Electrically Heated Oil in Molds Produces Uniform Imitation Stone

Circulation Heater

The Challenge
For consistent production of imitation landscaping stones, their molds must be heated uniformly.

The Solution
A hot oil circulation method was determined to be the best for the operation, considering the uniformity needed. The hot oil (275° F) is circulated continuously through the molds while each press is in operation.

The heat source is one Chromalox Electric Circulation Heater, Type NWHO-3901, 9 kW, 230 volts, at each press. This was considered to be the most compact heating package and by far the easiest to install and use.

Oil is continuously pumped through the heaters and molds. A thermostat in each heater maintains oil temperature constantly at 275° F.

Results: A high-quality product from each operation of each press. Rejects: None.


  • It provides a constant heat source for getting the most out of the circulated hot oil system.
  • It is completely safe and eliminates rejects.
  • Heater investment and installation costs were small.
  • All heat goes into the work - providing an efficient, economical use of energy.
  • It provides a fully compact and integrated operation dependent on nothing but electrical energy. One press, several, or all can be used as needed. Warm-up period is brief.
  • There is no heat source maintenance problem or expense.