SCR dimmer control for portable electric heater??

[mike]

me@privacy.net wrote:

mike <spamme0@go.com> wrote:

How much improvement are you expecting?

The goal was to keep internal thermostat contacts from
wearing out.....IF and only if I could get a heavy duty
enough unit at low cost that is

Interesting that there's no mention of that goal in your original statement.

Plus it seems to me it would help give more even heat?

Based on what?
Point your thermometer at the heating surface.
What's the temperature when it first turns on?
What's the temperature when it cycles off?
That delta-t is the measurement of heat evenness.
This can be a big number with a radiant heater.
Can be almost zero with a well-designed
radiator style heater. The whole idea of the radiator
is to have some thermal mass and keep heat even.

 

[KR]

On Mar 22, 2:56 am, m...@privacy.net wrote:

mike <spam...@go.com> wrote:
How much improvement are  you expecting?

The goal was to keep internal thermostat contacts from
wearing out.....IF and only if I could get a heavy duty
enough unit at low cost that is

Plus it seems to me it would help give more even heat?

They wont wear out in a hurry.
I would also be wary of removing the existing thermostat from the
circuit, as in most cases, it not only regulates the temperature to
the point you set, but also has a second function of "over
temperature" emergency cutoff, that will kill power if the temperature
exceeds a certain limit. (usually can only be reset by pressing a
button once this trips).

While you may think this isn't needed, if it is bypassed and the unit
were to overheat, it could start a fire or even rupture from the
pressure of the overheated internal oil (if an oil filled heater) ,
spraying very hot oil everywhere.

A light dimmer type setup, if it fails, will typically result in the
internal TRIAC short circuiting, which will leave the heater on full
power, constantly, resulting in a risk of overheating. AS a light
dimmer also has no "thermostat" to measure the heat coming from the
unit, you would have to constantly adjust it as the temperature
changes, whereas a thermostat will try to maintain a temperature at a
certain level, regardless of the existing room temperature. (ie: if
the room is a couple of degrees colder than last night, a thermostat
will simply leave the power on for longer time if needed until the
desired temp is reached, then shutoff. A light dimmer will still only
leave the power on at a % of full, and will not give it any extra to
compensate for this. This means you will have to keep adjusting it on
a "trial and error" basis to set the right temp as room temperatures
change with weather.

 

On Sun, 21 Mar 2010 17:23:11 -0400, mm
<NOPSAMmm2005@bigfoot.com>wrote:

On Sun, 21 Mar 2010 11:56:40 -0500, me@privacy.net wrote:

mike <spamme0@go.com> wrote:

How much improvement are you expecting?

The goal was to keep internal thermostat contacts from
wearing out.....IF and only if I could get a heavy duty
enough unit at low cost that is

I've only had one thing where the contacts wore out and that was
decades old. Not counting engine ignition points.

Plus it seems to me it would help give more even heat?


Why would it do that.

If you want more heat, turn the thermostat up.

AIUI, this should have been cross-posted to alt.home.repair, instead
of asking the same question in two newsgroups. That way everybody
could have the benefit of what others say, and they wouldn't repeat
what was said elsehere already.

No it should not have been cross posted to a group full of fucking
idiots like you.

 

mike <spamme0@go.com> wrote:

The whole idea of the radiator
is to have some thermal mass and keep heat even.

there is no thermal mass in this heater.....it is
mica-thermic

 

[GregS]

In article <rk3dq5h1oj5ma64jh080ndgrlemk4rao7e@4ax.com>, mm <NOPSAMmm2005@bigfoot.com> wrote:

On Sun, 21 Mar 2010 14:23:49 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


William Sommerwerck wrote:

I rather like the idea of wiring two heaters in series. This
will reduce the total output to half of what it was, but it will
be better spread around the room, which might be a net
improvement.

Why not use 4 heaters in series? Or maybe even 8 or 12 or 16?

How about warming the whole floor.

How about four in series-parallel? That would be the same heat output as
one, but you'd (probably) need to cycle them on less often for the same
degree of comfort.

Regardless, I've never understood why radiators and heating fixtures are
place right next to the windows.

Much less of a problem with efficient windows.

If they are placed along inner walls the room temperature is uneven.
Since heat escapes through walls, windows & doors you need to replace
it. Then, the center of the house will stay warm from convection
currents and the lower heat loss through a ceiling or roof.

