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Cabin Heater

Our boat is a 2002 Duffy 18' Classic. Many systems and components are common across models and years.
It is up to you to determine if this information applies to your boat or not.

Overview

The heater system may be hazardous. Here are the risks to check for:

1. In-line fuses for the 36V heating elements on our boat were improperly sized, allowing too much current to be drawn and wiring to burn. These fuses are located near each heater's wiring connections.
2. 36V wiring from the batteries to the contactor should also have a properly sized in-line fuse at the battery connection.
3. A single 12V contactor switches the +36V supply to both heaters. It is not designed or rated to switch the heaters on, but if a heater mode switch is left on "heat" when the key switch is turned on, the 12V contactor would be switching 36V of high current. For this reason, it is important to ensure that heater toggle switches are in the "off" mode before turning the key switch on.

The heater has separate in-line fuses for the fan and heater power supplies. The heater also has two temperature activated switches. One acts as a thermostat, opening and closing power to the heating element at a set temperature (140F). The other acts as an over-temperature switch that will turn off the heater element if the internal air temperature reaches 160F. There is a manual reset button on the over-temperature switch.

Contactor

The contactor is located in the Starboard battery compartment. When the key switch is turned on, you should hear the contactor close (a loud "clack"). When the key switch is turned off, you should hear the contactor open to its default power off, normally open, state.

Our part is a White-Rodgers 120-105111 coil 12V DC contactor (Specifications PDF)

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