General HVAC Questions
After some discussion with my dad I decided to post a question here regarding several topics. We live in Dallas.
1. He believes that it is best to leave the central fan running all of the time. His claim is that doing this will result in the heat or a/c cycling on less. Does running the fan all of the time have any impact?
2. Any time he leaves the house for work he puts the a/c very high and then when he returns from work cranks it down. I told him he was better off leaving it alone, that it ends up running longer when he cranks it down than it would have had he left it alone.
3. He also refuses to use ceiling fans, except for the room he is in. I said that, in my opinion, it is best to leave ceiling fans running which helps circulate air throughout the house.
Thanks for your comments.
its a preferance lots of people leave the fan on all the time. i cant say for sure if it helps or doesnt .
3 Ceiling fans do not col the air, but they do have a cooling effect on humans. If noone is in the room the power is being wasted.
questions asked, answers received, ignorance abated
Leaving fan on in summer is a better option then it's in winter. Human body feels better when air is circulating around it when it's hot. But when u r trying 2 heat a space air circulation doesn't feel that great unless u live in a very dry area and u get a humidifier installed which would run with fan being on then i would recomend leaving fan on in winter.
its ok to leave the blower fan on in the winter it will cuase a more even temp through your house. In the summer it is very bad causes high humidity the water on your coil and in your pan will be picked up by the air flow. Blower on in winter will cost electricity and wear your motor.
Drastic changes in the thermostat cost massive amounts of energy to get the house back under control a typically (this should be true for your area) it is best to set it in one temp and leave it alone.
Ceiling fans are pretty much useless if not being occupied. cost energy and wears the motor if you have high ceilings in the summer it will draw dawn hot air cuasing you to use more air conditioning. In the winter doesnt matter but i would use the blower before i wasted alot of fans for nothing.
Leaving the fan one is somtimes good for helping balancing out temperture between rooms. Setting back a thermostat does save energy.
From the American Council for an Energy-Efficient Economy
1. Reduce excessive use:
Use air conditioning only when ventilation is inadequate.
Set the temperature up when leaving the house.
Always keep all doors and windows closed when operating an air conditioner.
Don’t cool unoccupied rooms (but don’t shut off too many registers either, or it will put pressure on the system).
Minimize indoor humidity by running hot-water appliances in the evening and by showering with the exhaust fan on.
If your room air conditioner has an outside air option, use it sparingly.
2. Increase your comfort range by using fans.
With a ceiling fan, you will probably be comfortable with the thermostat set at about 78°F. Each degree you are able to raise the thermostat, you will save 3–5% on air conditioning costs.
3. Clean the air filters on room air conditioners monthly.
They should never be allowed to get dirty enough to impede air flow, as this could cause damage to the unit. The condenser should be cleaned by a professional every other year, or even yearly in dusty locations.
4. Hire a professional technician to inspect, clean, and tune your system every 2-3 years.
During service of your unit, its refrigerant may need recharging. This correction can improve system efficiency by 20%.
The technician should measure airflow over the indoor coil. Correcting airflow rates can improve efficiency another 5–10%.
Regardless of how well tuned it is, the system will not operate efficiently if the duct system is in poor condition. Proper sealing and insulation can reduce cooling energy use by 10–15%.
5. Cool with air movement and ventilation
Fan operation uses less energy than air conditioning and can be adequate for attaining desired comfort levels unless you live in a very humid climate.
Ceiling fans. Ceiling fans cool by creating a low-level “wind chill” effect throughout a room. As long as indoor humidity isn’t stifling, they can be quite effective. Just remember that a fan cools people — it doesn’t actually reduce room temperature — so turn it off when you leave the room. Look for ENERGY STAR rated ceiling fans.
House fans. Unless you live in a very humid climate, installing a large fan in your top-floor ceiling is a very effective way of cooling your whole house down without central AC. These fans suck air through the house, inducing a strong draft in rooms where windows are open as it pulls cooler, outdoor air inside. Check with your local home improvement retailer about available products and installation.
