Andrew Morris was frustrated by the inadequate thermostats on most space heaters. The thermostat is typically built inside the heater and has little contact with the outside world. It switches on and off according to the temperature inside the heater, not the ambient air temperature. This makes it little more than a duty-cycle controller, similar to the nonthermostatic control on an electric stove or the temperature control on an electric blanket.
Morris decided to design an electronic thermostat that senses the actual room temperature. He tested and tweaked it to get the proper control range and hysteresis. The new thermostat has an internal adjustment to set the center temperature. It has a range of 20F, centered at 70F. In creating the new thermostat, he did not alter any of the safety functions in the heater.
Wall mounting is more convenient to use and gets a better sense of the room temperature.
Andrew Morris' gadget saves electricity by using the actual room temperature to control the heater.
I know it's out of season right now, but winter will get here before you know it. I built three of these thermostats last December and they served me quite well. I have received numerous requests from friends and family to build some units for them. They are great for a hobbyist, but they are too labor-intensive to build and sell without printed circuit boards. They're otherwise pretty cheap to make. I used the shells of the three remote controls I hacked up to make two volume controls (GF #192) and a fan control (GF #198). Now, I'll have to buy enclosures and outlets for the power units of any more thermostats I might make. The remote control enclosures were perfect for the job. You can probably buy a remote control at a flea market or a garage sale that has lost its transmitter or doesn't work. Or you could just build one of my remote control gadgets and use the shell from the hacked remote.
Andrew, thank you for coming up with this design. In our case, mountain winters can be especially cold in a sort-of-insulated cabin on stilts, so our thermostat problems are keeping the space heater downstairs on for a longer time at a given heat output.
Given the heat around the country this summer, winter can't come too soon. I never thought I'd say that. This thermostat is a great idea. You identified a real need, Andrew. The thermostats on space heaters are useless.
I agree with you that it is surprising that manufacturers did not think of this. It's such an inexpensive solution to a problem that should have been noticed.
You know what would be cool? Imagine an option where a ZigBee enabled the thermostat to be mounted across the room -- anywhere in the room so that we get to enjoy a more average temperature from the heater. Yeah, that's not as simple and elegant, but it might be an add on.
Well done Andrew with this gadget - once again you've managed to put together a really impressive gadget that is useful in improving power utilization and control of the heater operation. But putting the thermostat controller in the ambient temperature zone, the feedback between the environment and heating element is improved considerably, giving more comfort and control to the user. Impressive!
I had a similar issue with the built-in thermostat on my 5000W Fahrenheat Ceiling-Mount heater when I installed it in my garage. It was pretty easy to add a relay and a standard wall-mount thermostat to get better control over the temperature. A good alternative if you don't want to build a gadget.
Controlling the heater by sensing the actual room temperature is a definite advantage. I plan to do it this winter by using a regular old household thermostat and a relay, either mechanical or solid state.
Not to burst anyone's bubble, but these have been on the market for at least 15 years.
I buy mine from Northern Tool. They are digital. You can get 120V or 240V single phase rated units. They even have a digital readout with the target and actual temp readings. They plug directly into a wall socket and fit flush with the wall socket. Then the heater cord plugs into it.
It's always fun to build things you can call your own. However, ALL electrical appliances must comply with UL. If something were to happen to this home made thermostat and caused a fire you could be held liable! The Insurance Company could try to make you a criminal.
I think I paid $50.00 for mine at Northern. I think Amazon sells them for even less!
In our third annual contest, Design News and Allied Electronics are going to crown a winner in early 2016 for the best reader gadget submission this year, and once again, you, the readers, are the judges!
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