There is a discussion not long ago about this, but i did not follow all the threads.
Questions:
Someone is running the air conditioner 24/7 down to 70 degree. So, i added a micro controlled relay to duty cycle it.
he threads.
much less efficient running it 20 minutes on and 10 minutes off.
unning all the time?
ed a micro controlled relay to duty cycle it.
The question doesn't make a whole lot of sense. If the A/C is trying to run= all the time then it is undersized for its loading, so modulating the duty= cycle will not allow the interior temperature to reach setpoint. Generally= , if you take your heat infiltration rate and divide it by the cooling capa= city of your unit, that gets you the duty cycle.
the threads.
w much less efficient running it 20 minutes on and 10 minutes off.
running all the time?
dded a micro controlled relay to duty cycle it.
un all the time then it is undersized for its loading, so modulating the du= ty cycle will not allow the interior temperature to reach setpoint. General= ly, if you take your heat infiltration rate and divide it by the cooling ca= pacity of your unit, that gets you the duty cycle.
The point is that i don't want it to run down to 70, but i don't want to ke= ep changing the thermostat or arguing. I want to duty cycle it to 78, even= when set to 70. I put in a uC relay between the thermostat and A/C unit.
8
threads.
much less efficient running it 20 minutes on and 10 minutes off.
running all the time?
a micro controlled relay to duty cycle it.
all the time then it is undersized for its loading, so modulating the duty cycle will not allow the interior temperature to reach setpoint. Generally, if you take your heat infiltration rate and divide it by the cooling capacity of your unit, that gets you the duty cycle.
changing the thermostat or arguing. I want to duty cycle it to 78, even when set to 70. I put in a uC relay between the thermostat and A/C unit.
Why not add another (hidden) thermostat and disconnect the one that's being tampered with. ;-)
Duty cycle will not change the minimum temperature, rather it will change the minimum differential between outside and inside temperature. So, if it will acheive 78°F when the outside temperature is 105°F, then it should cool to meat locker temperatures on a more normal day.
As someone else suggested, a second thermostat (eg. a second one in series with the first one) set to 78°F will do what you say you want.
BTW, _why_ do you want to do this? For creative work (eg. engineering), office temperatures in the ~70°F= 21°C range are optimal for productivity, at least for males (women tend to feel cold at those temperatures and require sweaters, warmer zones or local space heaters). Productivity is the end goal, right- who cares about a few dollars more in energy costs?
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
mal
Where did you get that crazy number? At 50% RH, 70oF feels like ice, and 75= oF is more in the comfort zone, which feels like nothing, neither hot nor c= old.
is more in the comfort zone, which feels like nothing, neither hot nor cold.
What? 70°F/50%RH feels pretty much neutral to muggy. 75°F/15%RH is just cool enough to feel pleasant. 110°F/5%RH will freeze your butt off when you climb out of my swimming pool ;-) ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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My biggest worry is burning out the compressor, with it running non-stop al= l the time. It's about 105F at 16% RH outside. I feel comfortable enough = at 78F, and cold at 70F
is more in the comfort zone, which feels like nothing, neither hot nor cold.
Here's one study:=
Creative work requires temperatures at the lower end of the curve. Also, engineers create more heat than clerical workers doing the same kind of sedentary work. Our brains burn more fuel, so more A/C capacity is required.
Anyway, IME, there are people with preferences from 18°C to 25°C (+/-6F) , which pretty much guarantees that a significant fraction of people in an office will be at least a bit unhappy.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Some of the newer AC units use variable speed compressors and condenser fans (VFDs). With suitable controller intelligence, these units can 'tweak' their cooling to provide a steady stream of conditioned air rather than the cycling on and off of older style systems.
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ 100 buckets of bits on the bus 100 buckets of bits You take one down, and short it to ground FF buckets of bits on the bus
So, does it shorten life of the compressor by cycling on and off? If so, i would be forced to upgrade to newer system soon.
would be forced to upgrade to newer system soon.
Upgrade your brain. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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75oF is more in the comfort zone, which feels like nothing, neither hot no= r cold.your-productivity.aspx
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If it works for you go with it. I dunno about creativity or how you would e= ven define it, but I do know a little bit about concentration. That is more= of an out of body experience where, within reason, the work environment do= es not seem that important, and time flies, looking at the clock expecting = five minutes to have passed and seeing that it has been more like two hours= or something like that.
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75oF is more in the comfort zone, which feels like nothing, neither hot = nor cold.Speak for your self injun. Me roundeyes, likem 70 F just fine.
?-)
condenser fans
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so, i would be forced to upgrade to newer system soon.
Pretty much only if the cycle time is too short like
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75oF is more in the comfort zone, which feels like nothing, neither hot no= r cold.The RH makes all the difference in the world- just a few percentage points = really make a difference. I'm sitting here now with two independent reading= s of temperature at 75oF and 49% RH, wearing a sweatshirt, and not even beg= inning to perspire. And I really don't care for warm temperatures either, b= ut at this RH if the temp goes any lower, which it could if unit is in A/C = only mode and outdoor temps go to low 70s-60s, I would have to put on even = more clothes. This is why all the modern thermostats have an RH setting, no= t just a reading, in addition to a temperature setting, because it makes a = HUGE difference.
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nd 75oF is more in the comfort zone, which feels like nothing, neither hot = nor cold.
s really make a difference. I'm sitting here now with two independent readi= ngs of temperature at 75oF and 49% RH, wearing a sweatshirt, and not even b= eginning to perspire. And I really don't care for warm temperatures either,= but at this RH if the temp goes any lower, which it could if unit is in A/= C only mode and outdoor temps go to low 70s-60s, I would have to put on eve= n more clothes. This is why all the modern thermostats have an RH setting, = not just a reading, in addition to a temperature setting, because it makes = a HUGE difference.
One last point is don't even bother with an RH adjustable system unless you= r structure is absolutely air tight, the thermostat will be running your te= mps at up to 5o below temperature setting trying to reach an impossibly low= RH for the leakage- if you're in a high humidity region. "The DOE=92s Building America=92s performance criteria include a recommenda= tion that =93Air leakage (determined by blower door depressurization testing) should be less than 0.25 cfm/ft2 (1.3 L/s per m2) of building enclosure surface area at a 50 Pa (0.2 in. w.g.) air pressure differential.=94
That depends on how frequently your system cycles and how your compressor is rated (starts per hour). Its an issue of temp rise in the motor due to starting current and how that will affect the motor's life.
If its within spec, system life will probably be determined by other factors. If its happening too often (due to an improperly sized system) you could increase the thermostat hysteresis (on and off points). Your comfort level will suffer somewhat, but you could squeeze a few more years out of the system.
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ In the beginning, there was nothing. And God said, "Let there be Light." And there was still nothing, but you could see it.
no answer, not enough data given.
OR it is max effecient when running, AND max effecient when off, therefore it is running at MAX effeciency.
Depends upon the failure rate of going on and going off
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I am doing 3 per hour. I believe most motor will do 6 to 8.
verse continuous heating running it all the time. My question is which is = worse.
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tI am doing 20 minutes on/off cycle for now, until the new controller is rea= dy. What i want is a password protected setting of max. and min temperatur= e. I don't really want them to change the central air too much. They can = always run the window air conditioner to the max, but they don't like the n= oise next to it.
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