Please and sorry -- a Thermostat question -- Home Heat

Discussion in 'Fred's House of Pancakes' started by cyberpriusII, Feb 10, 2021.

  1. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Trying to avoid drama, but have a major "probably" to be death in close family member from CoVid -- my family and I have not been exposed, but, well....you can guess, lots of dark moments.

    In the meantime, home thermostat has died. Buttons are stuck, but if you really spend a lot time, you can EVENTUALLY get the setting to move. But, I mean a lot of time, and the setting moves in fits and starts. From 65 to 72 all at once.

    upload_2021-2-10_16-16-33.jpeg
    The above is obsolete. The replacement looks nothing like the above -- but it is the "called upon replacement in the catalog." The old thermostat has "White, yellow, green, red" wires. The new thermostat has slots for those, but has a "jumper" between red and "red C".

    The old thermostat has no "red C" and no jumper. The system is 24v.

    I think if I just remove the jumper (and it says to remove it in the manual if you don't need it), all will work.

    So, If I remove the jumper, hook it all up and restore power, if it all works, all is good. If it does not work, replace the jumper?

    Is this a safe way to go about it? No sparks, explosions, visits from dead Vikings?
     
  2. San_Carlos_Jeff

    San_Carlos_Jeff Active Member

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    It's all low voltage stuff. Remove the jumper and give it a try.
     
  3. ChapmanF

    ChapmanF Senior Member

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    Do you have both heat and A/C being controlled by the original thermostat?

    If so, it is being supplied on red, and it is using white to ask for heat, yellow to ask for cooling, and green to ask for just fan (assuming the wiring was done by someone who believes in norms).

    The replacement is built to allow for the possibility that you could have a heating system and an A/C system supplied by different transformers, so the red from your heating system would go to 'red' and the separate red from the A/C system would go to 'red C'. If you have heat and A/C but they are just sharing one red, then you keep the jumper; removing it wouldn't hurt anything, only the A/C won't turn on.

    If you turn the heating system off by its switch or fuse or circuit breaker, no Vikings should appear while you are fiddling with thermostat wires.

    I've seen some cheaper electronic thermostats (they are itty bitty computers, after all) just get sort of randomly wedged, and be fine again after cycling the power to them. Did you try that?

    Red C was a Detroit-area band back when, and launched Susan Calloway. I was there when you could hear them for free on the sidewalk in front of Gayle's Chocolates.

    How weird is this? Seems to be an unrelated band "Red C" in the DC area, and another Gayle's Chocolates in Arizona. Hmm, no, wait, same Gayle. Lucky Arizona.
     
    #3 ChapmanF, Feb 10, 2021
    Last edited: Feb 10, 2021
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  4. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Natural gas system. One big "fan thingy" outside. Heat and cool. Never use the cool part of the system. The front of the thermostat pulls off the wall with just a gentle pull, leaving behind a wall plate with all the wires attached. The top part just pushes back into the plate.

    I have pulled off the front part several times and banged, cursed and threatened it, but nothing seems to shake loose the buttons. When I put it back on and turn the breakers back on, still stuck.

    Big snow storm supposed to hit later tonight. So, I suppose I will put back the top and try to get it set to keep us somewhat comfortable -- as long as I can get it to 63 F or so, we will be O.K.

    This was installed by an HVAC guy around 2009.
    Kris
     
  5. Trollbait

    Trollbait It's a D&D thing

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    The conduction markers on the back of the buttons wears off, assuming these are the rubber type, so the button no longer completes the circuit when pushed. There are kits for fixing it, if you want to bother pulling it apart. You can even DIY fix with an old device with working buttons and silicone glue.
     
  6. ChapmanF

    ChapmanF Senior Member

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    By the way, there shouldn't be much need to obsess about the "called upon replacement in the catalog." The local friendly hardware store or big box store probably has half a dozen thermostat models that would work ok, and get you out of the business of cursing and threatening this old one while waiting for a particular blessed replacement.

    On the other hand, I just noticed yours is a Honeywell. Those are respected; the cheapie ones that I've experienced needing reboots weren't Honeywells.

    From your description, I wouldn't necessarily suspect there's anything more wrong with it than a cotton swab and some alcohol on the contact pads under its rubber buttons wouldn't fix. Might be worth a try.

    Edit 1: or maybe Trollbait's got it, and it's not just oxidation, but something worn away. I wonder if the back of the button could be painted with some of this conductive paint I've got left over from the two times I ever repaired a rear window defogger.

    Edit 2: if the "called upon replacement" is another Honeywell, though different in appearance, and chance it will snap on to the same backing plate already wired up for the old one?
     
    #6 ChapmanF, Feb 10, 2021
    Last edited: Feb 10, 2021
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  7. Trollbait

    Trollbait It's a D&D thing

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    Will the paint stick to a silicone based rubber? The tricky part of a DIY transplant of a good button back is a glue that works. I have extended to life of TV remotes doing so.

    With rubbing alcohol likely in the house, or perhaps an electronic cleaner, might as well try. Only real cost is time.
     
  8. John321

    John321 Senior Member

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  9. kenmce

    kenmce High Voltage Member

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    With a Honeywell you'll hardly ever get vikings. You only really see them with J√łtul and Buderus systems.

    The outside bit is a heat exchanger. When you need heat it pulls some out of the air and sends it into the house.
     
