Are you taking advantage of a new heater technology to improve your business and keep your customers’ koi and other fish alive this winter?
Until now aquaculture immersion heaters have used an internal resistance wire as the heat source. Now there are electric immersion heaters available using PTC (Positive Temperature Coefficient) ceramic chips as the heat source. Heaters using PTC offer advantages over traditional resistance heaters including increased safety, greater reliability, and a lower operating cost.
**Electric heaters made with resistance wire:**
Traditional immersion heaters use “resistance wire” as the source of heat. Resistance wire is commonly used in toasters and electric water heaters and is usually a nickel/chromium alloy. It will typically heat to around 900°F.
When an electric immersion heater using resistance wire operates in air or becomes covered with solid buildup (such as fish waste), the heat is not able to dissipate quickly enough. This results in a rapid increase in operating temperature. Elevated temperatures shorten the heater life and can damage surrounding plastic materials including pond liners.
To protect these materials from high-temperature damage, electric immersion heaters often include a built-in heater over-temperature cutoff device – called a “protector.” The protector senses the surface temperature of the heater and trips if it gets too hot. This shuts the heater off. While the protector is a necessary safety device, a heater that is shut off may threaten the pond or tank inhabitants.
As Don Campbell, First Ascent Fish Farm, explains, this is one of his primary concerns with his current equipment. *“We train our customers in both programming and care of the heater/controller. However, too frequently the folks we train are not the folks cleaning the tanks between deliveries and the heater is not unplugged, leading to a blown fuse [protector].*”
After a protector has tripped it must be replaced. If there is no protector onsite, the tank or pond may suffer a loss of heat. For a supplier or keeper of live fish, this can result in increased mortality.
**Electric heaters made with PTC chips:**
Electric heaters using PTC chips do not use resistance wire as a source of heat. Instead, they use PTC (**P**ositive **T**emperature **C**oefficient) chips. When the chip temperature increases, its electrical resistance also increases, resulting in decreased heat output. As the PTC chips heat up, they will reach a designed temperature at which they cannot get any hotter. Thus, PTC chips have a predetermined temperature limit.
**No protectors to replace.**
Thermal protectors are not necessary with PTC electric immersion heaters. Their self-limiting capability offers the safety of a protector built directly into the heater core. This eliminates downtime caused by a tripped protector and the need for replacements.
**PTC heaters will not damage tanks or liners.**
PTC immersion heaters have a maximum surface temperature of 518°F when in air and manufactured with ½-inch spacers so they will not damage tank or pond liner materials. They will not damage tanks made from polyethylene (PE), high-density polyethylene (HDPE), fiberglass, polypropylene (PP), CPVC or PVC as well as other materials (see chart).
**PTC heaters can operate in air or with solids buildup.**
A resistance heater will overheat if operated in air, covered by scale or solid waste. This elevated temperature can shorten the life of the heater by several months. With PTC heaters the potential for burnout is eliminated, thereby increasing service life. (Removing the material from the surface of the PTC heater or putting it back in water will raise the heat output accordingly.)
According to Campbell, the advantages offered by PTC heaters, *“could pay for themselves in both labor savings and fewer mortalities in less than one year.”*