Replacing the switch.
All homes built in the US after 1985 are required to have a neutral to every light and outlet box.
Post a picture of the plate. I suspect that you may have to make your own switch with a rotary knob.
House built in the 1930’s. The rotating nob or toggler would be on the left side (the right will be controlling something else).
@stevemann I am handy and more than happy to make my own, if possible…
The shelly product mention before is what you want. You pull the switch out of the wall, wire in the device and put it in the back of the box and then put your existing switches back in and wall plate back on. Everything looks the same but now it’s smart.
Actually depending on how wiring is done at the switches in your house, if there is no neaturl wire at the switch then you place the device in box at the light side.
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@bkprath we are talking about the switch on the left side only to be replaced with a smart dimmer switch. I have alot of shelly’s all around the house and I love them. The issue here is that we are replacing the dimmer switch on the left with a smart dimmer. I would rather not replace it with a dumb switch and then be able to only dim it remotely through the shelly. People need to be able to dim it from the dimmer switch itself as well - I need both…
Shelly also has this device that might give you what you want. I use a lot of kasa products and they have this switch you could possible use. In both cases you’d need a different wall plate. Here’s a thread on the Kasa hs220.
A Shelly Dimmer 2 will do that for you though. To complete your setup you just need a toggle style double throw, center off, momentary contact switch like the Leviton 1257. The Shelly can then be configured to enable the actions you need.
For example:
- flick up: light on
- hold up: brightness up
- hold down: brightness down
- flick down: light off
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Not sure if my ‘trick’ using a piece of foam is feasible on your type of switch, but in my case it worked… so i changed my DPDT switch i to a SPDT switch just by placing a piece of foam under the switch cover 
it was for sure a lot cheaper then replacing the whole switch 
Maybe it is possible to do something similar with a piece of elastick or a spring?
@FelixKa , use case question - when the person holds the toggle in the up position, if not already fully bright, the light would continuously get brighter until they let go, and visa-versa with holding it down?
Yes. Pretty intuitive.
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@FelixKa I have a Shelly Dimmer 2 and a Leviton 1257 being delivered shortly :-), which will both now go on the left side of that picture. Do you know where i can get a wiring diagram/picture for this specific configuration?
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This scenario should be the top right of the 4 diagrams found on the Shelly Dimmer 2 documentation titled “No neutral wiring”.
For the SPDT switch it’s pretty much exactly as shown in the diagram: You’d run one L from one of the L terminals on the Shelly to the L1 on the Leviton and then A1 from the Leviton back to the Shelly on SW1 and B1 to SW2 (or the other way around, depending which way around you install the Leviton).
If in doubt always ask an electrician.
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Perfect @FelixKa I should have done all my dimmers this way, I’ve got a couple others in the house that are the ugly “modern” kind (wife prefers the look of the old switches). If this goes well I will then go back and replace those too… I’ll let you know when it’s all done and how it goes, some of the spare stranded cables that I ended up using between the shelly and the switches are overkill - wrong gauge, actually too thick - so I started having to remove some of the strands at the end for the shelly so they would fit - but when a switch box is very crowded with very thick stiff wires (and in this old home some have cloth insulation that is starting to come undone) then it would get gnarly (I felt like a cave man wrapping electrical tape around so many of those old wires) and with the occassional wire ends almost touching right where they go into the shelly - so I would end up putting electrical tape between the wires where they connect to the shelly’s afterward as well…
I did recently wise up and got both heat shrink tubing for the wires with the disintegrating insulation, and a ferrule crimping kit so I don’t have to worrry about forcing fat stuff into the shelly’s and trying to handle it by overtightening those screws. Live and learn… 
I moved to North America from Germany somewhat recently and have developed a love/hate relationship with how electrical systems are done over here. The great thing is that here our walls are mostly hollow and that makes it easy to fix stuff, the downside is that any electrical fire has a much greater risk of creating damage than it has in solid concrete or brick walls that I know from Germany.
Also my kettle takes 10 minutes to boil 1.5L of water. That took me 3 minutes in Germany. Oh the joys of 120V/15A vs. 230V/16A…
To add to that: Shelly devices were primarily made for the European market. I put some in my parents house in Germany, don’t actually have any in my house in Canada. Germany uses 1.5mm² wire (roughly 16 AWG) which may be why the terminals are a bit snug for the 14 AWG we generally use over here.