The upward current warms that ordinary cool downward draft. Drafts affect
overall rooms comfortability. I installed, or rather insulated my front door,
and the room is much better.

He makes a good point however. By placing them near the window, the
hottest part of the room is near the window and the most heat loss
occurs, compared to placing it somewhere else.

Maybe having the room temperature even is something some people would
sacrifice to save money, and that pesky old environment and balance of
payments. And that way the people who like it warm could sit on one
side of the room and the ones who are hot all the time could sit on
the other.

 

[mike]

me@privacy.net wrote:

mike <spamme0@go.com> wrote:

The whole idea of the radiator
is to have some thermal mass and keep heat even.


there is no thermal mass in this heater.....it is
mica-thermic

You probably shoulda been more accurate with your initial
"radiator" description.
Garbage in >>> garbage out...

 

[Robert Macy]

On Mar 20, 8:17 pm, isw <i...@witzend.com> wrote:

In article <ho40m3$t3...@news.eternal-september.org>,
 "William Sommerwerck" <grizzledgee...@comcast.net> wrote:

Does anyone know of an SCR control hefty enough
to handle this kind of resistive heating load??

Or (maybe) better yet, how about some kind of PWM
control?

SCR dimmers use PWM.

I rather like the idea of wiring two heaters in series. This will reduce the
total output to half of what it was, but it will be better spread around the
room, which might be a net improvement.

It will reduce the current to (approximately) half, which will reduce
the heat output (power) to one-quarter that of a single unit. Power is
I^2*R.

Isaac

well said, now include the thermal coefficient for the filament...

 

[GregS]

In article <isw-99FC9A.20175320032010@[216.168.3.50]>, isw <isw@witzend.com> wrote:

In article <ho40m3$t33$1@news.eternal-september.org>,
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote:

Does anyone know of an SCR control hefty enough
to handle this kind of resistive heating load??

Or (maybe) better yet, how about some kind of PWM
control?

SCR dimmers use PWM.

I rather like the idea of wiring two heaters in series. This will reduce the
total output to half of what it was, but it will be better spread around the
room, which might be a net improvement.

It will reduce the current to (approximately) half, which will reduce
the heat output (power) to one-quarter that of a single unit. Power is
I^2*R.

You forgot to multiply twice the resistance. It will be 1/2 the watts total.
Each unit will be 1/4.


greg

 

[Robert Macy]

On Mar 20, 5:07 pm, m...@privacy.net wrote:

I have one of those 1500 watt radiator style portable
electric heaters. Love it

However, rather than the built in thermostat turning
the unit OFF?ON every 15 min's or so,  I was thinking
it would be more efficient to use an SCR dimmer control
to vary the amt or power it gets?

Does anyone know of an SCR control hefty enough to
handle this kind of resistive heating load??

2nd attempt to post this reply!

use a saturable core reactor, which is a variable inductor controlled
by a DC current through a secondary winding. Used to be made by
Northlake near Chicago.

The inductor, with 0 DC current has maximum inductance and 'starves'
the resistive load down to 5 to 10%, then at maximum DC current the
inductor is saturated and almost all the power makes it to the load.
The transfer/control is monotonic, but very weird. L vs Idc

The DC control winding is wound in a 'fgirue eight' pattern so that
one adds, one subtracts with no net to the other winding, but due to
the high number of turns, saturates the core locally. Saturating
locally interrupts the magnetic field lines and is like opening up a
large air gap in the core, thus the inductance drops to nil.

I prefer radiant heaters, too. You can point them at yourself and sit
very comfortably like in front of a fireplace. Used to have hot air
blast heating but that made the room's air excessively hot in order to
be comfortable when sitting. Then when you get up and move around you
swelter. Whereas with radiant heat, the air can stay cool so when you
move around, you're still comfortable. But those contact closures!!!
very irritating if you went to sleep, they get very loud.

The variable inductor is great for controlling resistive loads
especially in the 1kW to 10kW ranges. ...you can actually make your
own if you want.

 

Robert Macy <macy@california.com> wrote:

The variable inductor is great for controlling resistive loads
especially in the 1kW to 10kW ranges. ...you can actually make your
own if you want.

