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Old 03-02-2019, 11:26 AM   #15
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City: Watch Hill RI
Vessel Name: Puffin
Vessel Model: Nordic Tug 32/34
Join Date: Jan 2008
Posts: 142
The air or "grid heater" is either a box heater just before the turbo air intake, or in my case with a jacket water after cooler (JWAC) 6BTA, located under the JWAC. After I start the engine, I'll push up to 1,000 RPM for the few minutes it takes to warm the air intake. At that RPM, there's usually enough voltage coming off the alternator to keep the voltage from cycling.

The electrical components on these grid heaters are a problem. The ECM and contactors can fail (mine shorted out last season), and replacement components are about $500. I'll be removing all ECM components and install a fused push button momentary ON/OFF switch on the console, and wire directly to the grid heater terminals.

There is a temperature actuator in the components (58 degrees sounds right), and unless it's really cold, the engine will start without a pre-heating cycle. I have a block heater on my 6BTA and that's enough to start the engine in cold weather without a pre-heater (assumes you're plugged into shore power). Tony Athens of Seaboard recommends removing air and block heaters (problematic), and use an external oil pan heater if your operating in cold temperatures.
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