Automated Bed Warmer Control For Chilly Nights

For most of the Northern Hemisphere, winter is in full swing right now. That means long, chilly nights. We assume [LC] is in one of these climes because it seems like his bed warmer wasn’t doing quite a good enough job of getting his bed up to a reasonable temperature before he climbed in. To alleviate some of his discomfort, he hacked into the control unit and added some automation.

The original controller uses a mechanical potentiometer to set the heat level. [LC] added a digital potentiometer which he can switch to in order to allow the automation (using a real-time clock to handle scheduling) to take over control of the bed warmer. This also preserves the original functionality of the controller. There is also an Arduino involved which handles the override from mechanical to digital potentiometer when a capacitive touch sensor is activated. This means that when someone attempts to take manual control of the device, the Arduino can switch the override circuit off.

There is quite a bit of detail on the project site about this hack, including the source code for the controller. [LC] also mentions that this could be interfaced to the web to allow remote control of the bed warmer. This is a great hack, and also fits into the idea of heating the person, not the room.

13 thoughts on “Automated Bed Warmer Control For Chilly Nights

  1. Not to dis the ‘duino, but the warmer is likely line operated and the pot is too.
    What’s wrong with just setting a plug-in timer to the right preheat to have toasty toes.
    I once stayed in a house with a gas stove (one room) and slept in the cold room. So I took a hose style hair dryer set (low) at 150watts and ran it off a Variac at 20 to 30 percent and ran the hose into the toe end of the sheets.

    Since your metabolic rate varies the best design will have a way of monitoring temperature undercover, preferably without wires.

    1. It’s stated in project details that pot feeds the controller IC with 5V max. The idea with plug-in timer is cheaper and simpler but won’t work if you have to manually press On/Off and Preheat button every time.

      Wireless temperature sensor would be quite neat, but i would find it a bit uncomfortable unless the sensor is really small and put in the right place. Wired temp sensor with wires run along existing ones would work and be cheaper than wireless unless you have to pry open the bed warmer to put it into “good spot”.

    2. I can understand the idea of heating up a cold bed. I lived in a unheated bedroom in the basement for a few months, had to pay for utilities and I was out of school and before job poor. Yes we do have lots of snow here.

      If your blanket has to be electrically heat all night, then there isn’t enough insulation. I reused my (unzipped) sleeping bag as a blanket and that was warm enough after that initial few chilling minutes. Sleeping bag material is light and has good insulation to around freezing.

  2. Personally, I can see some use for this. eg, initial power-on state – my own blanket comes on at ‘standby’ when initially powered. So a wall-wart timer won’t do much. The second thing that jumps to mind is a kind of profile-over-time. Personally, I crank it up max, go take care of the bathroom, then come back, turn it down to 1/3rd, and then set the 1hr timer.

    This project could pave the way for some interesting automation. eg, I have those Philips Hue lights. so a http/json api can poll the status of my bedroom lights. This could tie together into some “when I turn my lights off, begin a ‘fade to zero’ over a 1hr period”.

    Automation doesn’t have to be overly complicated gizmos – but when you start gluing them together, is when it starts to look like magic.

    1. I like the idea of sleep temperature profiles a lot! I did think about this early on, and I might do some more work on it. I think part of it at least might be accomplished by adding a room temperature sensor, and then adding some logic that says for example: “if it warms up in the room by X %, turn down the heat X %, and conversely, if it gets colder, turn the heat level up X %”. How much to increase or decrease is highly subjective, so it would obviously need to be a user customizable “sliding scale”.

      1. Yes pre-heating the blanket before you get in bed seems like a waste of energy since they are able heat up so quickly. Though there are other more useful automation ideas like the ones mentioned. Good project.

    1. Female human checking in here to say that I’m totally going to perform this hack on our mattress pad so that my male human will pipe down about the bed being too cold. Neither me nor the dog is willing to go to bed an hour before he does.

  3. Drink some water and eat a snack before bed, also buy a good thick wool blanket to go over your other ones. Then you won’t need to waste electricity. Or do like I do and keep one dog in the bed who likes to be under the sheets.

  4. Electric blankets are a significant fire hazard.

    I woke up one night to the sound of electrical buzzing and a smell of smoke. I then googled around, read about all the fires these things cause, threw it in the trash, and never bought another. I bought a better (normal) blanket.

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