When your heater ignores the thermostat: what would you do?

Had a similar issue last winter when my heater just wouldn’t respond to the thermostat. Everything looked fine - wires seemed intact, no obvious damage. I figured it was the thermostat itself, but after swapping it out, still nothing. Pulled out a cheap continuity tester and, sure enough, found a break in one of the wires inside the wall. Never would’ve caught it by just looking. I’m always skeptical about spending on extra tools, but that tester paid for itself right there. Sometimes you really can’t trust what you see...

I’ve actually wondered about hidden wiring issues myself - seems like you can’t always trust what’s behind the walls. I usually try to troubleshoot step by step: check the thermostat, then the breaker, then the wiring connections at both ends. But I’ve never used a continuity tester before. Did you have to cut into the wall to find the break, or was it enough to test from the ends? I’m always a bit hesitant to start poking around in the drywall unless I’m sure.

You’re right to be cautious about cutting into drywall - once you open it up, there’s no going back without patching. In most cases, a continuity tester will let you check the wiring from end to end without opening the wall, as long as you can access both connection points. If you get no continuity, then you know there’s a break somewhere in between. I’ve only had to cut in rare cases where the wire was stapled too tight or damaged by a nail. Always make sure power’s off before testing, though... safety first.

I get the whole “don’t cut unless you have to” thing, but honestly, sometimes it feels like you’re just delaying the inevitable. I tried using a continuity tester when my heater started ignoring the thermostat, and yeah, it told me there was a break somewhere, but it didn’t tell me where. Ended up having to open the wall anyway, which was a pain. Maybe I’m just unlucky, but I feel like these “non-invasive” methods only get you so far before you’re patching drywall regardless.

Here’s what I’m wondering: if you do find a break or damage in the wire, is it ever worth trying to fish a new wire through the wall, or is that just asking for more trouble? I’ve heard some people say it’s easier to just run surface conduit, but that looks pretty ugly in a living room. I’m not super handy, so the idea of snaking wires behind walls is kind of intimidating. But at the same time, I don’t want to keep patching holes every time something goes wrong.

Also, has anyone actually found a break with a tester and managed to fix it without opening up half the wall? Or is that just wishful thinking? I feel like once you start down this road, you’re either living with a janky workaround or you’re knee-deep in drywall dust. Maybe I’m missing some trick here...

I feel like these “non-invasive” methods only get you so far before you’re patching drywall regardless.

I get where you’re coming from - last winter, I tried to trace a break in a thermostat wire using a tone generator. It narrowed it down, but not enough to avoid cutting. Fishing a new wire is doable if the old one pulls freely, but in older homes, staples or tight bends can make it a nightmare. Surface conduit just isn’t worth it for main rooms, in my opinion. Sometimes, patching a couple of small holes is less disruptive than living with exposed wiring. It’s a tradeoff, but I’d rather deal with drywall dust once than look at plastic raceways forever.

Honestly, I’ve tried the “let’s keep the walls pretty” approach, but it always seems to end with me covered in dust anyway. Last time I had to run a new wire for a baseboard heater, I thought I’d be clever and use the old wire to pull the new one through. Of course, halfway through, it snagged on something - probably a staple from 1972 - and I ended up with both wires stuck in the wall. Cue the drywall saw.

If you’re patching small holes, it’s not that bad. A little mesh tape, some mud, and you’re golden after a couple of coats. Way better than staring at those plastic channels forever. I get why people try to avoid cutting, but sometimes you just gotta accept that a bit of patching is part of the job. At least you get to learn some drywall skills along the way... silver lining?

Yeah, I hear you on the patching. I always start out thinking I’ll keep everything neat and then end up with a pile of dust and a new appreciation for joint compound. Honestly, those plastic channels just look weird to me anyway. At least with a patch, you can pretend nothing ever happened... unless you’re like me and forget to sand it smooth.

I get what you mean about the patching - my first attempt looked like a lumpy pancake on the wall. I kept thinking, “It’ll sand out,” but nope, just made more dust. Reminds me of when I tried to fix a thermostat wire and had to cut into the drywall. Ended up spending more time making the patch look halfway decent than actually fixing the wiring. Those plastic channels are supposed to be easy, but they always stand out like a sore thumb to me. At least with a patch, if you squint, it’s almost invisible... unless you catch it in the wrong light.

