Fan Dickinson Newport Heater blows breaker

[KrazySailing]

Hi

I've a recent problem with my Dickenson Newport diesel heater's fan. Every few hours it blows the breaker. I am wondering what is the source of the problem.

I have an aluminum hulled sailboat. I bought the stove used and do not know how many hours it has been used, but it does look in good shape. The fan is 12V. The positive and negative sides of the circuits are fused and switched separately at the main 12V electrical panel. The 12/2 wire run is about 8 feet to the heater. The boat needs a rebuild inside and I've set-up temporary wiring and panels. The 12V positive is switched from a 12V tap with an on/off switch, then a 1/2 A fuse and then the wire run to the heater. The negative side of the circuit is run from a Vetus P12 breaker panel. The P12 has built in 10A breakers. This is the breaker that blows. There are quick disconnects for + and - circuits at the heater. There is no 120V AC circuitry on the boat.

Your advice?

Thanks

[Dsanduril]

If there is only the fan on the circuit described then the problem pretty much has to be the breaker. If you are tripping a 10A breaker while leaving a 1/2A fuse intact on the same circuit then the breaker is faulty.

Only other option, you have some form of ground loop where other equipment is using that portion of the negative wiring, the heater, and the metal hull to go to ground in a way you don't intend. Only way I can see where 1/2A on the positive side stays whole and negative side carries >10A.

[um saudade]

The factory boost fan draws less than a ¼ amp if working correctly.

First determine the actual draw on the fan using a fused jumper setup and ammeter.

If the fan draw is correct then something is cross wired and you are feeding multiple devices with the circuit breakers, or at least the negative side of the circuit.

[7623]

As the 1/2A fuse on the pos side doesn't trip, the problem will be in the neg circuit. If there was a problem with the fan your 1/2A fuse would go first.

Could be a faulty breaker? You are running something else on the P12 breaker?
See if you can measure current at P12, that would be interesting.

[KrazySailing]

Update:

I'll try your suggestions.

It is looking like the West Marine 30 amp Smart Charger (on 2 type 27 batteries) is the cause. A couple of times when it has charged the battery to full and then started charging at 2 amps later or at some other stage it has blown the breaker on the negative side of the circuit.

Thx