shopping for DH

[xlogger]

There are several on craigslist for sale but I find out most or all that I've email don't get back to you. But I have a question on them. About what amps do they pull? I've got a long run from the house and have to watch my load. Later I plan on running a heavier wire about 1/2 to the kiln where I have a spit to mill and woodstove and put in a new box there but for now I don't have that.
Also being new at this will the DH run at what low temp? Would I need it to run in winter time also?

[GeneWengert-WoodDoc]

A basement, home dehumidifier current draw depends on its size.  For example, one rated at 30 pints a day draws 4.8 amps, 50 pints is 6.6 and 70 pints is 7.5 amps.

It will run in a basement as low as 41 F before the coils freeze.  This is variable depending on the humidity, however.  Many commercial DH units require 85 F to provide good lubrication and prevent freezing.  Therefore, a DH kiln needs auxiliary heat at the beginning to get the kiln hot enough.  Once the compressor starts (in a well insulated building) no further heat is needed in most situations.

The life of a small DH unit depends on the lubrication of the compressor.  Used units can be questionable.  This short life is why Home Depot sells a new unit with a supplemental replacement warrantee for 35% of the cost of the unit...life is short in many cases.  Part of the issue is that the new refrigeration gases used do not lubricate as well as freon did, but the old freon gases depleted the ozone, so we had to switch.

[kelLOGg]

The life of a small DH unit depends on the lubrication of the compressor.  Used units can be questionable.  This short life is why Home Depot sells a new unit with a supplemental replacement warrantee for 35% of the cost of the unit...life is short in many cases.  Part of the issue is that the new refrigeration gases used do not lubricate as well as freon did, but the old freon gases depleted the ozone, so we had to switch.

Gene, what account for the longevity and high temperature capability of commercial DH units such as Nyle? Aren't they beholden to the new refrigeration gasses?
Bob

[GeneWengert-WoodDoc]

Different gasses   Often a gas loses its lubrication at hotter temperatures too.

[YellowHammer]

what account for the longevity and high temperature capability of commercial DH units such as Nyle? Aren't they beholden to the new refrigeration gasses?
Bob

They try to be, up to a point.  However, many things must be considered when selecting a proper refrigerant for the application.  Look up the DuPont Refrigeration Cross Refernce web page to see the different properties and uses of specific refrigerant.  Home dehumidifier units are expected to function under a different set of environmental parameters (such as a house staying at about 70F) year round as opposed to a kiln which operates under much more extreme temperatures, so different refrigerants are recommended. Interestingly enough, both the refrigerants used in my two Nyle kilns, different models, different OEM refrigerants, cross reference to automotive air conditioning refridgerants.

I've used several home dehumidifiers in my solar kiln, and my experience is that they generally fail due to corrosion of the fan blower or the electronics, or develop pin holes in the refrigeration system.   I haven't lost one to a compressor motor failure, specifically, but nonetheless, they fail one way or the other, in a couple years. 

[pineywoods]

My experience with home dh units matches Yellowhammer's. They don't work well at high temps, better to turn them off during high temp periods. Most of them have an automatic high temp shutoff anyway. They are definitely not long life boxes, but are cheap. We buy used ones at flea markets and auctions for $10-$20 and just replace them when they fail..Work real well inside a solar kiln..

[GeneWengert-WoodDoc]

Home units are noted for over-heating and creating a fire hazard, so at the least, include a smoke alarm.  The better DH units have a thermal overheat shut off.

If this is in a home, make sure that a business operation will not cancel your household fire insurance.