Hi, I'm working on a project and need a constant heat source (no open
flame) so an electric burner would be best, but from what I've read a
vast majority of them cycle on and off, is there a way to modify them
to make them run constant? like remove a resistor or something? this is
very similar to what I'm talking about

http://tinyurl.com/hoylu

any help would be awesome, thanks.

vairox wrote:
Hi, I'm working on a project and need a constant heat source (no open
flame) so an electric burner would be best, but from what I've read a
vast majority of them cycle on and off, is there a way to modify them
to make them run constant? like remove a resistor or something? this is
very similar to what I'm talking about

http://tinyurl.com/hoylu

any help would be awesome, thanks.


I'd expect any such source to use a thermostat to provide the "cycling"
- removing power from the element when the set temperature is reached,
then restoring power when the temperature drops below that temperature.
Often an embedded bi-metallic strip type device. If the device has a
variable temperature setting, this can be confirmed to a high degree of
confidence by adjusting the temperature setting with the device off, if
you get get the temperature setting down to room temp, and hear/feel the
contact open then you can be pretty sure it's a bi-metallic strip.

To bypass this type of device, simply short the terminals across the device.

Of course there could be other devices at play here, especially as the
cost of electronic controllers has dropped.

Daft question?, why do you want to circumvent the control system that
should be there to maintain a constant temperature?, what you propose is
a device that's going to heat *something* until the point at which the
heat provided by the pad is matched by the heat being dissipated by the
*something*. Or *something* catches fire, melts, or goes bang.

On Tue, 08 Aug 2006 07:22:30 +0100, Mike Dodd wrote:

Daft question?, why do you want to circumvent the control system that
should be there to maintain a constant temperature?

Maybe because a cyclic control system has pretty crap short term
temperature control. The long term mean can be quite good but the high
and low excursions whne the power is on/off can be huge.

As to the OPs problem get a hot plate, bypass the built in thermostat and
feed the thing via a suitably rated variac or electronic dimmer (power
controller). There would have to be some trial and error to calibrate the
variac/dimmer to temperature and that calibration would vary with what
ever is on the plate as well but for the same thing I should imagine
fairly repeatable.

There maybe electronic power controllers that have an external temp
sensor that one could bung in the pan but I've not looked.

--
Cheers
Dave. pam is missing e-mail

In article .com,
vairox wrote:
Hi, I'm working on a project and need a constant heat source (no open
flame) so an electric burner would be best, but from what I've read a
vast majority of them cycle on and off, is there a way to modify them
to make them run constant?

Then it won't be a constant heat source. It will be influenced by
surrounding temperature and load, etc. What you apparently need is a
device which maintains an exact temperature. If you remove the thermostat
from most such devices it will self destruct.

If you'd give the application it might help.

--
*I didn't drive my husband crazy -- I flew him there -- it was faster

Dave Plowman London SW
To e-mail, change noise into sound.

"vairox" wrote in message
oups.com...
Hi, I'm working on a project and need a constant heat source (no open
flame) so an electric burner would be best, but from what I've read a
vast majority of them cycle on and off, is there a way to modify them
to make them run constant? like remove a resistor or something? this is
very similar to what I'm talking about

http://tinyurl.com/hoylu

any help would be awesome, thanks.


http://homedistiller.org/control.htm might have ideas for the sort of thing
you want.

H

Mike Dodd wrote:
vairox wrote:

Hi, I'm working on a project and need a constant heat source (no open
flame) so an electric burner would be best, but from what I've read a
vast majority of them cycle on and off, is there a way to modify them
to make them run constant? like remove a resistor or something? this is
very similar to what I'm talking about

http://tinyurl.com/hoylu

any help would be awesome, thanks.


I'd expect any such source to use a thermostat to provide the "cycling"
- removing power from the element when the set temperature is reached,
then restoring power when the temperature drops below that temperature.
Often an embedded bi-metallic strip type device. If the device has a
variable temperature setting, this can be confirmed to a high degree of
confidence by adjusting the temperature setting with the device off, if
you get get the temperature setting down to room temp, and hear/feel the
contact open then you can be pretty sure it's a bi-metallic strip.

To bypass this type of device, simply short the terminals across the device.

Are you trying to hospitalise the OP?

Do not wire over the stat. Use a series impedance of some kind in
series with the heating element, keeping the fan on full mains voltage,
and set the stat to above the temp you want to get out. Use a
thermometer to measure what youre getting and adjust the impedance to
get the desired temp. This will give a stable temp once you've run it
for 5 minutes or so to stabiilse the temp of all the parts.

