Hot answers tagged

26

A thermostat basically just energizes the individual circuits (G (fan), W (heat), Y(cool) ) which in turn (via the furnace controller) powers a relay which provides line voltage to the actual units (like the fan or A/C. In the case of heat, it instructs your furnace to open the valve supplying gas). R (or Rh and Rc) provides the 24VAC power. To turn on ...


20

There are many options, but concrete is very dense and makes a great heatsink. You can try insulating and air-conditioning the inside, but this approach is costly, energy-intensive and overall wasteful. If you have room, I suggest planting a deciduous tree between the building and the path of the sun. During the warm season, the trees leaves will shade ...


14

The first thing you should do is insulate the roof. Even just gluing sheets of Celotex or your local equivalent will make a huge difference, though installing it in a proper ceiling would be better. This will reduce the solar gain from the roof. Depdning on the material, painting the roof white could also help quite a bit. The walls will also allow a fair ...


13

To be clear -- Concrete does not cause it to get warm. Concrete is a very good thermal buffer - it resists changes in temperature. This is a highly desirable trait in a passively heated and cooled home. Because if the home is cool, it will stay cool despite the sun. If the home is warm, it will stay warm despite the cold. Insulation on the outside of ...


12

The logic involved is much more complex. Right now the logic is simple: if AC Mode and it's too hot, turn on AC, else turn off AC if Furnace mode and its too cold turn on furnace, else turn off furnace But the determination of when to switch between heating and cooling modes is much more complex - otherwise the ac would kick on, and it would get too cold,...


11

I assume you mean the roof is exposed to the sun...and that in turn is heating your ceiling? If so, options: make sure the roof is reflective (white/metallic) rather than a dark color (which absorbs heat) make sure the roof is insulated If the roof can support a green/planted roof, consider that. plant trees to shade the roof (obviously may take a few ...


11

Keeping what is effectively a greenhouse cool in the summer is a heavy workload for any AC system. Your best bet is to prevent solar heat gain by blocking the light. Doing this with an opaque shade on the exterior will be the most effective option, though window tints or interior shades would also help. Of course anything that reduces heating in the summer ...


9

If you open both the top and bottom about 3" the hot air goes out the top and cooler air comes in the bottom.


9

A dehumidifier is about the same as a window AC unit with both parts in the house, for most purposes. They draw just as much power as an A/C unit of similar size (or more if they happen to be old and inefficient.) Given that the required energy labeling on A/C units tends to promote a degree of of paying attention to that, and it's much less clear on ...


9

I think you're overestimating the energy benefits you can get from window films. Those are primarily indicated to reject ultraviolet radiation that can increase fading of indoor materials. You're also mistaken if you think that during the winter the heat gain from sunshine on poorly insulated windows can make up for the heat that is radiated back out of ...


7

If your current AC is not adequate to extend to the garage area, then a ductless mini-split wall mounted AC unit is probably ideal for your situation. Once installed, you'll likely exceed the $1500 budget, but I think it's the best of the options. You wall mount half of the unit inside the home and run the cooling lines through the wall and out to an ...


7

For the record, I tried it out myself. I installed the Cool-N-Save system on a 4-ton A/C unit that was scheduled to be replaced in three months. After that three month period in the middle of the summer, the positive effects of the system were negligible at best, and probably detrimental. There were no detectible savings in cooling costs nor increase in ...


7

Generally one opens the bottom window, simply because it's easier. The features of the window tend to be designed with that in mind: the screen (if it is original to the window) will usually have a bit of extra fill along the top edge where it meets up with the upper window's bottom edge if there is a partial open lock (that prevents complete opening) it'...


7

You haven't mentioned what sort of fixture these bulbs are in, but this sounds like a classic case for compact fluorescent lights (CFL). Efficiency in light bulbs boils down to "for a given amount of power running through the bulb, how much is turned into light and how much is wasted as heat?" Fluorescent bulbs are much more efficient than incandescents; ...


6

Mineral build-up is going to be dependent on your water. Do you have a Water Quality Report? Mine looks like this: http://www.acwd.org/story_detail.php5?story_id=157 Hard water starts around 10 grains per gallon or 170 ppm. In other words, 1 liter of water will have 0.17 grams of calcium/magnesium. I didn't see any water usage estimates for coolnsave aside ...