At least with a patch, if you squint, it’s almost invisible... unless you catch it in the wrong light.

- Been there. No matter how careful I am, the patch always shows up when the sun hits just right.
- Those plastic wire channels never blend in - paint helps a bit, but not much.
- Honestly, I’ve found running new thermostat wire behind baseboard can be less hassle than patching drywall holes. Not always possible, but worth checking.
- Did you use mesh tape or just mud? Mesh helps smooth things out, but it’s still a pain to feather the edges.
- Sometimes I wonder if it’s just easier to call it “character” and move on…

Patching drywall is one of those things I always think will be a quick fix... then the sun comes in and suddenly it’s like a neon sign pointing to my “repair.” Mesh tape does help, but if you don’t feather it just right, it can still look off. I’ve tried both mesh and paper tape - honestly, neither is magic. Sometimes it’s just about how patient you are with sanding (which is never enough, in my case).

Running wire behind the baseboard is a solid tip. I’ve done that a couple times, and it’s way less headache than trying to hide a patch in a visible spot. Not always doable, especially in older houses where the baseboard’s basically glued on with a century of paint, but when it works, it’s so much cleaner.

Those plastic wire channels drive me nuts. Even with paint, they always stand out. I get why people use them, but they’re kind of like putting a band-aid on a cracked window - does the job, but you’re not fooling anyone.

Honestly, sometimes I just leave small imperfections and call it “vintage charm.” Life’s too short to chase invisible patches, especially if the heater’s actually working. But if the heater’s ignoring the thermostat, that’s a whole other headache. Nine times out of ten, it’s a wiring issue or a bad connection at the stat. Once had a job where the wires were patched together with electrical tape and prayer - surprised it worked at all. Re-running the wire fixed it, but yeah, more drywall fun after.

At the end of the day, I’d rather have a working heater and a slightly visible patch than freeze with perfect walls. Priorities, right?

At the end of the day, I’d rather have a working heater and a slightly visible patch than freeze with perfect walls. Priorities, right?

Totally get this. I used to obsess over making every drywall patch invisible, but after chasing my own tail for hours (and still seeing the seams in certain light), I just gave up caring so much. The “vintage charm” excuse is underrated.

Had a similar heater issue last winter - thermostat was basically just a wall decoration. Turned out to be a loose wire at the furnace end, not even at the stat itself. Took me way too long to figure out because I kept assuming it was the thermostat or the wiring in the wall. Ended up pulling off a chunk of baseboard and, like you said, it was glued on with layers of old paint... that was a whole project by itself.

Curious if anyone’s ever tried those wireless thermostats? I keep seeing ads but can’t decide if they’re worth it or just another thing to troubleshoot when things go sideways.

Wireless thermostats sound slick, but honestly, I’m not convinced they’re all they’re cracked up to be. I’ve seen too many “smart” gadgets end up being more hassle than help - especially when you factor in spotty Wi-Fi or weird compatibility issues with older systems. Give me a hardwired stat any day. At least when something goes wrong, you can usually trace the problem without needing an app update or a new router password... Just my two cents after crawling around in too many basements.

Give me a hardwired stat any day. At least when something goes wrong, you can usually trace the problem without needing an app update or a new router password... Just my two cents after crawling around in too many basements.

You’re preaching to the choir here. After wrestling with a “smart” thermostat that decided to go offline every time someone microwaved popcorn, I keep a trusty old-school one in my toolbox. Hardwired might not get you fancy graphs on your phone, but at least it doesn’t ghost you when the Wi-Fi hiccups.

Here’s my step-by-step when a heater ignores the thermostat:
1) Check batteries (if it’s got ‘em). Sounds basic, but I’ve had tenants swear their “smart” stat was haunted, only to find out it just needed fresh AAAs.
2) Wiggle the wires. Gently. Sometimes those connections get loose, especially if someone’s been poking around in there.
3) Bypass the stat with a jumper wire - see if the furnace kicks on. If it does, bingo: thermostat’s the culprit.
4) If none of that works, time to crawl back into the basement and stare at the furnace until it confesses.

Wireless is flashy, but sometimes simple really is better... or at least less likely to make you want to chuck your phone across the room.

