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#205824
We have a cabin up in northern Minnesota and we like to turn the gas valve for the kitchen off when we're not there to keep things a little safer. But the valve is on the outside wall and especially in the winter it's a pain to get to it through all the snow so I'd rather have some kind of a switch inside I could just use to turn it on and off whenever I want.

I could 3D print a sort of mechanical adapter to replace the little blue handle on the valve, but I’m not sure what the best device is to use to actually turn the valve. It just has to move 90 degrees back and forth. Is a servo the right tool for the job, or could it be simpler to use some sort of motor? And what’s the right way to detect when it has turned all the way to the limit in both directions? Can I be super crude and just hold a button down for a few seconds and let the motor jam when it goes to the limit? Or is that dumb? And what’s the easiest way to go in reverse?

The valve turns relatively easily, so not a lot of torque is needed. But I suppose in the bitter cold it might get a bit sticky sometimes. If I could make something simple that just needs a hole drilled through the wall for wiring, that would be really handy. Thanks for any ideas! Steve
#205827
Hi shighland!

Since you're working with gas, it would probably be best to use a purpose built electric gas valve so you know it's working exactly the way it should. If you know anyone that works in heating and cooling or that does gas fireplaces, they could probably get you a working valve from a junked furnace or fireplace. You can also buy them new on the internet or from a heating and cooling contractor. Check the valve you get, but most of them run on 24 volts AC and any large hardware store will carry 24 volt transformers you can use to power the valve.

If you want to try and hack a servo onto your existing valve, I'd go with something like our Servo Trigger, a large servo, a toggle switch and a 5 volt power supply. You'd need to figure a way to connect the servo up to the handle on your valve but the Servo Trigger can be programmed with the on and off positions and only needs a switch to change from on to off.

The parts below along with a few other miscellaneous bits would be what you need.
#205829
Make sure whatever solution you come up with is failsafe. There are two cases to deal with - turning the gas on when you don't want it on, and preventing turning the gas off.

To avoid accidental activation, I would make sure power is disconnected when you are not there. In addition, similar valves often use a motor to open the valve, and a spring to close it if power fails. You can find this style often used with hot water heating systems.

As for preventing turning it off, I would have a way of rapidly disconnecting the motor and having the handle still be present. That way, if the power is off or the control mechanism fails, you can still turn the gas off.

I would also look into a purely mechanical system with a bowden cable, like you find on lawn mower throttles or bike brakes. Less to go wrong there.
/mike