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Will this work?

Started by woodman58, June 19, 2010, 01:24:58 PM

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woodman58

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I've got my refrigerated kiln box up and running. For now I am using House dehimidifier. My Question is how many dehumidifiers should I use. I have a 1000 BF load of mixed wood in now, I have 2 fans, and 1 dehumidifier. My problem is only I only have one outlet (150ft of 10 gauge extention cord on 15 amp circuit) that I can use until I can get power to the kiln. For now will this work? Thanks
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Kcwoodbutcher

It depends on how big the dehumidifier is.  The normal house size is 24 pints per day running flat out.  That's close to the right size for  a 1000 foot load. A little bigger would be better but two would be too big at the beginning of the run unless you slowed down the cycle. It may take just a little bit longer but I'd just stay with the one for now. I think you could get by running two from the electrical setup you have. The home dehumidifiers don't draw that much current, but just look at the label to be sure.
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ladylake

 I don't think household dehumidifiers draw a lot of amps, you could  try running 2 if needed, if the cord gets to hot or blows the breaker go back to 1. I like to dry my lumber slow, air dry at first then kiln it.   Steve
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r.man

Woodman, add up the amps for the humidifiers and whatever else is on the extension cord or add the watts and divide by 120. Is the circuit powered by a breaker or a fuse? With a breaker you can probably load the circuit to 12 or 13 amps without any problem, the same with the fuse except start up might blow the fuse. In our jurisdiction it is considered safe to increase one fuse size for a motor load.( it's legal as well) You're probably ok unless both compressors try to start at once.
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PineNut

Unfortunately this is not a simple answer. There are several things to consider.

1.   #10 wire can handle up to 30 amps (per NEC). This does not consider voltage drop over a long run of wire.

2.   At 120 volts, the maximum distance using #10 wire, 2% voltage drop at 5 amps is 150 ft. (per ITT Reference Data for Radio Engineers)

I checked a dehumidifier and the operating current for a 40-pint unit is 5.1 amps. This unit is rated at 115 VAC (not 120 which is the usual voltage). My no load voltage is about 123 volts. If you have a solid 120-volt supply under load, and your dehumidifiers are rated at 115 volts, you should have no problems with 2 of them on a 150 ft line of #10. However if you are connecting to a 15-amp circuit, you may have a run of #14 wire feeding that circuit and that will contribute to the voltage drop. (Then all bets are off.)

Probably the easiest way would be to connect one dehumidifier to the end of the #10 wire and measure the voltage at the dehumidifier while the unit is operating. If the voltage is at or above the nameplate voltage, you should be OK. If it is too low, it will be putting a strain on the dehumidifier, which may not give any problems but then could result in a shortened life for the dehumidifier. If voltage is not too low, then you could then try the second unit.   


pineywoods

I've been using room de-humidifiers in my kiln for a few years. It's a cheap way to make a fairly nice kiln. You need to be aware of a couple of things. 1 If you dry a lot of hardwood, particularly oak, the acid will eventually corrode the aluminum parts. 2 the DH unit will add a fair amount of heat to the air in the kiln enclosure. This may or may not be desirable.
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