Fixing a ceramic heater for a family member. Started blowing cold air.
It's very similar to this one:

https://en.wikipedia.org/wiki/File:G...mic_heater.jpg

It has a NC safety temperature switch fitted, this has failed open. One of
the spade lugs has clearly overheated. The switch is shown at the bottom
of this pic:

http://www.zuglet.com/ev/saturn/imag...micElement.jpg

It's marked KSD301 250V 10A. But there is no temperature marking

There is also a thermal fuse, this is OK.

This ebay auction:

http://www.ebay.co.uk/itm/262117559259

shows replacements with temperature values ranging from 40C to 160C. Can
anyone suggest what value I should choose?

The heater works OK with the wires to the switch shorted, but I would like
to replace it.

Thanks.

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

On 26/02/2016 15:07, Mike Tomlinson wrote:

Fixing a ceramic heater for a family member. Started blowing cold air.
It's very similar to this one:

https://en.wikipedia.org/wiki/File:G...mic_heater.jpg

It has a NC safety temperature switch fitted, this has failed open. One of
the spade lugs has clearly overheated. The switch is shown at the bottom
of this pic:

http://www.zuglet.com/ev/saturn/imag...micElement.jpg

It's marked KSD301 250V 10A. But there is no temperature marking

There is also a thermal fuse, this is OK.

This ebay auction:

http://www.ebay.co.uk/itm/262117559259

shows replacements with temperature values ranging from 40C to 160C. Can
anyone suggest what value I should choose?

The heater works OK with the wires to the switch shorted, but I would like
to replace it.

Thanks.


I've never known the bimetal dome to fail on these, always the contacts
or the little ceramic trigger out of position.
First with a soldering iron barrel , confirm by listening for a click
over, then repeat with a thermometer, glass or pyro.

En el artículo , N_Cook
escribió:

I've never known the bimetal dome to fail on these, always the contacts
or the little ceramic trigger out of position.
First with a soldering iron barrel , confirm by listening for a click
over, then repeat with a thermometer, glass or pyro.

It's open circuit, with a burnt spade terminal. Trust me, it's u/s.

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

On 26/02/2016 16:16, Mike Tomlinson wrote:
En el artículo , N_Cook
escribió:

I've never known the bimetal dome to fail on these, always the contacts
or the little ceramic trigger out of position.
First with a soldering iron barrel , confirm by listening for a click
over, then repeat with a thermometer, glass or pyro.

It's open circuit, with a burnt spade terminal. Trust me, it's u/s.


But not the dome, hack into it and extract the dome.
Now not constrained, you need to make sure it does not fly off , when
it flips to the opposite state.

In sci.electronics.repair Mike Tomlinson wrote:
https://en.wikipedia.org/wiki/File:G...mic_heater.jpg

I have a similar heater that I bought here in the US, branded Holmes,
made in China. It is rated at 1500 W, 120 V, 60 Hz. As a first cut,
their product support page

http://www.holmesproducts.com/servic...neral-faq.html

says the "overheat shutoff temperature" varies from 149 to 265 F, or
about 65 to 130 C. Note that this covers both ceramic and non-ceramic
heaters.

Taking mine apart, the ceramic core is about 3.25 x 3.5 x 0.5 inches,
or about 83 x 89 x 13 mm. If yours is very different than this, then it
may need a different temperature rating!

The safety switch is an "open frame" design, like the one seen in the
picture you linked -

http://www.zuglet.com/ev/saturn/imag...micElement.jpg

- and not an enclosed one like the KSD301 Ebay link you gave. When
installed, the bimetal with contacts is about 0.125" or 3 mm away
from the top edge of the ceramic core.

It is marked AUONE, AUT95P, and has VDE and USA-Canada UL component
marking ("backwards RU").

Google leads me to http://www.auone.com/showproduct13.asp?ProID=1849 .
The part I have looks like their "AUT-P" series (with the white plastic
tab), which lets me *guess* that the "95" in the part number means
95 C (or 203 F). Again, this is _just a guess_.

Please proceed with caution. The house you don't burn down may be
your own.

Matt Roberds

En el artículo , escribió:

says the "overheat shutoff temperature" varies from 149 to 265 F, or
about 65 to 130 C. Note that this covers both ceramic and non-ceramic
heaters.

A useful data point, thanks.

Taking mine apart,

You didn't have to go to that much trouble, but thank you.

the ceramic core is about 3.25 x 3.5 x 0.5 inches,
or about 83 x 89 x 13 mm. If yours is very different than this, then it
may need a different temperature rating!

