heat box plans?

[duffontap]

You've got a good point Matt.  My heat box stays in my insulated shop so I never have to mess with it.  In my case, the dimmer switch I had on hand works great, but a thermostat that was trustworthy would be really nice.  The reason why I didn't use one was household furnace thermostats don't go high enough, and other thermostats have such a range I worry that they won't keep my box within the 5 degree range I want it at.  I have a thermometer in the box at the level of the bows so I can make sure I'm getting the temp I like.  I'm always open to improvements though. 

          J. D. Duff

[Justin Snyder]

JD, there is no doubt that the new dimmer is more efficient than the old.  But lets not forget there is energy lost every time a switch is flipped, energy to run the switch. It produces heat in the switch just like in the bulb. In not suggesting the new dimmer with a 60W bulb is not more efficient than a 60W left on.  But a 30W will still be more efficient.

According to Advanced Technologies, who does the actual testing, there is some misleading info on dimmers.  The bulb is not actually turned off. The dimmer switching on and off just decreases the height of the sine wave, decreasing the power to the bulb. Because a bulb or appliance is not being supplied with the correct amount of power when it is on, it decreases the life of the bulb or appliance. Inefficient use does not necessarily relate to net savings. Example, if a fan is switched to medium, it requires less energy in 1/2 hour than if left on high. However the fan left on high can run 1/2 the time to cool the room, thus using less energy. I think the thermostat is the best option by far.  I know I'm a bit anal.  I am getting ready to start building my new "Green" home. A little up $ front can save huge later on. Might even pay for a caribou hunt.

Pappy, I would recommend a box outside anyway. Even if your wife don't mind the huge new piece of furnature.  A box inside the house heating to 100* can sure add to the cooling bill. Just make sure your fan is wired on a seperate switch. It would be silly to reduce the air flow, since constant air flow is what the fan was added for anyway. Justin

[MattE]

I don't see any pronlem with the dimmer switch method but if you use four or more bulbs of high wattage it will build up resistance and could catch fire.If you opt for a thermostat and incorporate a minature fan to keep the air flowing you will have accurate temps plus eliminate the possibility of resistance on the system and the chance of a fire.

[welch2]

Justin , I think you are both partly right. I've worked in electronics my whole life. you are right in that a dimmer 'cuts the sine wave' this reduces voltage. And it is detrimental to most devices. But a light bulb is just a piece of wire in a vacuum . You run current though this wire till it gets hot enough to emit photons (light). works like a feather burner.
   So here is where JD is right, in the heat box you don't care if the the bulbs light up dim or bright , you just want it's heat.The light in this case is wasted energy. JD's dimmer method will extend the life of the bulbs , because at lower voltages they don't get hot enough to burn the elements in two. Notice that light bulbs are not only rated by wattage , they also have a voltage rating. In a given light fixture the same wattage bulb with a higher voltage rating will last longer.
   But the dimmer does distort the waveform , and depending on the quality of the dimmer could have several switching spikes or other anomalies to the waveform that shorten the bulb life some.  Better than a dimmer ,find an old autotransformer or variac, these are adjustable transformers that allow you to adjust the line voltage up and down.
   So I think a thermostat ,even a fixed one like Binghams sells, is the most efficient on your power bill, but  a dimmer or a variac will make the bulbs last longer .Combining the two may be the best bet.

Ralph

[Justin Snyder]

Hey JD, I have a thermostat that has a 1/10 degree variance.  Its not really cost effective for a hot box at $70.  Justin

[duffontap]

Thanks so much for the info Ralph.

Here's where I'm at on this.  I posted the suggestion of the dimmer switch because it has lowered my energy consumption and greatly extended my bulb life.  I guess I'm just willing to squander the amount of electricity needed to power a dimmer switch.    My system isn't perfect but it beats controlling the temp. by venting (my old system) and I get to use the ultra-cheap 60 wt. bulbs I have in the pantry. 

Secondly, controlling the temp. by using lower-wattage bulbs has its down sides as well.  If you have to run lower-wattage bulbs at full power you may be getting less life out of more expensive bulbs, and have to let heat escape your box to control the temperature. 

Thirdly, while I totally agree that an accurate thermostat would be the way to go, I think my simple system gets me 90% of the way there and it's done.  I'm slightly suspicious that the $50 thermostat (plus S & H) from Bingham Projects would pay for itself in energy savings after about 400 years. 

Lastly, for many of us the object is to avoid any unnecessary expense.  I built my hot box out of construction debris I scrounged so it fit within my anual archery budget of approximately 5 bucks.  These drying boxes can be totally safe and respectably efficient without foil backed insulation and expensive fixtures, bulbs and thermostats and for some people it's worth the trade-offs of not having the 'ultimate' system that Bingham projects sells plans for. 

Justin--1/10 of a degree isn't good enough!!!!!!   
 
          J. D. 

[MattE]

J.D. I just happen to have an extra thermostat if you want it is yours!
 I will have to find it, I cleaned up my shop and now I am lost along with the thermostat!
  It is out of a hot water heater.