    #9 kenmce, Feb 11, 2021
    Last edited: Feb 11, 2021
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  10. ChapmanF

    ChapmanF Senior Member

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    Not all of us live the dream of having a heat pump. Some of us still just have a box making gas flames inside for heat, and a big fan thingy outside used only for cooling.
     
  11. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Some thermostats seem unique to the maker. Carrier Infinity was my brand. 12 years old when failed and company who installed it could suggest no replacement the thermostat. Web-mailed Carrier who said they couldn't either. eBay. A new in box one $850. Bought one used $250.

    Will replace whole system next time it goes.
     
  12. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    A fairly clear 'redneck' version of thermostat wiring:
     
  13. jdenenberg

    jdenenberg EE Professor

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    My home has a 45 year old "Trol-A-Temp" (bought out by Honeywell decades ago) 3 zone forced air heating system with central AC. Some of the thermostats were starting to stick off, so I bought Ecobees (skipped a few generations of technology).

    Ecobee support told me that they were not compatible, but after some head scratching and running multiconductor cabling through the walls (the original wiring only had 3 wires - they turned out to be Rh, Rc and a shared W/Y wire), I was able to run full-time R and C up to the new thermostat and connect both the W and Y wires together at the zone controller to get the system working. The old rotating knob in the basement still selected Heat or cool and the Fan was controlled by the plenum switch for heat and directly turned on whenever the AC was running (Not controlled by the Ecobees). I guess my many years of EE education paid off,

    JeffD
     
  14. ChapmanF

    ChapmanF Senior Member

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    Honeywell has been a pretty dependable brand for basic thermostats that won't be tied to any one specific brand of heating system.

    When I replaced my heating system, I considered the special thermostat from the manufacturer (I think it was $400-ish), but eventually opted for a Honeywell because it would be more flexible and not tied to one specific brand.

    There can be some other considerations that make the specialized thermostats more attractive. The video above showed thermostat wiring with a C (common) wire, allowing the thermostat itself to be powered, so it can have fancy electronic features. That's obviously a nice thing these days. But what do you do if you have an older house that only has 4-wire thermostat wire run in the wall, so there's no common available?

    As mentioned in the video, some very simple electronic thermostats (like Kris's, maybe) are able to steal all the power they need from the control circuits without actually triggering the heat to come on. Or you can use an electronic thermostat that just gets its own power from batteries, and you have to change those now and then.

    In my house, the thermostat wire run was really simple, through a crawl space and up one wall, and I just bought some new thermostat wire with more conductors, taped it to the end of the old stuff, and pulled it through. I pulled ten-conductor thermostat wire, because some modern thermostats now can do more than signal for heat, cool, and fan. They can signal for high heat, low heat, high cool, low cool, fan, humidify, and dehumidify, and measure the temperature outside.

    Pulling new wire in my house was super easy. But in some houses it would be a real job.

    Then you might not mind paying extra for a special thermostat that would totally work over the old 4-wire cable, just by repurposing the 4 wires. It will typically use two of them for power and ground, and the other two as a special communication circuit, and the heating/cooling system specific to the manufacturer will understand that.

    (Toyota did something similar in the Gen 3 Prius with the "touch tracer" steering wheel controls. There are only 4 conductors passing through the spiral cable for those. In the non-touch-tracer models, those wires are just pulled to ground by the wheel buttons through some resistors. In the touch tracer models, where they had to send more different signals over the same 4 wires, they just put an extra computer inside the steering wheel, used two of the four wires to power it, and the other two as a communication circuit where it sends messages to the combination meter about what buttons are being touched or pressed.)

    Honeywell has some nice non-brand-specific thermostat models that work that way too. The thermostat comes with a box with the ten or so control terminals that you just easily mount next to the HVAC equipment itself. It uses your existing 4-wire stat wire to communicate with its own matching thermostat at the other end. That gives you the same benefit of not having to pull new wire, getting all the control signals of a modern thermostat, but without being tied to any one make of HVAC equipment.

    Sometimes there can be another point in favor of the proprietary manufacturer thermostat. My gas furnace has a modulating burner: it can burn anywhere from 20% to full fire. If I had bought the special thermostat from the same maker, the stat would be able to tell the furnace exactly what firing rate to use, not just signal no heat/low heat/high heat. The stat could learn that when I want x inside temperature and it's y outside, firing rate z will work best and keep the furnace just steadily operating. Or if I come home during the setback period and I bump the setting up several degrees, the stat can send the furnace to full fire right away to quickly make that several-degree change.

    As it is, controlling my furnace with a non-manufacturer-specific stat, there are some tricks the furnace uses to guess what firing rate to use. So it usually guesses "about the same as last time". If the thermostat's call for heat ends sooner than it did last time, the furnace guesses "ok, maybe a little lower fire next time." Or if it goes about as long as last time and sees the stat is still calling for heat, it will start to nudge the firing rate up slowly. If it's firing at a fairly high rate and then the stat says enough, the furnace will actually keep firing at a very low rate and see if it can figure out a steady rate that keeps the thermostat asking for heat on a steady cycle. In the case where I come home unexpectedly and bump the setting up several degrees, it might be 15 minutes or so before the furnace has figured that out and is running full fire. But it works Well Enough, and avoided going with a brand-specific stat.
     
  15. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I needed the C wire for my WiFi Honeywell thermostat upstairs, but it is on the same wall as the unit so pulling it was easy.
     
  16. kenmce

    kenmce High Voltage Member

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    She did mention having natural gas. Maybe she just has an A/C outside?
     
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