6

A 60-watt incandescent puts out about 800 lumens of light. A 100-watt incandescent puts out about 1600 lumens. Your 10 60 watters put out about 8000 lumens total. It'll only take 5 100-watt bulbs to equal that. 60 * 10 = 600 watts heat. 100 * 5 = 500 watts heat. So, if the sockets can handle it, your room will be a little cooler if you switch to using 5 ...


6

What about an attic vent fan such as this one? It has a thermostatic control. Separate shutters are also available such as these. They open based on the air pressure generated by the fan. You would need to create "in" vents, preferably placed low on several walls to allow full air flow. These could be either fixed or shuttered, depending on whether you ...


6

I would say a dehumidifier would not be a more efficient choice for summer comfort than turning down the thermostat on an A/C. Sure, the delta-T across exterior walls would drop, so somewhat less heat would seep in from outside, but as was already mentioned, the A/C then has to remove the dehumidifier's additional heat from the home (100% of the input power ...


6

There is an optional add-on part for HVAC systems called an economizer. An HVAC economizer is a dampered vent designed to save energy and give the cooling system a break. Sensors within the economizer compare the outdoor temperature and humidity with that inside the building. –Google When you call for cooling, the unit decides if it needs to run the AC ...


6

I have about 50 55-gallon drums stacked in my basement, all filled with water. They are stacked one on top of the other (bottom row/top row) along our north basement wall. I have two in floor-mounted fans, one pushing, one pulling, mounted in the ground-floor joist cavity (from above they just look like floor mounted cold air returns). During the day, the ...


5

There are programmable thermostats that automatically switch from heat to a/c and to heat again. Some Honeywell thermostats, such as the 8000 Series, have 'auto' setting where you can program the Heat temperature and the cool temperature and the thermostat will automatically switch from heat to cool. I don't know how long they've been on the market though.


5

Whenever it's cooler outside than it is inside. But you have to factor into the equation the humidity, breeze, impact of sunlight since you can't keep the blinds down, etc. And if you open the windows, the humidity that enters the home takes time to be removed by the AC. Personally, I wait until the outside high temp is about 5F above my target temp, and ...


5

For central A/C, you'll need ducts and vents. Once you have the ducting in place anyway, you might as well use it for both your heating and cooling. For a three floor house, you definitely want some kind of zoned system, with a thermostat on each floor. (I wish my 2-floor house was zoned.) You may want multiple cooling systems, or maybe one system with ...


5

I have been experimenting with using an old mosquito misting system to mist around one of my AC condensers. It does seem to make a small difference in energy consumption and reduce register temperature by around 1 degree. Not much but enough to help when the system is running constantly when we have parties at the house. The red circle on the attached ...


5

Much like DA01 said, a ceiling fan generally acts to circulate air within a particular space of the home. This evens out the temperature of the air in the room by preventing "stratification" (where the air settles into noticeable "layers" so it's warmer at head height than at the floor), and also provides an illusion that the air is cooler by constantly ...


5

Rather than go full mobile-home park and start boarding (or foiling) up the windows, they do make window film specifically for this: Gila Heat Block Film (just one example) That film might be enough to fix the problem, and if you install it carefully, management will probably not care if you leave it in place when you move. If that alone doesn't block ...


4

You also want to ventilate the attic space. If there is a space between the ceiling and the roof, its going to get pretty hot in there. In our house it can get above 190 °F. You can get gable mounted fans that suck in air from outside (at 100 °F, or what ever temperature it is outside) and force the 190 °F air out of the attic. Another thing ...


4

Solar curtains - beware I haven't seen any that look much better than aluminum foil.


4

To the extent that it matters at all (and it shouldn't, because there are fire-resistant walls between the garage and any living spaces), the extra load on the air conditioning is proportional to the temperature of the garage and nothing else. The heat flow from the garage into the house is proportional to the temperature difference between the two spaces, ...


4

You're looking for the V in HVAC (Ventilation). There are indeed systems that will pull in outdoor air, filter it, and supply it through the home. These systems would likely be in addition to any heating or cooling equipment, not as a part of them. To be specific, you're looking for a balanced ventilation system. Talk to your local HVAC company, they ...


Only top voted, non community-wiki answers of a minimum length are eligible