I think the cables I bought for the extra leads I needed are probably actually 12 AWG - lol
Anyway, regarding your comments about the stoves - that I why I have always preferred gas stoves - the flames seem to heat alot faster - than the electric. Some electrical things over here are 220V such as heavy duty wall air conditioners and the like - and I thought that maybe was the case with the electric stoves here as well, but I guess not.
Reminds me of a funny story. When we first moved into this house, we had one of those old wall unit air conditioners in the master bedroom that was 220V - but it was using the improper plug and outlet - 220 V running through to it with a standard 110v outlet and a 110v style plug at the end of the wire coming out of the air conditioner. We did not know this about the air conditioner - so, my wife saw the outlet (the air conditioner on the wall right next to it must have been unplugged) - and proceeded to plug her 110V hair blow dryer into the 220V outlet and tried to use it… I heard some loud yelps from the other side of the house and came running - as soon as she turned it on, alot of loud zapping noises and a bunch of nice scorch marks on the wall. YIKES! Fortunately that is all that happened. (Other than replacing all that - and then upgrading the electric for the whole house to 150 amp and replace all the fuses with circuit breakers - you have to do that when it keeps getting dark because three girls fighting over blow dryers when someone tries to use a vacuum cleaner) Sheesh!
You could have bought a stone or brick house - but of course that resolves the issue you mentioned only for the external walls. You might be able to find an old castle over here (but over here nothing is really very old either)!
I have fallen in love with Shellys, they rock
@FelixKa , I was hoping to install tonight and report back with success. However, I ran into issues and am exchanging this Dimmer 2 which is at least partially defective with another unit to give it another try. The “O” terminal screw works perfectly only when there is no wire in it, meaning it can tighten, but when it is loosened and then a wire is inserted, the screw spins around and around clockwise but does no tighten, so it looks like there were some damaged threads possibly.
Even so, I thought I would try to just get it to work, and had a very strange experience which I want to avoid a second time. As there is no neutral and no bypass, I replaced the LED bulbs with incandescents first, and was able to add it to the app (and connect the switch to it) and was able to control it from the app. Before I tried to configure the software for the switch however, I thought I would just for fun try the LEDs, but it flickered, so I put the incandescents back in place, and it continued to flicker. I lost connectivity to the shelly from the app, and pressing the reset button on the back of the unit or taking out and replacing the power wires and flicking the switch even 50 times within 60 seconds of resupplying power to the Dimmer 2 does not reset it at all. The reset button on the back of the unit has no effect, the incandescents would still flicker and the LED on the back of the unit no longer lights up. Not having the right kind of bulbs in a fixture should not break the dimmer. Will that happen again if I replace all the bulbs with new ones at one point so it has no bulb in there at all for a short time? And when I was trying to configure the switch, the I/O action settings for holding it or tapping the switch for every option talks about a URL… What URL and why do I need a URL? and with Leviton 1257 should the switch be set as edge or what? Sorry to sound so thick but it’s ridiculously confusing and having a light bulb or not in the socket should not damage the Dimmer 2… What a ridiculous mess? Is it possible if the configuration settings in the Shelly App for the Leviton 1257 are not set correctly, that would actually brick the Dimmer 2? WTF?? I did find the 4 diagrams only in the multi-language version, but both the English version and the version that came in the box only have three pictures. So on the other replacement that is coming, how do I do this without damaging it so it can’t be reset - just never ever ever get into a situation where the bulbs are not unscrewed? (The bulbs currently in place now are three 25 watt incandescents…)
Oh no, that sounds like a vexing experience!
Not quite sure what’s going on there but it may be that you do need a bypass in your setup. Flickering can indicate a bypass is needed in a no neutral scenario. The bypass can be installed in the light fixture if you’re running out of space in the box. But I’m not an electrician, so this is outside my wheelhouse. No warranties
That being said, having no bulb in the fixture while also having no bypass installed will just lead to the Shelly not being able to draw power from the circuit as it is incomplete. So, no, it shouldn’t damage it.
I recommend updating the firmware as a first order of business. There have been fixes in the past that relate to how LEDs are dimmed and that could potentially damage the device if configured incorrectly.
