Diagnose of H2O heater control module...

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nm_shooter

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Joined
Apr 16, 2006
Posts
10
Whoops.  I may have submitted this before I was done typing.  Sorry if this got posted twice.  I have an Atwood GC6A-7E water heater that no longer lights using the control switch over the sink.  We have to manually light it in order to get it to fire up.  No fun.  We can hear the control module sparking... it fires about 7 or 8 times a second, but the spark looks very lame to me... nothing like the spark on an auto.  So my question...

When these start to fail, do they go all at once, or is it possible for them to get a weak spark?  This module is 10 years old, and the spark just does not seem to have much energy content. 

Is it time to replace the module? 

Thanks...

Frank
 

Gary RV_Wizard

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Feb 2, 2005
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At our Silver Springs FL home
Could be replacement time but more likely the igniter just needs adjustment and/or cleaning.  If its sooty, wipe it off.  Then try bending the metal igniter tip ever so slightly toward the nearest side (where the spark jumps to). It should be about 1/8 inch and is surprisingly sensitive to tiny changes of position.

Also clean the 12V power connections to the control board - dirty or corroded conections will casue a drop in voltahe and a weak spark. Sometimes just sliding the connectors off and back on again is enough to solve the problem.
 

John From Detroit

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Apr 12, 2005
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24,798
Location
Davison Michigan
Several years ago my parents had a new house  built, well nearly built, the contractors had gand plans but finishing the job fell to my brother and I (both of who worked in construction at the time)

Anyway, one of the things the contractor did wrong was the furnance.  Seems it often failed to light (Oil fired but the ignition system is very simular to your gas hot water heater)

Finally I took a look at the instalation and instruction manual, and the ignition points.

A great light dawned,  I set the igintion points per the instructions in the service manual (They were WAY out of spec) and it's never (far as I know) missed an ignition since


The above is a true story

The moral is clean the burner tube (as described in your owner's manual, if you need more there is a thread about a refrigerator which would not work on LP There are suggestions there including, if memory serves, a link to attwood's web page)

Then clean the sensors, the spark point, and adjust it per specifications.  Something is most likely out of adjustment
 

nm_shooter

Member
Joined
Apr 16, 2006
Posts
10
John In Detroit said:
The moral is clean the burner tube (as described in your owner's manual, if you need more there is a thread about a refrigerator which would not work on LP There are suggestions there including, if memory serves, a link to attwood's web page)

Then clean the sensors, the spark point, and adjust it per specifications.? Something is most likely out of adjustment

Anybody know what the correct adjustment is for the ignition points on an Atwood GC6A-7E?

I went out tonight and took a look in the dark.  The gap on the igniter is about 0.030", and the only time I saw a spark was on the very last cycle of the sparker when it went into shutdown.  Even then the spark was miniscule.  So I tried an experiment... I went and got an alligator test lead and clipped one lead to the spade lug output and then used insulated pliers to put the other clip very close to the frame.  I turned off the gas and told my daughter to hit the switch.  Only a very, very dim spark when I moved the clip very close to a ground.  I'm suspecting more and more that the issue is the control head, but would be willing to try adjusting the probes before I pull the trigger on a module.

Anybody got specifications on gap size?

Thanks,

Frank

-f-
 

nm_shooter

Member
Joined
Apr 16, 2006
Posts
10
Fixed!

Had a tired module.  Swapped it out with one I bought off of ebay, and fires right up.  This spark is significantly stronger!

Looks like the spark circuit can get wimpy in its old age.  In looking at the board assembly, there are some aluminum electrolytic capacitors near the HV coil.  I betcha that the heat from the water heater puts some nasty wear on them.  Just for grins I'm going to try and replace the electrolytics and see if the spark comes back. 

Thanks to all for input.

Regards,

Frank
 
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