no defined "Ground" or "Common", it can be either side. So how it's wired probably decides which is which.

1. My guess is, the red wire out of the xfmr is the most likely "common", yes?
2. So, if I want to avoid using batteries to power the tstat, then the red wire gets connected to the C terminal (common) on the tstat, yes? (This is pretty obviously so but I'll ask it anyway)
3. What's the best way to hook the vent damper relay into the system? Insert it anywhere in the series daisy chain? Or outside the loop?

TIA for your input.
1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.

Comments

  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,315
    I would think red would be hot but it probably doesn't matter. Based on the colors and polarity above yes C on the stat would be the red wire.

    Does the vent damper have a proving switch? Two wires to drive the damper and two wires to interlock the burner circuit?
  • EdTheHeaterManEdTheHeaterMan Member Posts: 802
    edited October 10
    So to start with Electric is colorblind.
    We assign colors to help us determine what wire is at the other end of a long run of wire.

    We (the Pros in the industry) like to see a C on the transformer as common and an R on a transformer as the starting point of the power The starting point on your diagram is labeled "WHT" and goes directly to the thermostat "YEL". The important question at the thermostat is the terminal designation on the thermostat.

    Is "YEL" connected to the terminal designated as W or R on the thermostat? This is more important than you might think.

    If your transformer does not have C and R terminals then it has colored wires. (if the wire has a stripe in it, that is Common) and R is the starting point or "POWER". A complete circuit goes from POWER to a LOAD and back to the source at COMMON.

    The next point is that we prefer all the Safety and Limiting devices are in series before the device that operates the main burner (or gas valve).

    There is a reason for this that I remember learning about years ago, I just forget what the reason was at this time (AGE DOES THAT YOU KNOW) .

    So your diagram is somewhat flawed, but that does not mean it is not safe or that it won't work. It just means that adding the damper will be more difficult to figure out.
  • JUGHNEJUGHNE Member Posts: 7,195
    Can you easily change the cable to the t-stat?
  • PrecaudPrecaud Member Posts: 341
    edited October 10
    @EBEBRATT-Ed Yeah, the convention is Red = Hot, but we can just take the colors as identifiers it this case. Yes, the damper will have two wires to power it, a 3rd for the call-for-heat, and the fourth the proving switch.

    @EdTheHeaterMan , yes yellow is connected to R on the tstat, and black is to W.

    I know the existing wiring scheme works - it has worked for decades with two different tstats. But if there's a better or safer ordering, pls tell. Rewiring is not a big deal.

    If I understand you correctly, you would swap the LWCO and gas valve positions in the diagram, yes? Or just get the gas valve at the bottom of the tree?
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
  • PrecaudPrecaud Member Posts: 341
    JUGHNE said:

    Can you easily change the cable to the t-stat?

    ? Por qua ?
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
  • EdTheHeaterManEdTheHeaterMan Member Posts: 802
    edited October 10
    Try this
    The labels on your gas valve are reversed. see the Red from the Damber should go the TH or R on the gas valve and the Wht on your gas valve should be TR or Common

    I have moved the thermostat to the R side of the transformer and connected transformer R to thermostat R.

    It makes more sense for someone unfamiliar to better understand later (years from now).

    Thermostat W now feed power thru all the limits and safety devices to power up the damper (check your damper wiring to see if it conforms to the diagram)

    Bl or Blue wire to the damper gets a 24V signal in order to open. The Bk or Black wire is powered with 24 V all the time.

    The W or White wire is common for the damper to have a return circuit to close the damper after power from Bl is turned off by thermostat or limit.

    The R or Red wire is connected to the safety switch in the damper so the burner won't operate unless the damper is fully open.
    Precaud
  • EdTheHeaterManEdTheHeaterMan Member Posts: 802
    IMPORTANT Note that the Molex plug changes colors from one side to the other.

