Vince Pitelka on sun 7 dec 03
Rick Hamelin wrote:
"Lately, I have been researching the direct vent and non-venting gas
heaters for use in my studio. These affordable stoves have a sensor that
detects if the flame is absent at the pilot and shuts down the valve. I
cannot conclude their adaptability to our use but I believe that they are
more affordable priced compared to the industrial versions. This I believe
is the fire eye that you refer to, but I really don't know. Many new kitchen
stoves have the same feature. The question is would these home appliance
rated systems work on some kiln burner systems? They could be more
reasonably price or scavanged from a old stove. Ideally, it would be great
if it could also be connected to an alarm to alert us when the pilot dies.
Rick -
I'd like to know more about those as well. The ones I am familiar with have
simple Baso valves. I have one of those un-vented units in my house as a
backup in the event of power failures, since it does not use any AC power.
As far as I know, those systems are not anything like a fire-eye, because
the fire-eye system requires electric power and a small computer to
interpret what the infrared or ultraviolet senser sees. It is true that all
such electronic modules are becoming much more reasonably priced, but the
fire-eye system is still pretty elaborate, and generally very expensive.
I'd love to see someone come up with a more affordable, accessible version
of the fire-eye. It has the advantage of being instantaneous, whereas with
a Baso system, the thermocouple must cool off quite a bit before the Baso
valve shuts off the gas supply. With the Baso system, the thermocouple
generates its own miniscule electric current which is enough to energize the
small electromagnetic latching device in the Baso valve body.
With a proper fire-eye system, as soon as the flame goes out, the system
kicks in. The less expensive fire-eye systems just shut off the gas like a
Baso valve, bu tthey do it instantaneously. Those ones must be manually
reset and relit every time, just like a Baso valve. But even those fire-eye
systems require an infrared or ultraviolet "fire-eye" sensor, a resettable
controller, and an electromagnetic gas valve, and the controller and
electromagnetic valve run on AC power.
The more expensive fire-eye systems such as are used on Geil Kilns and most
glass furnaces are true reignition system, often referred to as "flame
rectification" systems. With those systems, when the fire eye senses that
the burner or pilot flame (depending on individual setup) is out, the
computer activates a spark coil which produces a high-voltage spark at the
burner tip. If the flame reignites, everything proceeds as normal. If the
flame does not reignite, the system usually cycles several times to allow
fresh air to flush the burner and flues, and if the flame still does not
reignite, the whole system shuts down and must be manually reset.
So, as you can see, even the simpler fire-eye systems are pretty complicated
and expensive in comparison to a Baso valve system.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
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