3.5" x 3.25", so very similar. There's 4 ceramic cores with two heat
levels selected by a switch (heat level 1 = 2 cores operating, heat
level 2 = 4 cores operating)

Ceramic elements are PTC so self-regulating to an extent.

Google leads me to http://www.auone.com/showproduct13.asp?ProID=1849 .
The part I have looks like their "AUT-P" series (with the white plastic
tab)

That sounds like a resettable one.

, which lets me *guess* that the "95" in the part number means
95 C (or 203 F). Again, this is _just a guess_.

It's also right in the middle of the "65 to 130C" shutoff temperature
you quote above.

Many thanks.

Please proceed with caution. The house you don't burn down may be
your own.

Obviously, I need to choose a sensible temperature for the cutoff - too
low, and it'll trip on and off all the time. There is also a thermal
fuse as a belt-and-braces measure at the top of the ceramic frame. I
haven't looked to see what temperature rating it is. Obviously, if that
fails, it will fail open permanently.

The ceramic element is held in place in a hard plastic frame, so isn't
going to be allowed to get very hot.

I'll try a 95C switch with a temporary neon indicator on the feed to the
element to see if it's cycling excessively, and go from there.

It's a nice little heater, very quiet and efficient, so worth a bit of
time.

Thanks again.

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

Mike Tomlinson wrote:
En el artículo , escribió:

Taking mine apart,

You didn't have to go to that much trouble, but thank you.

I use it a lot in fan-only mode, so it was about ready for its annual
dusting anyway.

There's 4 ceramic cores with two heat levels selected by a switch
(heat level 1 = 2 cores operating, heat level 2 = 4 cores operating)

Same here.

The part I have looks like their "AUT-P" series (with the white
plastic tab)

That sounds like a resettable one.

It is. There is no user-resettable button; you just have to unplug
the heater and let it cool off.

The ceramic element is held in place in a hard plastic frame, so isn't
going to be allowed to get very hot.

Same here. On mine, the frame also extends back towards the intake to
hold the fan motor and make a venturi/shroud for the fan blade.

Matt Roberds

En el artículo , escribió:

On mine, the frame also extends back towards the intake to
hold the fan motor and make a venturi/shroud for the fan blade.

Yes, same here. It's all one piece. The section holding the ceramic
element is square, then there's a short cylinder to the fan housing
which is square. The lot fixes to the back half of the enclosure with 4
screws.

I suspect this is pretty much a commodity part made in China and badged
with OEM logos as required.

I've ordered the 95C switch, pretty sure that'll do the trick. Thanks
again for your help, have a virtual pint on me

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

On Sat, 27 Feb 2016 03:08:39 +0000, Mike Tomlinson
wrote:

En el artículo , escribió:

says the "overheat shutoff temperature" varies from 149 to 265 F, or
about 65 to 130 C. Note that this covers both ceramic and non-ceramic
heaters.

A useful data point, thanks.

Taking mine apart,

You didn't have to go to that much trouble, but thank you.

the ceramic core is about 3.25 x 3.5 x 0.5 inches,
or about 83 x 89 x 13 mm. If yours is very different than this, then it
may need a different temperature rating!

3.5" x 3.25", so very similar. There's 4 ceramic cores with two heat
levels selected by a switch (heat level 1 = 2 cores operating, heat
level 2 = 4 cores operating)

Ceramic elements are PTC so self-regulating to an extent.

Google leads me to http://www.auone.com/showproduct13.asp?ProID=1849 .
The part I have looks like their "AUT-P" series (with the white plastic
tab)

That sounds like a resettable one.

, which lets me *guess* that the "95" in the part number means
95 C (or 203 F). Again, this is _just a guess_.

It's also right in the middle of the "65 to 130C" shutoff temperature
you quote above.

Many thanks.

Please proceed with caution. The house you don't burn down may be
your own.

Obviously, I need to choose a sensible temperature for the cutoff - too
low, and it'll trip on and off all the time. There is also a thermal
fuse as a belt-and-braces measure at the top of the ceramic frame. I
haven't looked to see what temperature rating it is. Obviously, if that
fails, it will fail open permanently.

The ceramic element is held in place in a hard plastic frame, so isn't
going to be allowed to get very hot.

I'll try a 95C switch with a temporary neon indicator on the feed to the
element to see if it's cycling excessively, and go from there.

It's a nice little heater, very quiet and efficient, so worth a bit of
time.

Thanks again.
Nice as it is the efficiency is same as any other electric heater. All
the power going into it becames heat in the room it's in.
ERS