You will have to seperate the motor from the heating element. Probabaly not
much differant in the efficency of either. I work on some scr type controls
that operate at 480 volts and 600 amps. We also have some that operate on
lower voltages, but the control circuits would cost much more than a truck
load of heaters like you have.
Simple... Connect a Diode ( of amperage for more than the heater wattage)
across the thermostat connections. This will cut the voltage in half to the
heating element. Connect the fan to the hot side of the thermostat so it
will still run at the lower heat output when thermostat is "open" "off". WW
On Mar 20, 6:04 pm, email@example.com wrote:
There is no difference in the efficiency. 100% of the electricity
will be turned into "heat" with either method.
The SCR approach simply means the unit turns on and off
60 times per second instead of every few minutes. It is also
necessary to build an interfact to it if you want to control the
temp with a thermostat.... Additionally, there will be some
interference generated on the power line by the constant
switching, which might even interfere with your radio or
That being said, it's a do-able idea. But just because an
idea can be made to work, it doesn't mean that it is a good
idea or that it has any real advantage over the existing way.
Think about it.... What grander, better thing will happen
if you go to that trouble?
Andy in Eureka, Texas
I don't want to control the heater with a thermostat at
all cause I come and go so much that I just turn the
unit off/on when leaving/coming.
I would turn thermostat all way up.....and control heat
with pulses from Triac
You would still use a thermostat to controll the heat, but the heat
would be more even as, if properly adjusted, the heater would be on
almost constant and there would not be great fluctuations.
A bit like the units that switch from 1 to 2 to 3 elements for low,
medium, and high - 500 watts each for 500, 1000, and 1500 watts.
There is a radiant heater made in Turkey and sold in North America
that DOES have variable heat output - and IIRC (only saw them once) it
does use an SCR type phase switching control.
*Most likely it won't be more efficient because the power not going to the
heater will be dissipated through the dimmer. Also the heating elements
will not function as well with reduced voltage. You may turn the voltage
down to 75%, but the actual heat output may be reduced to 25%.
Agree with Andy and John. I don't see what the real objective is
here regarding the stated goal of efficiency. The existing simple
thermostat is just a bimetalic switch that dissipates very little
energy. Less energy than the SCR will dissipate. But either way,
all that energy is heat that goes into the room anyway.
Also, the heat output is a function of the square of the voltage. So,
if you reduce the voltage to 75%, the power will be at 56%.
On Mar 21, 6:12 am, firstname.lastname@example.org wrote:
The heating element may be non-linear, so the current may not
be linearly reduced along with the voltage, and will be different...
I did some experiments with an old stove top burner which , the
small size, is 1000 watts when powered by 220V.....
I found that the current drawn was linear with voltage, which
that running it from 110V made it a 250 watt element.
However, light bulbs, for instance, are not linear, and the same
Just felt like typing --- it's easy enough to characterize your
if you have a voltmeter and a current meter.....
By the way, I have a great application for old stove burners mounted
on a metal paint bucket filled with sand..... Really good heaters
don't put out enough light to keep you awake at night.... and keep
your coffee warm.....
Andy in Eureka, Texas
Good point..... could be the case!
I realize it may NOT be worth pursuing.....especially
if there does not exist off shelf Triac control at low
But since I come and go so much.... I turn the little
heater off and on a lot.....so a thermostat does little
good for me.....and was thinking a Triac would allow me
to "tweak" very small increments of heat....and then
just keep at that setting.... and turn heater off/on
Probably not worth messing with..... but it was an
You can buy a 2000W dimmer. I have one, and I use it to control a
1500W tungsten light bulb (as part of a light bulb collection, nothing
more). They were hard to find on the web a few years ago, but search a
little and you'll get one. If you want I can look at the brand name on
Depends what "voltage" is being discussed. It reduces the RMS voltage.
RMS voltage is the voltage displayed by a typical meter. Attach a load
to a dimmer and then connect your meter to the load. You will note that
the displayed voltage does drop as you lower the dimmer. RMS is used
because it approximates the DC value which is what we need to perform
easy power calculations.
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