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??
Yeah that would work also....
Thing is I was hoping it possible to find such a control for maybe $30 or so.....as the dang heater only cost $40. lol
Anyway...... just thought controlling heat output that way (vary power) better than on/off thermostat.
A TRIAC lamp dimmer is PWM of sorts since it passes only a portion of the incoming sine wave. These are readily available for at least 1200 Watt loads. I assume this heater has no fan.
How much improvement are you expecting? You're gonna use up the same number of electrons to produce the same amount of heat. If the thermal hysteresis is large, you might argue that you get a tiny gain from the reduced maximum temperature via conduction losses thru the walls... but I expect it's less than the loss of a PWM controller... for a typical setup. Yes, the controller produces heat that you can use...just ain't worth the trouble for the minuscule gain you MIGHT get.
A light dimmer with this capacity ain't gonna be high-volume/cheap. No reason it couldn't be, except for volume...
You don't say how long it runs every 15 minutes. Hook two in series.
Bottom line...relax and enjoy the heat. Some problems don't need to be solved.
On 3/20/2010 4:07 PM snipped-for-privacy@privacy.net spake thus:
Or (maybe) better yet, how about some kind of PWM control? Wouldn't that be even more efficient (the control device is either on or off, so little thermal losses)? Just an idea ...
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On 3/20/2010 5:01 PM snipped-for-privacy@privacy.net spake thus:
Another idea, really quick and cheap: how about just a diode in series (or maybe several diodes in parallel)? That would cut the power in half. I haven't looked but surely you can get some rectifiers that would handle it, say 250 PIV and enough current to handle the heater.
-- You were wrong, and I'm man enough to admit it. - a Usenet "apology"
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
"isw"
** But there are now two heaters in series, R is doubled so the power is half..... Phil
But there are two heaters. Two times 1/4 = 1/2.
schreef in bericht news: snipped-for-privacy@4ax.com...
Ever build a thing like that as I could not find it on the market at the time. Used a 555, a dual pot and an SSR that could handle over 250Vac/20A. The SSR had a build in zero cross detector so I could switch on between 1 and 100 halfcycles within a 50 cycles period. Worked as advertised though it was not very cheap mainly caused by the price of the SSR.
petrus bitbyter
The on/off cycling of the device is not only for ambient temperature, but is also for device safety. The unit will cycle on and off until the thermostat temperature set point is reached.
Why not use 4 heaters in series? Or maybe even 8 or 12 or 16?
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?
Correct.... no fan at all!
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.
Don't want to do that...... just need one heater
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.
-- Lead free solder is Belgium's version of 'Hold my beer and watch this!'
I've only had one thing where the contacts wore out and that was decades old. Not counting engine ignition points.
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.
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.
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