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  #1  
Old 12-15-2012
Strayhound Strayhound is offline
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Default Low voltage at bedroom furnace thermostat

The bedroom thermostat is drawing only 2 volts. The two forward thermostats are at 12 volts. The bedroom thermostat line was spliced and 12 volt inline to the Dometic RM2820, which suddenly lost all power and quit working.

The wiring diagram shows all three thermostats connected to the same line.

Why would the voltage drop from the forward thermostats as it goes to the rear thermostat?

Is it correct to simply splice the thermostat line to supply 12 volt to the Dometic?

Or should the 12volt line to the Dometic come directly off the battery with an inline fuse?

Thanks for any suggestions!
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  #2  
Old 12-15-2012
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I'm assuming heater T-stats?
Suburban brand?
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  #3  
Old 12-15-2012
Strayhound Strayhound is offline
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There's 12 volts to the rear heater, but the hot from the heater to the thermostat is only showing between 1 and 2 volts.

It's a Suburban heater.

Meanwhile, the 12 V line to the Dometic 2820 was spliced into the hot from the heater to the thermostat. I'm assuming when the 12 volts suddenly dropped, the power to the Dometic was cut.

I'm now planning to run a single 12V line from the battery directly to the Dometic. Do i need an inline fuse or will the control panel handle this?

Additionally, my testing plug is showing the hot and neutrals are reversed on the 110 plugs. Was this a nasty trick, or is there some logical reason for this?

Thanks
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Last edited by Rob Robinson; 12-15-2012 at 07:07 PM.
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  #4  
Old 12-15-2012
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Quote:
Originally Posted by Strayhound View Post
There's 12 volts to the rear heater, but the hot from the heater to the thermostat is only showing between 1 and 2 volts.

It's a Suburban heater.

Meanwhile, the 12 V line to the Dometic 2820 was spliced into the hot from the heater to the thermostat. I'm assuming when the 12 volts suddenly dropped, the power to the Dometic was cut.

I'm now planning to run a single 12V line from the battery directly to the Dometic. Do i need an inline fuse or will the control panel handle this?

Additionally, my testing plug is showing the hot and neutrals are reversed on the 110 plugs. Was this a nasty trick, or is there some logical reason for this?

Thanks
John,
You should be able to find a good 12v source from one of the several 12v panels in the coach, instead of going direct from the battery. If you can't use an empty fused or breakered slot, I would put an inline fuse close to the 12v source that you use.
As far as the 110 being reversed at the outlets, I don't think that is how it came. My FC was not wired that way. Might be something a P.O. did....
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  #5  
Old 12-16-2012
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Quote:
Originally Posted by Strayhound View Post
Additionally, my testing plug is showing the hot and neutrals are reversed on the 110 plugs. Was this a nasty trick, or is there some logical reason for this?

Thanks
Check your shore line connections, that may be where the neutral and hot are reversed. Also re-check using the generator. Unless a Previous Owner messed around, the wiring done by BB should be to code. If both the generator and shore power are reversed check the transfer switch wiring.

Of course, check the wiring on one of the errant outlets to be sure the black and white wires are connected to the proper lug. Most outlets have a gold colored connection for the black(hot) and silver colored for the white(Neutral).
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  #6  
Old 12-16-2012
Strayhound Strayhound is offline
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Default Positive/Neutral reversed on fuse box

I checked the polarity on the shore power and it was correct. I then checked the polarity on the main fuse box in the bus and discovered the neutral bar was energized rather than the hot bar. Which means the A/C power in the bus has not been fused. Any suggestions?
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  #7  
Old 12-16-2012
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Originally Posted by Strayhound View Post
I checked the polarity on the shore power and it was correct. I then checked the polarity on the main fuse box in the bus and discovered the neutral bar was energized rather than the hot bar. Which means the A/C power in the bus has not been fused. Any suggestions?


First -- are you using a 50 amp shore connection or a 30 to 50 amp adapter? Or possibly a 30 to 50 amp special shore line?

If the shore power polarity is correct at the pedistal, then either the shore line is mis-wired, or the shore line connector is mis-wired. Did you check with the generator??? The generator test will show if the transfer switch area could be the problem. If the gennie is good then the shore line circuit is reversed somewhere between the pedistal and the transfer switch.

If you check the main lines coming into the breaker box, is the white connected to neutral and the black and red to the main panel breakers as it should be?
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Last edited by gcyeaw; 12-16-2012 at 03:56 PM.
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  #8  
Old 12-16-2012
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Default Got It fixed...thanks all

Turns out the shoreline plug was reversed. Polarity issue solved. Thanks to everyone for their assistance.
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  #9  
Old 12-16-2012
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Originally Posted by Strayhound View Post
Turns out the shoreline plug was reversed. Polarity issue solved. Thanks to everyone for their assistance.
Good deal. Glad it was easy to fix once found.
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