Results of tests on the amounts of electrical energy needed to keep water ice-free in automatic stock waterers furnish some tips on how to keep operating costs down whether your waterer uses electricity or some other fuel.
Calderwood, David L. and Altman, Landy B.
"Cutting Operating Costs for Automatic Stock Waterers,"
Iowa Farm Science: Vol. 8
, Article 2.
Available at: https://lib.dr.iastate.edu/farmscience/vol8/iss4/2