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Hot Box; my Summer project

post #1 of 13
Thread Starter 
I plan on building a Hot Box over the summer. I have a couple questions for anybody who has built one or anyone really.
1) I am thinking about using dimmer switches on my light bulbs to help regulate the temperature. Any possible problems with this?

2) I have a small computer fan I'd like to put inside the box to help circulate the air. I will be using a wall mount power supply to get the 12VDC i need. Does anybody see a problem putting this fan inside the box?
Thanks
post #2 of 13
I built one two summers ago. I used a portable heater, took it apart and installed it in the box. I has its own thermostat.

Fan should be fine.
post #3 of 13
Quote:
Originally Posted by fishEH View Post
I plan on building a Hot Box over the summer. I have a couple questions for anybody who has built one or anyone really.
1) I am thinking about using dimmer switches on my light bulbs to help regulate the temperature. Any possible problems with this?
I don't think you'll be dimming it down too much.


Quote:
2) I have a small computer fan I'd like to put inside the box to help circulate the air. I will be using a wall mount power supply to get the 12VDC i need. Does anybody see a problem putting this fan inside the box?
Thanks

That seems inefficient (cord and transformer loss). Radio Shack sell muffin fans for 120VAC. Split it off the main heater supply.

I also don't think you need a fan, or to circulate the air. If the bulbs are doing their job, then the skis will be hotter than the air by radiant absorption. The only thing the fan can do then is cool the skis off and stir up airborne dust that may have settled to the bottom of the box.

How about building it with just the bulbs and internal reflective surfaces, putting a temp probe on the ski bases, then using the dimmer just to make sure the skis themselves don't exceed 180F.
post #4 of 13
I've been playing around with various hot box designs for a few months & using a temperature probe I found that a light bulb design (5 lamps) without a fan gave too wide a variance of temperature within the box, 19-23F degrees variance in fact. Using a fan dropped this to 10-12F degress variance which for me was still inacceptable. In both cases, not surprisingly, the hottest areas were directly below the lamp.

Because of the high 'spot' heat I disgarded the lamp design & looked at a heater & fan set-up. A very good set-up would be a tubular heater with a seperate fan & a thermostat etc. My box has internal dims of 200x35x45cm (it takes two pairs of skis) which would require approx 300 watts of heat to maintain it at approx 70C/160F which can easily be obtained by installing a 4' 80wpf tubular heater. These are the types of heaters used in greenhouses etc so can easily be obtained from a local gardening store, although the quality isn't usually that great & the thermostats often won't measure at high enough temperatures. A better option would be a commerical quality tubular heater, fan & a thermostat from the likes of Watlow US which you should be albe to get for $100-$150 as the same solution from Watlow UK was about £80.

For the ultimate solution contact Mike at http://raceeffect.com. Mike (who is Indy GS on this forum) is now starting to offer for sale a scaled downed version of the heater/blower/control unit that he installs in his superb commercial hot boxes to give DIY box builders a commercial quality system. This is the solution I've gone for & the unit arrived just a few days ago. I haven't had a chance to install it yet but I've re-wired the control unit for UK 240V (it's either 110V or 240V depending on the internal wiring terminals selected) & fired it up on the bench & everything works superbly. Will post again with pics when it's installed & tested etc.
post #5 of 13
My box build: http://forums.epicski.com/showthread...ghlight=hotbox

I used an el-cheapo Lakewood portable heater. I could have used a better heater but I didnt see the need to spend more $$.
post #6 of 13
Quote:
Originally Posted by Richie-Rich View Post
My box build: http://forums.epicski.com/showthread...ghlight=hotbox

I used an el-cheapo Lakewood portable heater. I could have used a better heater but I didnt see the need to spend more $$.
Let me guess. It is this years model and it is BIGGER than the neighbors hot box. :
post #7 of 13
Installed the fan/heater unit this afternoon which required a bit of jigsawing as it protrudes through the base of the box. Just got to make a mounting bracket for the control unit to fit to the end of the box in a position so that the readout can be easily seen then I can wire up & I'll be good to go.
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post #8 of 13
Thread Starter 
Quote:
Originally Posted by Richie-Rich View Post
My box build: http://forums.epicski.com/showthread...ghlight=hotbox

I used an el-cheapo Lakewood portable heater. I could have used a better heater but I didnt see the need to spend more $$.
Thanks for the link Richie Rich. Does the Lakewood heater give pretty consistent temperatures? I'd like to use a heater like that instead of light bulbs for the sake of simplicity and space. What is the max temp you can get your box up to? I've looked at some space heaters and some have an overtemp. shut off. Can you tell me what model heater you're using?
post #9 of 13
fishEH, the one I used was the MODEL 792/JR
There are probably better options but its what I found that was suitable. Using a metal cutting disk I cut the actual control panel out and bolted it to the outside of my hot box. I later added a diffuser in front of the heater element and fan to better distribute the heat coming from the unit. I discarded the heaters enclosure. The heat is pretty stable but I think adding an addition fan to help circulate the hot air better might be beneficial.
post #10 of 13
spyderjon...... how are you going to fit my DH boards in your 2m box
post #11 of 13
Quote:
Originally Posted by CEM View Post
spyderjon...... how are you going to fit my DH boards in your 2m box
No problem matey, I have a cunning plan
post #12 of 13
no cutting the skis down is not the answer!!!!, but i am sure you will build a little annex to the box just for this type of situation
post #13 of 13
Quote:
Originally Posted by CEM View Post
......but i am sure you will build a little annex to the box just for this type of situation
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