Over-the-side heater is not a very commonly used heater, but it has its advantage. It is the most appropriate heater for chemical compounds such as wax. Wax has low viscosity rating, melting at 44⁰C, and requires the heat spread evenly throughout the tank. The tanks for containing wax usually have a small hole on top, so over-the-side heater can slide into the nicely without any structural modification to the tank. These heaters are most often economic and practical as compared to other heaters because they are simpler in construction.

WATTCO™ over-the-side heaters are typically custom designed, shaped to fit in either standard or non-standard tanks, having multiple tubular elements and a thermowell to hold the temperature probe. Over-the-side heaters are usually installed through the top portion of the tank hanging in on the side of the liquid to be heated. The most important aspect of wax heating is the temperature control. Too much heat will burn and destroy wax; for example, organic soy wax will be ruined at 140⁰F (60⁰C), and should never be heated above 200⁰F (93⁰C).

Conventionally, there are two types of tank for wax heating: direct heat and water jacket. The direct heat tanks are generally made out of aluminum and can heat up to 500⁰F (260⁰C). These tanks apply heat directly to wax, and is often used for melting wax. For that reason, the tanks are very small with capacity of 5 to 10 gallons. On the other hand, water jacket tanks are much larger in size with up to 1,000 gallons or more. It functions like a large commercial double boiler in that the tank contents are evenly heated. Since the water would evaporate, it can generally heat only up to 212⁰F (100⁰C).

WATTCO™ over-the-side heaters have advantages over the conventional tanks in that the heaters can be simply installed over the top opening and keep the low heat spread throughout evenly. It is cost efficient in many ways because it doesn’t require a sophisticated digital controller since the temperature variance is minimal. A thermostat is sufficient to control the temperature. The heaters can be low watt density allowing for a long lasting operation, and can also avoid any wax deposits from forming.

Wax heating environment is particularly vulnerable to fumes. Electric immersion heaters can help alleviate the problem by limiting the overheating as well as preventing evaporation or drainage. There are several applications for which the over-the-side heaters can be used, such as heating oils of various viscosity, degreasing solution, heat transfer oils, and caustic solutions.

WATTCO™ uses various special alloys such as steel, copper, cast alloy, or titanium, for heating elements, which can physically withstand harsh environments both indoors and outdoors to construct the over-the-side heater. The approach of the over-the-sire heater is that the substance it is heating sits usually below the heater or onto the side of the heater. The advantage is that there are ample space in the tank for to work with, and the heater is also easily removable when necessary.