Given the electrician's description, can I use this thermostat?
September 8, 2024 7:51 AM   Subscribe

Previously I asked for advice here on getting new thermostats for our baseboard heat. Eventually had to hire a electrician, who gave us a report but flaked when it came time for an actual quote. I think I could just install thermostats myself but I want to make sure I'm buying the right one.

Here's the relevant section of the electrician's report:
Service all today to check the 220v electric baseboard heaters, it was mentioned that you tried replacing one of the stat with a240v but it didn’t seem to work, also the living room thermostat is no longer reading correct and the bedroom baseboard didn’t seem to be working, and the office thermostat was no longer connected. I checked operation of each baseboard heater and all responded normally. When the voltage was tested at the thermostats I was reading about 24v and the existing thermostats are rated for 30v. Further inspection found the baseboards to have transformers in the control panel.
Given this information, it looks like I was correct in my previous post when I guessed that I am very bad at reading a multimeter. could I install this thermostat and have it work? I like that it's programmable but not a wifi-internet-of-things piece of junk.
posted by HeroZero to Home & Garden (8 answers total)
 
Sorry, editing to completely change my answer: the item description says it doesn’t work with electric baseboard heat. So probably not a good choice.
posted by mskyle at 7:57 AM on September 8


Response by poster: Yes, but my impression was that the reason for that labeling is that baseboard heater thermostats are generally wired at a full 240v, whereas this circuit is at 24v. So I guess that's my real question -- does the "don't use this 24v thermostat for baseboard heat" labeling actually apply here?
posted by HeroZero at 8:04 AM on September 8


Best answer: How are the old thermostats connected? Two wires, relatively thin, like for hooking up a doorbell? Or differently? Can you post a photo?

If it's two wires and you measured somewhere around 20V, not 200V, the thermostats are controlling relays that do the actual power switching. Which is consistent with what I distilled from the electrician's report, and means that the thermostat just has to deal with the current and voltage to drive the relay, and the unit you linked here can do that.

As a test you could (again, only if there are two thin-ish wires) touch them together, which should cause the relay to close (you should hear it click) on the control panel and the heat should come on. If so, the Honeywell thermostat you linked to will do the job just fine.
posted by Stoneshop at 8:39 AM on September 8


Best answer: Any low voltage thermostat, including the one you linked here, will do the job. It's pretty clear that you need a low voltage thermostat from the report (voltage at the thermostat was 24V, transformers found in the baseboards).

Low voltage (24V) thermostats are all going to be designed to work with furnaces, so it might seem like they are wrong, but you can still use them with your baseboards. A standard baseboard thermostat (line voltage) will not work, you need a low voltage thermostat because you have a somewhat non-standard system.
posted by ssg at 9:12 AM on September 8


Response by poster: Thanks all. Going to try these thermostats and will report back.
posted by HeroZero at 10:29 AM on September 8


If you have 220v electric baseboard heat, you need to use a thermostat rated for 220v. This is the thermostat I have for my baseboard heaters. I have replaced two myself, plus a bathroom heater with a built in thermostat. You need the special thermostat because your send two hot wires through the thermostat to the heater. Please don't burn your house down.
posted by DEiBnL13 at 9:20 PM on September 8


Best answer: you need to use a thermostat rated for 220v.

Only if you have standard baseboard heaters. These aren't, they need a low-voltage thermostat as per the electrician's report, and the fact that (it's in the previous Ask) a standard 220V thermostat was found not to work.
posted by Stoneshop at 2:10 AM on September 9


Response by poster: Two wires only. The Honeywell thermostat linked above works fine. Thanks all!
posted by HeroZero at 8:28 PM on September 9


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