Is this called a "Variac"?

 

[Jeffrey D Angus]

me@privacy.net wrote:

Robert Macy <macy@california.com> wrote:

The variable inductor is great for controlling resistive loads
especially in the 1kW to 10kW ranges. ...you can actually make your
own if you want.


Is this called a "Variac"?

Not really, a variac is just a variable auto-transformer. giving
you a 0-100% range of output vs input voltage, and has a defined
curent limit based on physical size.

The variable inductor, is more of a magnetic amplifier type of
device and relies on the core of the inductor saturating to vary
the series imedpance with the load.

Jeff



--
“Egotism is the anesthetic that dulls the pain of stupidity.”
Frank Leahy, Head coach, Notre Dame 1941-1954

http://www.stay-connect.com

 

[Phil Allison]

"Robert Macy"

well said, now include the thermal coefficient for the filament...


** It a HEATER - you fucking IMBECILE.



.... Phil

 

[Robert Macy]

On Mar 23, 2:30 pm, m...@privacy.net wrote:

Robert Macy <m...@california.com> wrote:
The variable inductor is great for controlling resistive loads
especially in the 1kW to 10kW ranges.  ...you can actually make your
own if you want.

Is this called a "Variac"?

No, a variac is a tapped inductor with a wiper to make contacts along
the inductor's turns to provide a variable output voltage.. The input
voltage is applied to fixed points across the variac's fixed core
inductance. Then, by varying the tap for the output, the output
voltage can be adjusted.

The ones I've seen usually are rated for 100VA to 500VA, sometimes
1kVA, look like a torroid with bare turns exposed on the top edge.
They have a mechanically operated wiper [much like a rheostat, or
potentiometer] that by rotating taps into the inductor's windings. By
turning the knob the wiper goes from slightly above input voltage down
to zero volts. But, most of the ones I've seen have their last turns
near zero darkened, or worse, burnt, because the higher currents the
lower voltage often supplies, and for some reason the concept of
maximum current for a wire size just never comes to mind. People seem
to think that 500VA should be able to supply at least 100Watts at 5
volts, NOT!

I've seen several types of saturable core reactors. From memory, the
multi kW controllers from Northlake [again, from memory costs $150-
$250] looked like 3 phase transformers. The center core had the main
inductor winding on it and the two legs had the cross wound DC control
windings on them. Essentially, the two windings were wired to
subtract two large signals to get zero volts, but that never happens
very well and there are a lot of energetic signals appearing across
the DC control windings. The idea is that the DC windings were a huge
number of turns, so 100mAdc would saturate the legs, and, voila! no
inductance anymore.

The smaller types, varied a bit. some were cheerio sized with a hole
drilled through the side. I've made some in the lab using metglas
ribbon cores that I simply punched a hole through from outside to
inside to make a place to wind the figure eight.

You can make one from a high quality high voltage isolation
transformer, low loss type. Do you have any lying around and feel
like drilling it?

 

[Jeffrey D Angus]

Phil Allison wrote:

** It a HEATER - you fucking IMBECILE.

Do you eat with that same mouth?

Admittedly, if the heating element is Nichrome, it
doesn't have much of a temperature coefficient.

Jeff



--
“Egotism is the anesthetic that dulls the pain of stupidity.”
Frank Leahy, Head coach, Notre Dame 1941-1954

http://www.stay-connect.com

 

[Phil Allison]

"Jeffrey D Angus"

Phil Allison wrote:

** It a HEATER - you fucking IMBECILE.

Do you eat with that same mouth?

**Do you always REMOVE the context entirely when posting

great lumps of BULLSHIT like this ??

Admittedly, if the heating element is Nichrome, it
doesn't have much of a temperature coefficient.

** No fooling ??????????????

Now tell that BULLSHITTING TROLL Macy too.

An leave the FUCKING CONTEXT visible.

Idiot.



.... Phil

 

[Jeffrey D Angus]

Phil Allison wrote:

"Jeffrey D Angus"
Phil Allison wrote:

** It a HEATER - you fucking IMBECILE.
Do you eat with that same mouth?


**Do you always REMOVE the context entirely when posting

great lumps of BULLSHIT like this ??


Admittedly, if the heating element is Nichrome, it
doesn't have much of a temperature coefficient.


