Atwood 8531-III No heat
Steve in AZ
Atwood 8531-III. Worked one night, not the next. Swapped out board with
another unit, same symptom:
Blower comes on, no ignition. I can hear the sail switch engage, but that's
it. I'll troubleshoot more tomorrow, but curious if there's a "common"
problem with these.
TIA,
Steve
No trees were killed in the sending of this message. However a large number
of electrons were terribly inconvenienced.
richard
thermocoupler?
I had one go out on a house furnace once. Replaced it and the furnace
ignited just fine.
Lone Haranguer
> Greetings my RORT friends....
>
> Atwood 8531-III. Worked one night, not the next. Swapped out board with
> another unit, same symptom:
>
> Blower comes on, no ignition. I can hear the sail switch engage, but that's
> it. I'll troubleshoot more tomorrow, but curious if there's a "common" problem
> with these.
>
disconnected the gas line and checked to see if gas is getting to the unit?
LZ
Lone Haranguer
From an Atwood forum.
> Atwood 8531-III
Re: Repair manual Model 8531 Atwood RV furnace
you can download diagnostics from the Atwood web site. The below is an example.
http://www.myrvguide.com/current_category.2177/Forum.124577/forum_thread_full.html
A short way down it gives conditions and solutions.
LZ
Technobarbarian
"richard" <mem...@newsguy.com> wrote in message
news:1qkxsik24hx5t$.1nlfwr6d2mjw6.dlg@40tude.net...
There's only one tiny technical problem with this answer. An
electronic ignition furnace has neither a "thermocoupler" or a thermocouple.
Since you've eliminated just about everything else the most common
problem is gunk or insect nests built up on the igniter. It's also possible
that it isn't making a spark because the spacing between the igniter and its
ground is wrong. After that I'd look for a short in the igniter wiring and
make sure the fan switch is actually closing when it "engages".
Here's the manual for the 8531-IV. There probably isn't much
difference between that one and yours.
http://www.atwoodmobile.com/manuals/furnaces/MPD%2033179%20SP%201.08.pdf
TB
richard
Did I not say house furnace?
And it was one possibility, not the only one.
Lone Haranguer
What is the function of a thermocouple, richard?
LZ
richard
No I am not getting into an argument with you over this.
It is your privilege to agree or not agree.
I made my statement based upon my similar experience. Now you want to turn
this into a technical shooting match?
Not this time.
nothermark
So how does the flame sensor work?
Technobarbarian
"nothermark" <nothe...@not.here> wrote in message
news:u38397prl39k44i17...@4ax.com...
The heat of the flame ionizes the gas. This allows a small current from
the circuit board to pass through it. If the flame sensor has a lot of soot
or dirt built up on it the current won't pass through the sensor which will
shut off the furnace after a set interval.
Since the OP can hear the sail switch engage he should also be able
to hear the igniter sparking. Because he doesn't report that I'm assuming he
isn't getting a spark to start with. Either way the usual solution is to
buff the sensor with emery cloth or fine sandpaper.
TB
nothermark
Thanks. Sounds like what I have at the house. I was not sure from
the diagram. It looks like they use the same electrode for the spark
and the sensor. If so I would love to see the schematic. Those
circuits get interesting. ;-)
Technobarbarian
"Technobarbarian" <Technobarbar...@gmail.com> wrote in message
news:j6sheg$fo0$1...@dont-email.me...
everything shuts off except the blower.
TB
Technobarbarian
"nothermark" <nothe...@not.here> wrote in message
news:mhj3971tb4a1emsnk...@4ax.com...
> Thanks. Sounds like what I have at the house. I was not sure from
> the diagram. It looks like they use the same electrode for the spark
> and the sensor. If so I would love to see the schematic. Those
> circuits get interesting. ;-)
Other than size there really isn't much difference between RV and
residential furnaces. The main difference is that a residential furnace will
draw air for combustion from the surrounding air, while a RV furnace has to
draw its combustion air from outside the RV. You are correct, the igniter
and the sensor are usually the same electrode.
TB
Steve in AZ
ignition...
Steve
"Steve in AZ" wrote in message news:ln6kq.1880$rR6....@newsfe04.iad...
Steve in AZ
volts it needed to operate. two white wires run back into the combustion
chamber. I popped to top, jiggled them and it now works. Is there a
secondary sail or safety switch in there?
Steve
"Steve in AZ" wrote in message news:ln6kq.1880$rR6....@newsfe04.iad...
Greetings my RORT friends....
PDDeen
> I played around today and found that the control board wasn't getting the 12
> volts it needed to operate. two white wires run back into the combustion
> chamber. I popped to top, jiggled them and it now works. Is there a
> secondary sail or safety switch in there?
>
> Steve
>
down if it gets too hot. It may have problem there. On mine the burner
turns on and off several times before the fan shuts down. Dealer said
that is normal but in all the rvs I've owned, none of them did that.
It takes @30 minutes to raise temp 3 degrees in trailer. Anyway, check
the wiring diagram and the overtemp sensor should be there.
PDDeen
Technobarbarian
"Steve in AZ" <fixm...@gmail.com> wrote in message
news:bmukq.2441$ma7....@newsfe19.iad...
> 12
> volts it needed to operate. two white wires run back into the combustion
> chamber. I popped to top, jiggled them and it now works. Is there a
> secondary sail or safety switch in there?
are the flame sensor and an over-heat switch inline with the sail switch.
The wiring diagram for the 8531-IV in the manual on the Atwood website is
probably pretty much the same as yours. The main difference is probably
different parts numbers on some of the components.
TB