Suitable series impedances: _very_ big resistor, light bulbs,
capacitor(s), or suitably rated inductors. If tht heating elemnt is low
power (500w), a standard dimmer will work nicely.


NT

lots of replies! I'm trying to distill alcohol without an open flame,
ethanol boils off at 78.4C (174F) and I don't want a source that is
going to constantly turn on and off because it will lower the temp and
then have to get back to where it was and cycle again and again... I
was hoping there was some sort of heating device that you just turn to
whatever temp you want and it stays there... maybe one of those $800
lab hot plates I don't know.

it doesn't seem like it would be all that hard to have an electric hot
plate that stayed at a certain temp, but then again I'm no electrician.

vairox wrote:
lots of replies! I'm trying to distill alcohol without an open flame,

why didn't you say so !

http://cgi.ebay.co.uk/1500W-Cast-Iro...QQcmdZViewItem

there are others out there ;-)

http://www.moonshine-still.com/page2.htm

hth

"vairox" wrote in message
oups.com...
lots of replies! I'm trying to distill alcohol without an open flame,

allegedly, your local Customs & Excise office - look under HMCR in the
yellow pages can supply all the advise you'll need.

ethanol boils off at 78.4C (174F) and I don't want a source that is
going to constantly turn on and off because it will lower the temp and
then have to get back to where it was and cycle again and again... I
was hoping there was some sort of heating device that you just turn to
whatever temp you want and it stays there... maybe one of those $800
lab hot plates I don't know.

it doesn't seem like it would be all that hard to have an electric hot
plate that stayed at a certain temp, but then again I'm no electrician.


One of the phenomena of _all_ control systems is called hysterisis:
What you've described as "going to (constantly) turn on and off because it
will lower the temp and then have to get back to where it was and cycle
again and again"

A system will ramp up to a control value, perhaps maintain that value then
fall off to a lower value, perhaps maintain this lower value before ramping
back up to the top value. Any temperature maintaining system will exhibit
hysterisis. 'Tight' control loop systems _might_ achieve 78.4 deg but it'll
be 78.4 +/- a 'bit'. Roughly; the size, and direction, of 'a bit' is going
to become more expensive the smaller 'a 'bit' is.
78.4 (0 / -2) would be cheaper than 78.4 (+0.001/-0.001). You seem to desire
a 'perfect' system with no hysterisis that will heat a fluid to 78.4 +0.000
/-0.000. But as the old saying runs; anything is possible given enough time
and money.

BTW; why?

--

Brian

vairox wrote:
lots of replies! I'm trying to distill alcohol without an open flame,
ethanol boils off at 78.4C (174F)

then all these replies have been a waste of time.

NT

"vairox" wrote in message
oups.com...
lots of replies! I'm trying to distill alcohol without an open
flame,
ethanol boils off at 78.4C (174F) and I don't want a source that is
going to constantly turn on and off because it will lower the temp
and
then have to get back to where it was and cycle again and again... I
was hoping there was some sort of heating device that you just turn
to
whatever temp you want and it stays there... maybe one of those $800
lab hot plates I don't know.

it doesn't seem like it would be all that hard to have an electric
hot
plate that stayed at a certain temp, but then again I'm no
electrician.


Well when I was doing that some 30 years ago (me being a process
control engineer at the time, and my flatmate an industrial chemist) I
designed and built a pulse width modulated driver for a normal kettle
element which was part of a control loop based on a type 'k'
thermocouple located at the bend point of our still. Worked
splendidly - the heater element maintaining a steady state of light
boiling. Discard the first few drops distilled - they contain the
ketones that give you a hangover !!!!

AWEM

In message .com,
vairox writes
lots of replies! I'm trying to distill alcohol without an open flame,

Well, people have been doing it (with an open flame) for hundreds of
years, shouldn't be that difficult

The temperature of the heat source isn't SO important, the temperature
of what you are boiling should remain at each component's BP while it
boils off

Why not buy a fractionating column if you're that bothered

--
geoff

wrote:
Mike Dodd wrote:
vairox wrote:

Hi, I'm working on a project and need a constant heat source (no open
flame) so an electric burner would be best, but from what I've read a
vast majority of them cycle on and off, is there a way to modify them
to make them run constant? like remove a resistor or something? this is
very similar to what I'm talking about

http://tinyurl.com/hoylu

any help would be awesome, thanks.

