No power to water heater?

[Ms. Kristy]

I have an Atwood water heater in my coach. Thought the problem was with the board, replaced that but to no avail I can not figure out why it is not getting power to the DSI? I'm really frustrated, I checked all of the fuses the other switches on the panel inside the motorhome are getting power. So why won't this thing spark for me? Before this happened a light would come on when the switch was push for the pilot. Now NOTHING happens when I flip that switch. The old board was Bad. Had it tested. But still no hot water. Can someone please help me?

 

[John From Detroit]

Step one: IS THE BOARD getting power. if its not, that's your problem.

Second, the DSI may be getting power but if the points are too far apart (CONSULT THE MANUAL FIRST) it may not be able to jump the gap.

And that is just two of the possible causes.

 

[Ms. Kristy]

How can I test to see if the board is getting power?

 

[Gary RV_Wizard]

You can get an Atwood heater service manual here:
http://bryantrv.com/docs2/docs/atwoodwaterheater.pdf

There is a +12v lead to the controller board, and from there the power passes through the thermostat and ECO to the gas valve. There is also usually a temperature sensitive fusible link in that wire that detects heat/flame outside the burner. If that melts, no power passes through. The specific wiring path depends on the model of the heater - there are three basic Atwood wiring layouts.

 

[Ms. Kristy]

Thank you!

 

[Ms. Kristy]

Could the problem originate from the lead coming off of the house battery?

 

[Gary RV_Wizard]

Not if you have 12v power elsewhere. There should be a wire for the water heater, but it will have a fuse that might be blown.

Is it possible you reversed the plus (hot) and minus (ground) wires to the heater board? The electronics are sensitive to that.

 

[John From Detroit]

Also when you test for power to the board.... Use a test light, not a volt-meter, I have had the meter tell me "Good voltage" but the light did not light.. Problem was a very high resistance spot in the wire,, The meter draws next to no current so the resistance did not bother it but the 1 amp the test lamp drew.. Took it down fast.

 

[teddyu]

Just had to replace the T-stat (and ECO).  Neither the 120V or the gas would fire.  Check by removing the two brown wires from the T-stat.  Check the T-stat for continuity.  If no continuity, T-stat has failed.  Need to replace.  About $12 on Amazon.  JM2?...