DIsclaimer: I am not an engineer or electrician to be considered=20
competent in this area, but have worked a lot with my home heating system.

  What I think you are wanting to do, is switch a normal duplex 120 volt=20
say 20 amp outlet, that the equipment will be plugged into. The heater=20
itself is UL labeled and has a tip over switch. The heater has it's own=20
thermostat that could be set higher than normal set temperatures to be=20
always on, but low enough to turn the heater off before getting hot=20
enough to cause a dangerous situation. Line voltage thermostats are=20
readily available, and should be mounted not on an outside wall, and not=20
in a drafty area. Your problem of wide temperature swings could be more=20
due to  thermostat location than anything else. A standard electronic=20
thermostat could be used, some of them you can set the dead band, but=20
they out of the box do a good job. You would need a 24 VAC power supply,=20
a door bell transformer would easily handle the load.  The thermostat=20
generally will have a set of dry (mechanical) relay contacts. The=20
thermostat will need the following wiring: 1 leg of 24 VAC to "B"=20
terminal, other leg to "R" terminal, "W" terminal to coil of relay. An=20
appropriately rated contacts relay with 24 VAC coil, the other coil=20
terminal to the "B" leg of the 24 VAC. A KUP family of relay should work=20
nicely.

But, a PIC could easily be set up as a thermostat. An analog, or I2C=20
sensor would probably be easiest, with an output going to a 2n2222=20
transistor driver to a relay. I would be conservative on sizing the=20
relay contacts for the line voltage load. The relay would as described=20
above switch the outlet, and the heated has it's safeties.

It is important to do things in accordance with the building codes. Some=20
insurance claims  have not been paid due to non-code compliance. I would=20
put line voltage relay in a metal enclosure.
On 12/19/13 7:23 PM, Jason White wrote:
> Hello, recently I have had my home work space moved from a nice heated
> room into an unfinished basement. The area is nominally 55 degrees F
> however an area has been partitioned of so that a cheap plug in
> 1500/750 watt heater can easily raise it to an excess of 80 degrees F.
> So far I have found it difficult to reach an equilibrium between
> allowing cold air in and heating the room so I am looking to build a
> controller. I have looked at using a normal thermostat to switch
> relays, however the one I have access to reacts too slowly to
> temperature changes of a small room to be of use. As a result I am
> considering build a custom thermostat (likely PIC based) in which I
> can tweak the sensitivity to my liking.
>
> I am in the US. I plan on putting the controlling logic in a plastic
> wall mountable enclosure and then running wires to energize a free
> hanging relay placed inside and wired inline with a normal outlet.
> Does anyone know of if there are any restrictions on this sort of
> setup safety/electrical code wise? Any tips on doing this
> better/safer?
>
> Thanks,
> Jason White
>
> *One additional note, yes I would like to roll my own solution.
> Although suggestions for better alternatives are welcome.

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