Water Cooled Power Resistors

[tubeswell]

Hold the toast down with the butter knife normally used to pry them up.

And then when you're done, makes a handy warm knife for your butter on those cold scottish winters

[jmaf]

I drove to the local Carrefour and bought 6 x 3500Watt replacement shower resistances for a few bucks each. Took them apart, stretched them into a pine box and have taps for 2,4 8 and 16 ohms. Whenever they get warm, I'll just put the box in front of my bench fan. Of course they're made to work in water, so the water or oil ideas probably work a dandy, though I don't normally keep any water near my bench for evident reasons.

[R.G.]

Note that water and oil for submerging resistances does not need to be in an open container. The fluids are merely heat spreaders and thermal integrators for adding mass. The old radio "Cantennas" were sealed buckets to be filled with water. I don't know how "shower resistances" mount, but if they're like water heater elements, they come on a circular threaded plug assembly which is meant to be inserted into the wall of a water tank. If you had a metal bucket with a metal cover, like some paints come in, you could drill holes in the lid, mount the elements, fill the bucket, then put the lid on the bucket semi-permanently. No *exposed* water near your bench.

[Chuck H]

A couple of items from personal experience...

I live on an island. Most of the homes are on wells. As with many islands there is some degree of salination and a problem with water hardness. There are no gas lines on most islands either so unless you run your water heater and dryer off your propane tank you use electric appliances. Being a pretty handy guy in a smallish town I get called into service for friends and relatives. A lot.

Water heater elements only last about six months in our local water. At that point they become so caked with deposits that they short out. Not sure why but I've guessed that it's the lack of direct water contact convecting heat away from the element itself. It's worth noting that water heaters have new water with more minerals being introduced during use. So the water hardness issue may not be as much of a problem in a sealed tank but I would use distilled water anyway.

Also, most water heaters are about fourty gallons and the electric ones typically use two elements. So that's one element for twenty gallons of water. These devices are also on thermostats that regulate the water temperature to between 160*F and 180*F. I'm sure there's some engineering formula having to do with mass and the specific gravity of water, etc. My point is that in a five gallon bucket I don't think you can expect the same dissapation factor. Not that it should be a problem for most amp jobs with a 1500 watt element. You could put a thermometer in the tank to moniter the water temp and just take a break for a while when the water reaches 175*F. Not quite hot enough for a cup of tea though.