As for setting the Button Type under “Settings” in the App: For the setup you’re intending to run with the 1257 the correct setting would be “Dual button mode”.
This should be the only setting you would need to change. The whole URL shenanigans are basically for when you are looking to do custom integrations with other things. You don’t need to configure this to run the dimmer from the wall switch or app. For Home Assisstant the steps are outlined here: Shelly - Home Assistant
Not having set the Button Type will not damage the dimmer, if the switch is wired up correctly.
I hope you’ll have a better experience with the replacement. Again, if in doubt ask an electrician.
Thanks @FelixKa I did morte digging and I thoughyt that is what you awere going to say about the URL’s… The replacement should be here tomorrow, it could be it just didn’t have enough power to turn on (which surprises me with three 25W incandescents) and It’s a big fixture to take apart (large ceiling fan although this switch is just for the lights under it only) and the wife likes brighter lights so I’m replacing them with 60w bulbs so it may be moot. Even if it was malfunctioning just due to the wattage too low, my conscience is clear as I needed to exchange it due to the broken threads on the “O” screw anyway…
I’ve got some bypasses from several manaufacturers and since they are not specifically for Shelly I have had mixed results with them. Shelly doesn’t sell bypasses in the US any more, and the ones they still are selling are for non-USA setups with 220 V.
Even the most recent two Shelly 1L’s I needed I had to get them shipped from Spain as they don’t directly sell them in the USA any more. On the facebook Shelly support group the Shelly CEO actually responded to me they had 5 engineers and 2 qa testers actually fighting in their office about the design on a replacement for the 1L and ended up restartin the design from scratch 3 times, but are almost done with a newer better type relay to replace the 1L that if all testing goes well would go into production in May.
@FelixKa, thanks for all your help - I forgot to come back here and tell you what my results were… everything works fine except for one surprise and three issues. The surprise was that although I have SW1 connecting to A1 and SW2 connecting to B1 - and the switch is installed in the receptacle with the A1 on top (which I believe is right side up) I had to swap the inputs in the configuration to make Up ON and down OFF. lol… #2 and #3 below seem like minor inconveniences and I don’t mean to be picky but it is almost perfect and resolving these would mean I am done… so my three issues are:
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TOO HOT: When light is off, the temp is about 75-85 degrees F (great). When the light was ON, (after installation and first updating the firmware) it first would skyrocket up to ~205 degrees F. Tweaking everything to death including every possible type of calibration, the lowest I can get it to is a steady ~180 degrees F which is still much to high. It does work perfectly (except issue #2 & 3 below) - and the fact that it won’t have a very long lifetime if it is forced to run that hot when in use. I did reach out to Shelly tech support and they took three days to respond, askng for more details on the wiring and the exact setup and configuration and status logs - all of which I supplied - and still waiting to hear back… probably will get a response in 3 days again…
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TOGGLING!?? When the light is on and I do a short press in the up position (which turns it on) - it would go off. If the light is already on and someone does a short press in the up position - ideally nothing should happen, it should stay on. Also, if the light is off, a short press down will turn it back on again - but ideally that should just leave it off. Someone suggested for the url for the short press for each, for the down button I should enable the short push url to ‘http://localhost/light/0?turn=off’ and the same except ending in “on” for the up short push url. This would have resolved the issue but a similar issue still exists for these two use cases - if the light is off, and a short push down is done, now the light will still go on any way and then immediately it will then go back off (executing the url comand I guess). Same type of issue with the up push with that url “workaround” enabled…
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DELAY: I have gotten questions and confusion from people living here - about why there is short delay when the button is pressed before the light goes on - and same thing when off. How can I reduce that to no delay (as it is now confusing when turning it on (for the very first time only), people push up, they don’t see an instant response, so then while it is coming on they push up again and it turns off… (but with my url workaround it at least just flashes before remaining in the correct state, but still)?
So, @FelixKa, your thoughts about #1-3?
Those temperatures don’t look healthy, I agree. Let’s see what the manufacturer comes back with for an idea.
I don’t have a workaround for the toggling scenario. Maybe something the Shelly Community on Facebook knows an answer to?
As for 3: The delay may come from double click events being active. I think by default they cause the light to turn on at full brightness. To allow for double click events to happen the Shelly will have to wait a moment to see if another click is coming in before performing the single click action if there is no further click.