The
DRSNews
March
2004
By
Subscription Only
Published by Dave’s Repair Service, All Rights Reserved
In
this issue:
1)
DRSNews Back Issues are (Finally) Posted!
2) The No-Heat Gas Dryer
3) How to Convert a Gas Dryer to LP
1)
Well, it’s taken longer than I expected, but I finally got the
back issues of
this little newsletter project posted on the
website.
I'm
also working as fast as time allows at posting ‘How to do
it yourself’ articles,
parts specials,
manuals, and anything else
that I think might
be helpful to
you ‘handy’ folks.
Stop
by for a visit and have a look around when you get a chance.
And please send me
your suggestions. But please be
kind (grin) – it’s still a pretty crude site,
but I’m just getting
started!
www.DavesRepair.com
The
DRSNews Back issue index is finally available (to subscribers only),
and the link will be included in every issue. Thanks for waiting for
it!
2)
We’ve talked a lot about Electric dryers that don’t heat, but
have touched
only briefly on the gas side of things, so I
thought maybe
we should take a run at the subject.
As
with electric dryers, the fastest way to diagnose a ‘no heat’
gas dryer is to
start at the heat source and work backwards.
And
the gas version is simpler in one respect – you’re working
with 120 volts,
so there’s only one ‘leg’ of power to be
concerned
with.
You
will want to verify that there’s gas pressure available to
the dryer, but
that’s usually not too difficult.
Heating
system diagnosis on newer models can be more of a challenge,
because many
of them have
front panels without the
full-width bottom access
panels that we
took for granted for
years. Most provide no
easy way to
look at the burner flame, although
a few models
still have a
small observation port in front, with
a removable
cap.
Like
the electric dryer heating element test, I check for
voltage to the
heat source - in this case, the gas valve ass’y,
with the dryer
running. (On models that
require front panel
removal to
watch the burner flame, I usually just run the drum belt
off the pulley.
You can even pull the drum to get it out of your
way.)
Keep
in mind, if you hear the
valve ‘click’ when you start the dryer,
you already know there’s
power to the valve. (You have made
sure the controls aren’t
set to ‘air fluff’, or 'no heat', right? <grin>)
Most
burner valve assemblies connect to power with a 3-wire plug,
and that plug's an easy place to test for 120V. Meter test pins
can usually be inserted
into the back side of this plug pretty easily.
That third wire's just a ground, and if it doesn't happen to
be green, you'll see
that it connects to a metal part in the valve
area. We want to look for voltage on the other two.
If
there’s voltage to the valve but no burner ignition, you’ve
quickly
eliminated a whole bunch of electrical controls as the problem
– timer,
t’stats,
thermal fuse, etc, very quickly. You now
know the problem
lies
in the valve/ignition system itself.
And
proceeding from there isn't too tough.
Basically
the ignition cycle is as follows: At dryer start, you
should hear the
valve click. 5 or 10 seconds later, you should
see the ignitor
start to glow a brilliant red. After it has heated
for a few
seconds, 15 or so, the flame sensor should open and cut power
to it, and
you’ll hear another valve 'click', the valve should
open, and
there’ll be gas flow and a nice blue flame.
Note:
if you're testing this with the front panel and belt off, don't
allow the flame to burn very long. Without the front panel
in place there'll be no airflow through the burner, and the flame
can warm things up more than we want. A few seconds of ignition
is all you need to make sure everything's working
OK, anyway.
Problems,
from most common to the not-so-common:
If
the valve clicks on dryer start the but ignitor doesn’t glow, the
ignitor is
probably open. These are very brittle, and a bad one
is usually
cracked (not always easy to see!) or broken.
In
fact, when
handling a new one, be very careful with it. It's easy
to break these,
and it's even best not to touch them with your
bare fingers.
If
the ignitor glows, then the flame sensor turns it off, but there’s
no flame,
one of the coils is probably open.
These are much easier to
test than the old 'K' valve coils, and can be replaced
individually.
But it’s better to replace them as a set. The best place to buy
those these days is Ebay.
Here are the
current listings for them there.
To
test the coils
with an ohmmeter, here are the resistance readings:
One
of the least common failures is the flame sensor. This little
switch is heated by the
ignitor and flame through a little window.
It
mounts to the side of the burner 'can', usually on the left, and
is just a simple two-wire
switch. When radiant heat warms it enough,
it electrically opens and the burner ignites. The radiant heat
from the flame then keeps it open, the flame heats the ignitor,
which keeps its resistance low, and the gas keeps flowing.
If
the ignitor glows but the gas never turns on, suspect this part.
If
you're comfortable doing so, after the ignitor has glowed a few
seconds, carefully pull off
one of this sensor's wires, and you should get ignition.
That's a quick 'proof' of a bad flame sensor.
These
are surprisingly reliable, though. I recently replaced my first
one in about 3 years of full time service work!
3)
Conversion to LP is pretty easy with this valve too, and is a really
common job here in the
country. It's getting a little more involved
lately with some brands,
because they're playing games with
burner venturi's
and make you replace the burner tube.
The
conversion kits are more expensive, but the job's still not a big
deal.
Basically,
if you don't have to change the tube, it's only a matter of
changing the burner orifice
and replacing the brass regulator vent
with a block-open pin.
Orifices, pin, instructions, and labels to
let everyone
know it's been converted, are all supplied in the kits.
Here's
a picture of the typical component layout on the 'M' valve burner
assembly:
And
let me know if you have any trouble locating a conversion kit
for your dryer. I carry many of them in stock, and most of those
I don't stock can be here 'next-day'.
***
Thanks
again for allowing me into your inbox
again this month. I really enjoy this project, and hope you benefit
from it.
Feel
free to invite others to subscribe that you think might enjoy
it.
Also,
if you have any topics you’d like to see
discussed here or
covered in an online article, let me know and I’ll do my best
to oblige. The website is a resource I'm excited about, because
it allows a lot more flexibility and depth than email.
Thanks
for all your encouragement - I really appreciate it! May
the Lord richly
bless you & yours!
Sincerely,
Dave
Harnish
Dave’s Repair Service
New Albany, PA
drs@sosbbs.com
www.DavesRepair.com
‘For
thus saith the high and lofty One that inhabiteth eternity, whose
name is Holy; I dwell in the high and holy place, with him also
that is of a contrite and humble spirit...’
Isaiah 57:15
Appliance
Help (and a lot of other stuff!) for the Handy:
www.DavesRepair.com