    If you decide to wire the system without the Molex plug please adjust the wire colors accordingly.
  • PrecaudPrecaud Member Posts: 341
    edited October 10
    Thanks much, @EdTheHeaterMan . Great cut-and-paste job, BTW! I haven't received the damper yet, it is due to arrive Monday. But I think I can change the wiring to what you suggest relatively painlessly; all connections are easily acccessible. I'll be making my own harness for the damper, so whatever the color scheme ends up as, I will definitely be leaving a wiring diagram for a future owner to refer to.

    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
  • EdTheHeaterManEdTheHeaterMan Member Posts: 802
    if it comes with both ends of the Molex plug, I would use them to make repair/replacement easy. If it does not. then double check the wiring instructions that come with the damper. If it is a replacement part for some other boiler, it may not have both ends.
  • PrecaudPrecaud Member Posts: 341
    It's a standard GVD-6 from Field w/o harness, I don't think they supply a plug with it. But we'll see shortly. It is no doubt a standard Molex plug that I can order from Digikey or similar. I already have a good selection of their connector inserts and crimping tool.
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
  • motoguy128motoguy128 Member Posts: 182
    Another option is to take the opportunity to upgrade the boiler to spark ignition and use a standard Honeywell Control that already has the plug on the board. Or upgrade your controller and keep the other as an emergency spare if it’s already DSI But older controller. The damper can be powered open and parked if needed. NEVER open the damper manually.

    Depending on flame sense setup... but here’s a few

    https://www.supplyhouse.com/ICM-Controls-ICM290A-Universal-Intermittent-Pilot-Gas-Ignition-Control

    https://www.supplyhouse.com/Honeywell-S8610U3009-Intermittent-Pilot-Control-4584000-p

    And the full kit
    https://www.supplyhouse.com/Honeywell-Y8610U4001-Intermittent-Pilot-Control-Conversion-Kit
  • PrecaudPrecaud Member Posts: 341
    For those who prefer to make their own wiring harness to a GVD damper, the connector for the cable end is a Molex 150179-2040, available at Digikey or Mouser for 43 cents ea.
    https://www.mouser.com/ProductDetail/Molex/150179-2040?qs=/ha2pyFaduhf66pxh2jZEZt12ojzqnleL8NHbpwBl2nfcph1hY56Yw==

    You'll also need four of the 150181-1016 female pin connectors at 10 cents each:
    https://www.mouser.com/ProductDetail/Molex/150181-1016?qs=OAhjpuo3Vu730aRyQweZFg==
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
    ethicalpaul
  • EdTheHeaterManEdTheHeaterMan Member Posts: 802
    edited October 14
  • PrecaudPrecaud Member Posts: 341
    There is no connector on the boiler end of my ol' Bryant...
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
    ethicalpaul
  • EdTheHeaterManEdTheHeaterMan Member Posts: 802
    edited October 14
    there must be a boiler end. You certainly can't put both ends of the wire on the damper???

    Should I call it the "heater end" or the "system end" whatever end you want to call it. (let's just call it the other end) The standard extension cord that connects the damper to the heater has a 4 pin on one side (Damper side) and a 6 pin on the other end. This is evident in the diagram that comes with the damper instructions... That is why I mentioned that electric is colorblind and you should adapt wire colors from my diagram to your system accordingly.

    It is now obvious to me that the connecting cord did not come with the damper. This will make connecting the wiring somewhat difficult. Probably should have ordered the connecting cord with the damper. Getting the 4 pin connector is a good idea.

    here is one already made
    https://www.supplyhouse.com/Hydrolevel-45-353-Wire-Harness-for-Connecting-Safgard-1100-and-1100M-to-Vent-Damper-Plug-On-Boiler-Control-Modules?gclid=CjwKCAjww5r8BRB6EiwArcckC9XS6Ca7rnYDUwHmBjxigc_GiMUQCjkGz8C9Goed3nzPJvM-M5wXOBoCU3gQAvD_BwE
  • PrecaudPrecaud Member Posts: 341
    Dear Sir @EdTheHeaterMan , no worries, I work with electronics every day and hooking this thing up will be one of the simpler jobs I'll do all year.
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
    EdTheHeaterMan
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