Skip to main content

Door-actuated space heater power lockout

Here's a little project I did last night:

Power strip modified for dry-contact switching

Magnetic switch on the door
I'll try to keep this short: due to some insulation issues in the garage under the second floor, Henry's room gets kind of cold in the morning.  This is not compensated by the house thermostat because it's in our room and we sleep with the doors closed.  So we use a little electric space heater to regulate the temperature in Henry's room at night.  With this comes a couple of problems:


  • Heater can be left on in the morning
  • If the door is open, the heater then runs open-loop and tries to heat the rest of the house 
  • The heater will run all day long, if it's set to even 1 degree above the "house" temp.  
  • This costs over $.25/hour
  • It's also (more of) a fire hazard since the heater will potentially be running when no one is in the house
I thought of a bunch of different ways to solve this problem.  Sure, go ahead and tell me about how the best way is to "turn the heater off when it's not needed".  Great, it's not going to happen. The next option I picked is the one that, to me, made the most sense.  Basically the heater power is disconnected when the door is open.  Since the door is always left open during the day, the heater won't run, and even if the door is closed, it's fine since the heater won't run "open-loop" (indefinitely).

To do this I modified a power strip and replaced one of the outlets with a 20A solid-state relay.  These relays are crazy - totally isolated and able to handle a lot of load. Since there aren't any moving parts, they don't wear out and you can switch them with very little current.
Solid State Relay



I wired two of the power strip outlets to the "load" side of the relay, and then installed a 9v battery and some contacts to the side of it.  Then I installed a magnetic switch on the door which will switch the 9v to the control side of the relay.  I was really careful to do everything really cleanly, since this is going to be in my kid's room.  (Don't want some wire  to come off and electrify the power strip case to 110v or something). So it took a couple of hours to build, but I am really happy with the result. It's almost invisible in the room and it works like a charm.

Comments

Popular posts from this blog

Timbaland rips off a Demoscene artist

I knew this day would come. The new Timbaland/Nelly Furtado song "Do It" uses a song made in 2000 by Finnish demoscene artist "Tempest" (Janne Suni). It's a 4 channel .mod (the ripoff is from a playback using the C64 SID soundchip). The song was hosted on scene.org's servers (the main repository for all everyones demos and tracked music, etc.). As you might expect, no permission or royalties were paid to Tempest. Just to clarify, we're not talking about some kind of coincidence here. There is no question that this track was used to create the song "Do It". In an interview, Timbaland tries to downplay it, saying things like "he sampled it from a video game". (This track was not written for a video game- it was actually written for the 2000 demoscene music competition, in which it won 1st place). Regardless, he basically claims he has no legal obligations because it's just like all the other pop artists that sample other m

Reaper, Linux, and the Behringer X-Air - Complete Studio Solution, Part 1

Introduction and Rationale This is part one of a major effort to document my experiences with recreating my home studio, entirely using Linux.  Without getting into too many of the specifics, a few months ago I decided that I was unhappy with Windows' shenanigans - to the point that I was ready to make a serious attempt to leave it behind.  For most in this situation, the obvious choice is to switch to Mac OS.  With its proven track record, support, and options for multimedia production, it is naturally the first alternative to consider if your goal is to simply use something other than Windows. For me the choice was not so simple. I despise Mac OS and, in general, the goals and philosophies put forth by Apple in an effort to ostensibly provide users with an "easy" working environment.  It does not help that I have also failed to find any aspect of the Mac OS UI intuitive, but I realize that this is a subjective matter. With my IT background and user-control* favori

Windows 8 audio clicks and glitches narrowed down to Malwarebytes

Ever since I got my Windows 8 PC, I have been having serious problems with audio.  Basically all sound playback on my system experiences a brief  but frequent click, skip, glitch, stutter, whatever you prefer.  I can reproduce the issue on any sound card or firewire sound interface (devices tested include the onboard Conexant SmartAudio HD, my external Phonic Helix 12, and my Edirol FA-101).  All of them seem to have audio clicks, with the firewire interfaces' clicks seeming more harsh for whatever reason.