From the Department of energy
Through proper use of a programmable thermostat (using the 4 pre-programmed settings) you can save about $150* every year in energy costs.
Rules of Thumb for Proper Use:
Keep the temperature set at its energy savings set-points for long periods of time (at least eight hours), for example, during the day, when no one is at home, and through the night, after bedtime.
All thermostats let you temporarily make an area warmer or cooler, without erasing the pre-set programming. This override is cancelled automatically at the next program period. You use more energy (and end up paying more on energy bills) if you consistently “hold” or over-ride the pre-programmed settings.
Units typically have 2 types of hold features: (a) hold/permanent/vacation; (b) temporary. Avoid using the hold/permanent/vacation feature to manage day to day temperature settings. “Hold” or “vacation” features are best when you're planning be away for an extended period. Set this feature at a constant, efficient temperature (i.e. several degrees warmer temperature in summer, several degrees cooler during winter), when going away for the weekend or on vacation. You'll waste energy and money if you leave the “hold” feature at the comfort setting while you're away.
Cranking your unit up to 90 degrees or down to 40 degrees, for example, will not heat or cool your house any faster. Most thermostats, including ENERGY STAR qualified units, begin to heat or cool at a programmed time, to reach set-point temperatures sometime thereafter. Units with adaptive, “smart,” or “intelligent” recovery features are an exception to this rule — they reach desired temperatures by the set time, since they use formulas that are based on your historical use.
Install your unit on an interior wall, away from heating or cooling vents and other sources of heat or drafts (doorways, windows, skylights, direct sunlight or bright lamps).
Many homes use just one thermostat to control the whole house. If your home has multiple heating or cooling zones, you'll need a programmed setback thermostat for each zone to maximize comfort, convenience and energy savings throughout the house.
Don't forget to change the batteries each year. Some units indicate when batteries must be changed.
"During service of your unit, its refrigerant may need recharging. This correction can improve system efficiency by 20%. "
Where are they coming up with this? It's a sealed system not a battery. The refrigerant doesn't go flat.
Have you hugged the Earth today?
Donny Baker rules
leaving the fan on gives you more even tempreture control thrughout the home.
eliminating warm spots in summer or coolspots in winter
i agree w/ B.G...if stirring up the air you do have a balancing effect, with vaulted ceilings or sun hit rooms...the furniture becomes a load with the heat content and the load will become apparent in power consumed to remove the heat. volt x amps= watts...1 more thing...amp out a ceiling fan when the rotation is against the ceiling (within a short amount of distance between blade and ceiling)
versus opposite rotation. u will notice if the rotation is reversed the motor will not work as hard. thus pulling less amps...;~)
in the industry, occupied and none occupied space while still circulating the air
is also used in commercial applications (while economizers take advantage of low outside ambient temperatures, mixing fresh colder outside air can also lessen our customers monthly elect bill...over kill maybe but a understanding of energy efficiency can start at the panel, amping out all circuits and adding up how much energy is consumed with a simple formula... E/I x R
if you think any of these conversations are interesting check this link out
Last edited by sumdumguy; 11-24-2007 at 04:25 PM.
Reason: a career path for the youngster
1. You do not want the blower to run all of the time in a humid environment. Running the blower after the system turns off adds humidity right back into the structure from water in the drain pan and water on the coil.
Originally Posted by misterjw
2. Reports have shown using a setback thermastat saves energy when programmed correctly and left alone. Bumping up only a few degrees can save you, as long as you do not bump it up too high where it has to run a long time to cool the house back down.
3. Running ceiling fans gives you an evaporation effect on your skin which gives you a sese of coolness. It all depends on how many fans you have running as to whether you are actually saving anything in the longterm.
in a nutshell
the bottom line is:
#1 you obviously live in a humid area so running the fan all the time would rehumidify your dad's house.
#2 digital thermostat will do much good and in the long run save money if properly programmed and not tinkered with.
#3 ceiling fans. run them to make you feel cooler. but keep in mind you need to run the AC enough to keep the house dehumidified.