Gas Hot water heater intermintant.. i can make it work... sorta..

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st - 15 Oct 2007 05:39 GMT

i have a 1984 fleetwood southwind.. atwood htr board pn#
mpd91731...if i send 12 v pos to either side of ECO red wire it will
fire up (spark and burn gas) as ling as i send 12 v.. if i disconect
either brown tstat wire and reconnect; it waits 3 sec .. it fires up
for 6 sec and quits... it my tstat bad? is it the board? what is the
ECO? thanks.. this forum rocks!!!

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st - 15 Oct 2007 18:20 GMT

> i have a 1984 fleetwood southwind.. atwood htr board pn#
> mpd91731...if i send 12 v pos to either side of ECO red wire it will
> fire up (spark and burn gas) as ling as i send 12 v.. if i disconect
> either brown tstat wire and reconnect; it waits 3 sec .. it fires up
> for 6 sec and quits... it my tstat bad? is it the board? what is the
> ECO? thanks.. this forum rocks!!!

I figured it out.. ECO is emer cut off.... There was a loose black
wire coming out of the middle of the board that needed to be connected
to a temp sensor that shows resistance to ground when the flame hits
it.. other wise the gas gets cut off....i wish todays electronics were
"this" logical... perhaps they are, but I cant see inside of an IC
chip... but i sure can test 12v and resistance... :)

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Zyp - 16 Oct 2007 01:18 GMT

>> i have a 1984 fleetwood southwind.. atwood htr board pn#
>> mpd91731...if i send 12 v pos to either side of ECO red wire it will
[quoted text clipped - 9 lines]
> "this" logical... perhaps they are, but I cant see inside of an IC
> chip... but i sure can test 12v and resistance... :)

It's likely "flame rectification." The presence of a flame in contact with
a probe allows a dc voltage to flow through to ground. The electronics pick
up on the dc voltage and allow the main gas to stay on [gas valve.] Be sure
the proble is clean and there is a good ground connection for the burner.

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Zyp

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st - 19 Oct 2007 05:05 GMT

> >> i have a 1984 fleetwood southwind.. atwood htr board pn#
> >> mpd91731...if i send 12 v pos to either side of ECO red wire it will
[quoted text clipped - 17 lines]
> --
> Zyp

thanks for all the help!!

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