Hardwired might not get you fancy graphs on your phone, but at least it doesn’t ghost you when the Wi-Fi hiccups.

That’s exactly it. I’ve had “smart” stats that needed firmware updates before they’d even turn the heat on - meanwhile the old Honeywell just keeps chugging. My checklist looks pretty similar to yours, though I’ll add: if you’re dealing with baseboard heaters, sometimes the wall stat’s relay sticks. A couple gentle taps can wake it up (not exactly scientific, but it’s worked for me). Tech is great until it’s not... then you’re back to basics anyway.

Had a similar thing happen last winter - brand new digital stat, but the relay in the heater itself was the real culprit. Ended up swapping it for an old-school mechanical one just to get through the cold snap. Sometimes the “dumb” stuff is just more reliable, honestly.

Sometimes the “dumb” stuff is just more reliable, honestly.

I get where you're coming from. Mechanical stats and relays might not have the bells and whistles, but at least you know what you’re dealing with when something goes sideways. Digital setups can be a bit of a black box - if the relay’s bad, you might not even realize it until you’ve already swapped out the stat or spent time chasing wiring that isn’t the problem.

Curious if you noticed any intermittent behavior before the relay fully gave up? In my experience, those relays sometimes stick or buzz for a while before they fail outright, but digital thermostats don’t always give clear warning signs. I’ve seen cases where a digital stat showed it was calling for heat, but the relay just sat there doing nothing - makes troubleshooting a real headache.

Have you found any good way to test those relays in place, or do you just go straight for replacement when things get weird? Sometimes I wonder if we overcomplicate things with all this smart tech...

Honestly, I get the appeal of old-school stuff, but I’ve actually saved money with a digital stat. Here’s my take:

- My programmable one cut my bill down, since I’m not heating an empty house.
- When it acted up, I just swapped batteries and it was fine - no tools, no fuss.
- If a relay goes, yeah, it’s a pain, but at least I can Google error codes instead of guessing.

I do keep a cheap analog backup in the closet, though... just in case the “smart” part decides to get dumb.

I get where you’re coming from - digital thermostats have come a long way, and the energy savings are real if you set them up right. I’ve seen a lot of folks surprised by how much they save just by programming a setback schedule. But I’ve also run into situations where the “smart” features get a little too clever for their own good. Had one customer whose WiFi stat decided to update itself in the middle of a cold snap... suddenly, nothing was working and the house dropped ten degrees before we figured out it was just a firmware glitch.

Honestly, I always recommend keeping that analog backup handy, just like you do. When things go sideways, sometimes it’s faster to pop in the old dial and get heat running while you troubleshoot the fancy stuff. Digital is great for efficiency, but when it comes to reliability, those old-school stats are hard to beat. There’s something to be said for simplicity - less to go wrong, and you don’t need an app or a manual to figure it out.

That firmware glitch story hits a little too close to home for me. I just moved into my first place last year and went all-in on smart everything, thinking it’d make life easier. Most of the time, it does - until the day my thermostat lost WiFi during a storm and basically just froze up. I had no clue what was going on, and honestly, I kind of panicked when the temp started dropping and nothing responded. Ended up digging out the old mercury dial from a box in the basement (didn’t even know we had it) and swapping it in just to get some heat back.

I totally get the appeal of the tech, especially with energy bills being what they are, but you’re right - sometimes simple is just more dependable. I kinda wish these companies would build in a “dumb mode” for emergencies, like a hardwired override or something. Until then, having that backup stashed away seems like the move. It’s not glamorous, but neither is freezing at 3am because your thermostat decided to update itself...

Honestly, you handled that way better than a lot of folks would - most people wouldn’t even know where to start if their smart thermostat just quit. Having the old mercury dial around probably saved you a ton of hassle (and shivering). I get what you mean about wanting a “dumb mode” or manual override. It’s wild to me that these companies don’t make that standard, especially since power and internet outages aren’t exactly rare.

I’m always a little wary of putting too much trust in tech for stuff like heat or security. Do you think you’ll stick with the smart setup long-term, or maybe keep the backup ready just in case? I’ve seen some people wire in a bypass switch for emergencies, but that’s not exactly beginner-friendly… Still, it’s good you had an option. Sometimes old-school is just safer, even if it’s not as sleek.