I'd expect any such source to use a thermostat to provide the "cycling"
- removing power from the element when the set temperature is reached,
then restoring power when the temperature drops below that temperature.
Often an embedded bi-metallic strip type device. If the device has a
variable temperature setting, this can be confirmed to a high degree of
confidence by adjusting the temperature setting with the device off, if
you get get the temperature setting down to room temp, and hear/feel the
contact open then you can be pretty sure it's a bi-metallic strip.

To bypass this type of device, simply short the terminals across the device.

Are you trying to hospitalise the OP?


Aha, I see you failed to quote my post that detailed the likely result
of what I suggested ("catches fire, melts, or goes bang"), despite
having clearly answered the OP's *specific* question as to how to modify
them to make them run constant.


Do not wire over the stat. Use a series impedance of some kind in
series with the heating element, keeping the fan on full mains voltage,
and set the stat to above the temp you want to get out. Use a
thermometer to measure what youre getting and adjust the impedance to
get the desired temp. This will give a stable temp once you've run it
for 5 minutes or so to stabiilse the temp of all the parts.

Suitable series impedances: _very_ big resistor, light bulbs,
capacitor(s), or suitably rated inductors. If tht heating elemnt is low
power (500w), a standard dimmer will work nicely.



Now that the OP has provided the proper statement of the problem, we can
progress. To be honest, at the temperature that he's citing I'd actually
recommend a variable-temperature immersion coil, into an oil bath, into
which the distillation vessel is submerged. That should provide a
reasonably controllable system, which, once up to temperature, the *slow
* addition of alcohol to the distillation vessel, and the relatively
slow rate at which the achohol boils off should not unbalance significantly.

The message
from "Brian Sharrock" contains these words:

'Tight' control loop systems _might_ achieve 78.4 deg but it'll
be 78.4 +/- a 'bit'. Roughly; the size, and direction, of 'a bit' is going
to become more expensive the smaller 'a 'bit' is.

And anyway, 78.4°C is only the standard boiling point. If the air
pressure isn't 1Bar that day then it'll wander anyway.

I'd make a bain-marie and warm that gently - the fractions will come off
one by one anyway provided the temperature's raised gradually enough. A
large mass of water in the outer jacket will make this easier.

--
Skipweasel
Pay no attention to that man behind the curtain.

On 8 Aug 2006 11:26:06 -0700 someone who may be "vairox"
wrote this:-

I'm trying to distill alcohol without an open flame,

The still you can see at
http://www.maltmasterclass.co.uk/still.htm#top and
http://www.maltmasterclass.co.uk/ is usually run from a "Baby
Belling" heating ring, with the on/off control that you spurn. It
distills alcohol very well. Remember that the thermal inertia of the
still and its contents will moderate temperature fluctuations.

The still can also be run on gas and "traditional" fuels like peat,
but electric is less messy and avoids the potential problems of an
open flame.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:

The still can also be run on gas and "traditional" fuels like peat,
but electric is less messy and avoids the potential problems of an
open flame.

Such as smoke rising through the trees and attracting the Revenue men?

John
--
John White,
Electrical Contractor

The message
from John White contains these words:

Such as smoke rising through the trees and attracting the Revenue men?

The revenue don't mind you distilling - provided you pay the duty.

--
Skipweasel
Pay no attention to that man behind the curtain.

On Wed, 09 Aug 2006 13:02:08 +0100 someone who may be John White
wrote this:-

The still can also be run on gas and "traditional" fuels like peat,
but electric is less messy and avoids the potential problems of an
open flame.

Such as smoke rising through the trees and attracting the Revenue men?

Ha, ha.

One of them did once see the still and ask if there was a licence
for it. When we said, "yes", she did not ask to see it. The licence
was in a filing cabinet near the still.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Wed, 9 Aug 2006 14:56:43 +0100 someone who may be Guy King
wrote this:-

The revenue don't mind you distilling - provided you pay the duty.

Only if the still is above a certain size. Below that they are not
keen.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:

On Wed, 9 Aug 2006 14:56:43 +0100 someone who may be Guy King
wrote this:-


The revenue don't mind you distilling - provided you pay the duty.


Only if the still is above a certain size. Below that they are not
keen.

They probably don't care either way so long as you don't sell it! ;-)


--
Cheers,

John.

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