defroster tube coil shorted out

another problem. checked with a meter and found the glass tube defrost element shorted open.
the element can be viewed by pulling off the rubber caps at each end of the glass tube.
i looked at the elment inside and the element 'spring' was pretty much fused together on one of its outer sides (the side was in contact with the glass?) and finally at one extreme the element broke throgh high current.
why do glass tube element defrosters fail? i had verified it was the same power rating as the previous one. Is it because water gets inside tube? or condensation?
thanks, K
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This is Turtle.
Well if you put your fingers on the glass tube when your installing the new heater. It will burn out in short order depending on how much oil or grease you have on your fingers. You can go wash your hand real good but with in about 2 minutes the oil will be put back on your fingers. so when installing the element you should not touch the glass at all and do clean the glass element with a clean cotton cloth before installing it.
So if you touch it with your bare fingers while installing it , expect to change it out in the very near future !
TURTLE
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Good point, my shelled one!
Good idea to were rubber gloves. Same thing goes with car/truck headlamps......
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Do or do not, Luke, there is no "shorted open" ;)
The electricity takes an un-wanted "short cut" or it's stopped by an "open" in the circuit. Pick one. ;)
I know what you're doing, no big deal, but "short" is used as a catch-all for "electrical problems" by those that don't know better.
Sometimes there's a need to "short circuit" something on purpose. That's not called a short either tho, then it's called a shunt. :)
Shorts are sometimes a pain in the neck to find, opens can be found with a meter.
I'm really glad you got a meter and using it, BTW! :)
Alvin in AZ (retired RR signal maintainer)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I think you're full of shunt!
EAT my shorts!!!
;-]
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
komodore comrade wrote:

Hi,
Moisture getting inside, defrost thermostat allowing the heater to get too hot, *hit happens, someone touched the glass part and left an oily print which causes an hot spot.
These are the most common causes.
jeff. Appliance Repair Aid http://www.applianceaid.com /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
another problem. checked with a meter and found the glass tube defrost element shorted open. CY: Polar oposite problems. Shorted is an unwanted electrical path, and open means no electric flow.
the element can be viewed by pulling off the rubber caps at each end of the glass tube. CY: Which action (pulling the ends off) you must never do.
i looked at the elment inside CY: Did you wear factor 17 dark sunglasses or a welding helmet while viewing the spring?
and the element 'spring' was pretty much fused together on one of its outer sides (the side was in contact with the glass?) and finally at one extreme the element broke throgh high current. CY: How do you know it broke through high current?
why do glass tube element defrosters fail? CY: Oxidation, sounds like.
i had verified it was the same power rating as the previous one. CY: How'd you verify this?
Is it because water gets inside tube? or condensation? CY: Can be.
thanks, K
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
thanks for all the feedback.i will answer some questions that many people asked:

its something like this (quartz glass tube heater element) looks like http://www.chhaperia.com/products_defrost.htm the coils are also available sperately from the net. (like
http://www.duralite.com/images/Variwatt%204.jpg )
the ends are like those of a sparkplug ignition leads, so i didnt think there was any gas/vacuum inside.they are push fit and have a sort of hook for element wire

the dissecting took place with fridge off.i didnt know they generated that much light.if mine was that powerful i reckoned over the years i should be able to see it light up through the seams and vent holes when the freezer defroster turned on.

at the point of breakage there was a tiny bead on each end of the coil

the old one had marked on it 200W. P=IV so 200=I * 110 = 1.8A V=IR R=V/I 110/1.8` ohms. checked that the replacement was also approx 60 ohms
with shorted open i meant that current , instead of travelling through all the loops of wire in the coil, travelled along the outside of the coil in a straight line (the short). the now shorted coil has less resistence than before so more current passed through which melted the extreme end of the coil (the 'open') . sorry for any confusion
i am still puzzled about the short. the coil (painted on/treated) insulation apparently broke down along the length of one side. i assume it was a side in contact with the glass...........hmmmm should heating elements be in contact with the sides/bottom of the glass or should they be tensioned so as to be suspended? this would be quite difficult to do with a fridge coil as its diameter almost matches that of the glass tube exactly.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
thanks for all the feedback.i will answer some questions that many people asked:

its something like this (quartz glass tube heater element) looks like http://www.chhaperia.com/products_defrost.htm the coils are also available sperately from the net. (like
http://www.duralite.com/images/Variwatt%204.jpg )
the ends are like those of a sparkplug ignition leads, so i didnt think there was any gas/vacuum inside. CY: They are not designed to be dissembled, so it's not wise to pull the ends off. Vacuum is not the point.
they are push fit and have a sort of hook for element wire CY: Still not designed to be dissembled.

the dissecting took place with fridge off.i didnt know they generated that much light.if mine was that powerful i reckoned over the years i should be able to see it light up through the seams and vent holes when the freezer defroster turned on. CY: You still have eyesight in both eyes? Well, I guess it was burnt out by this time.

at the point of breakage there was a tiny bead on each end of the coil CY: Boy, that sounds just like overheating.

the old one had marked on it 200W. P=IV so 200=I * 110 = 1.8A V=IR R=V/I 110/1.8` ohms. checked that the replacement was also approx 60 ohms CY: That's pretty technical.
with shorted open i meant that current , instead of travelling through all the loops of wire in the coil, travelled along the outside of the coil in a straight line (the short). the now shorted coil has less resistence than before so more current passed through which melted the extreme end of the coil (the 'open') . sorry for any confusion CY: Still confusing.
i am still puzzled about the short. the coil (painted on/treated) insulation apparently broke down along the length of one side. i assume it was a side in contact with the glass...........hmmmm should heating elements be in contact with the sides/bottom of the glass or should they be tensioned so as to be suspended? CY: The goal is to make heat, and get the heat to the frost. This works better when the coil is in contact with the tube.
this would be quite difficult to do with a fridge coil as its diameter almost matches that of the glass tube exactly. CY: And, so it should match.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
the replacement tube i got, although according to my mathematics was of similar resistance to its predecessor, was a 12inch model instead of 23inch of the original one.
could this be a reason why the replacement overheated and broke? or is it due to more current passing through the circuit than the 400w sticker on the original would suggest.
could a faulty defrost thermostat or defrost timer have cause the overheating? thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
More likely a weak area in the metal filament. Not much you can do about it.
--

Christopher A. Young
Learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.