** No fooling ??????????????

Now tell that BULLSHITTING TROLL Macy too.

An leave the FUCKING CONTEXT visible.

Idiot.



... Phil

Ok, Do you eat with that same mouth Phil?

Jeff


--
“Egotism is the anesthetic that dulls the pain of stupidity.”
Frank Leahy, Head coach, Notre Dame 1941-1954

http://www.stay-connect.com

 

[petrus bitbyter]

"Robert Macy" <macy@california.com> schreef in bericht
news:39086479-0a6b-4906-ab22-e8a499725026@x12g2000yqx.googlegroups.com...
On Mar 20, 5:07 pm, m...@privacy.net wrote:

I have one of those 1500 watt radiator style portable
electric heaters. Love it

However, rather than the built in thermostat turning
the unit OFF?ON every 15 min's or so, I was thinking
it would be more efficient to use an SCR dimmer control
to vary the amt or power it gets?

Does anyone know of an SCR control hefty enough to
handle this kind of resistive heating load??

|2nd attempt to post this reply!
|
|use a saturable core reactor, which is a variable inductor controlled
|by a DC current through a secondary winding. Used to be made by
|Northlake near Chicago.
|
|The inductor, with 0 DC current has maximum inductance and 'starves'
|the resistive load down to 5 to 10%, then at maximum DC current the
|inductor is saturated and almost all the power makes it to the load.
|The transfer/control is monotonic, but very weird. L vs Idc
|
|The DC control winding is wound in a 'fgirue eight' pattern so that
|one adds, one subtracts with no net to the other winding, but due to
|the high number of turns, saturates the core locally. Saturating
|locally interrupts the magnetic field lines and is like opening up a
|large air gap in the core, thus the inductance drops to nil.
|
|I prefer radiant heaters, too. You can point them at yourself and sit
|very comfortably like in front of a fireplace. Used to have hot air
|blast heating but that made the room's air excessively hot in order to
|be comfortable when sitting. Then when you get up and move around you
|swelter. Whereas with radiant heat, the air can stay cool so when you
|move around, you're still comfortable. But those contact closures!!!
|very irritating if you went to sleep, they get very loud.
|
|The variable inductor is great for controlling resistive loads
|especially in the 1kW to 10kW ranges. ...you can actually make your
|own if you want.
|
|

Interesting solution though to me it looks like an overkill in space, weight
and cost. Modern electronics might not be that interesting but are very
effective.

petrus bitbyter

 

[Phil Allison]

"Jeffrey D Anus"
Phil Allison wrote:

** It a HEATER - you fucking IMBECILE.
Do you eat with that same mouth?


**Do you always REMOVE the context entirely when posting

great lumps of BULLSHIT like this ??


Admittedly, if the heating element is Nichrome, it
doesn't have much of a temperature coefficient.


** No fooling ??????????????

Now tell that BULLSHITTING TROLL Macy too.

An leave the FUCKING CONTEXT visible.

Idiot.


Ok, Do you eat with that same mouth Phil?

** Go get totally fucked

- you pathetic pedant & self appointed net cop TWAT.



.... Phil

 

[William Sommerwerck]

Wheee! This "Phil Allison" ride is a great thrill, eh?
I see they finally fixed it so that it works reliably now.
Any response gets a torrent of abuse ...

No, any response he doesn't agree with. He can be quite courteous, if you
don't say something he finds insufferably stupid.

 

[David Nebenzahl]

On 3/23/2010 4:03 PM Phil Allison spake thus:

"Jeffrey D Anus"

Phil Allison wrote:

** It a HEATER - you fucking IMBECILE.
Do you eat with that same mouth?

**Do you always REMOVE the context entirely when posting

great lumps of BULLSHIT like this ??

Admittedly, if the heating element is Nichrome, it
doesn't have much of a temperature coefficient.

** No fooling ??????????????

Now tell that BULLSHITTING TROLL Macy too.

An leave the FUCKING CONTEXT visible.

Idiot.

Ok, Do you eat with that same mouth Phil?

** Go get totally fucked

- you pathetic pedant & self appointed net cop TWAT.

Wheee! This "Phil Allison" ride is a great thrill, eh? I see they
finally fixed it so that it works reliably now. Any response gets a
torrent of abuse ...


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"