AC Temp setting

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The difference in settings based on indoor and outdoor temperatures.

In my part of the USA the humidity in summer makes life miserable; the heat is not so bad. When the A/C runs more it dehumidifes more. So on a very hot day when it is straining to do its job, running frequently if not constantly,80*F inside (when it is 90*F ouside) is comfortable because the humidity will be low.

When it is 80*F oustide the A/C doesn't need to run at that setting, the humidity will make it uncomfortable. So lowering the setting to say 75*F or less will help that.

In my house, heat was not generally needed until it reached 40*F or below outside. But as it got colder out (teens and 20's) the walls would get cold (probably poorly insulated) and one does not feel as comfortable as one's body heat radiates towards cold surfaces; windows, walls, ceilings etc. This necessitates turning UP the het. The opposite is true with radiant heating. One feels warmer at cooler room (ambient air) temperatures when surfaces are warm /giving off heat.

Excessive or not enough heating and/or cooling, I'd say, is a stress to one's bodily system and one catches colds, etc. The closer the indoor and the outdoor temps are to each-other (within reason) the less one's body stresses, IMHO


[this post was last edited: 6/7/2010-14:02]
 
Mayguy - nice video. I have an XV80 with Comfort R. I could not get an XV90 because I cannot direct vent due to code. Comfort R makes a big difference in the indoor humidity.

I noticed your air cleaner which is the same brand as mine but mine is electronic and not HEPA. It looks like the HEPA filter would fit into the space my current cells occupy. Did you replace the electronic cells with the HEPA or is it orginal?
 
temps

central air 3 1/2 ton on a programable thermostat - 70 on the weekends, goes up to 80 or 85 during the day when not at home and back to 70, been putting it down to 68 or 69 when i'm there.
The a/c was keeping the house at 71 yesterday, it was about 97 outside, turned on the little a/c in the kitchen and the one in the bedroom to help get it a little cooler. Keep the bedroom at 60 at night, nice and snuggly. :-)
If during the 100 degree days it can't get it back down to around 70 then will put it on hold. I like my cool air!
 
When I lived on the mainland, I'd keep my ac on 72 during the day and 78 at night. Here, I have yet to even need ac and freeze to death when I go places like the grocery store or a movie theatre.Some nights, I have to wear a jacket or sweater to stay warm. Especially when the tradewinds are blowing.I have all screaned sliding windows and both of my enterance doors swing in or out.The ceiling fan keeps a good flow of air going and my air purifyer does a good job keepin the dust to a minimum.
 
I have a programmable thermostat. In summer it keeps the house at 78 during the day, turns down a degree to 77 for evening comfort as we are fixing dinner running around etc. Then at 11:00 it turns up to 80 for the night.

I also keep the upstairs closed off with the stairway door shut as to not heat/cool the unusued portions of the house. There is a window unit in the bonus room upstairs rather than switching the ductwork if someone is visiting and uses that room.

Hijack,
I also hung clothes out this weekend to take advantage of the solar dryer. My Mother couldn't understand why I had a brand new dryer downstairs and I was hanging out the sheets.
"Because" I told her "I can run the A/C for about three hours for what it would have cost to dryed all the bedding. Since our dearly beloved Westar just got ANOTHER increase our rates will almost double if we use more than 900 KW per month June through September.
 
Cool in Las Vegas

This was hauled up to the roof last Summer. The prior 25 year old Carrier finally bit the dust. So new 5 ton unit with gas furnace. We're keeping it at 74, current temp is about 104.

While I'm working on my accounting homework, am listening to a neighbor's A/C unit condensor fan screeching. Sounds like somebody will have an repair bill coming soon[this post was last edited: 6/7/2010-17:09]

ironrite++6-7-2010-16-23-20.jpg
 
Question

Regarding closing ducts and closing doors as to not heat or cool the unused portions of the house.........It seems like I remember reading somewhere not to close any ducts on an HVAC system. I used to keep 2 ducts closed off but I opened them back after I read that.
 
It seems like I remember reading somewhere not to close any

As far as the heater goes, closing any vents can possibly overheat and crack the manifold. I forget the reason related to A/C, but it's just as important for A/C as it's for the heater to keep all of the vents opened.
 
I keep mine at 73 24/7. I have tried setting it up a few degrees but it gets too humid. I have NEVER like the heat, and now that I am turning into an old fatboy, I like it less... lol!
 
Jerrod

My air cleaner is a F200 Media air filter, not HEPA. It can be upgraded to an EAC (electronic air cleaner) if I wanted to.. But I like the Media better than EAC since it does a better job, and only change the media twice a year.

Code issue on PVC? That's the first.

Do you have a humidistat and two stage stat on your system?
 
Roof mounted AC unit

when I was a boy and we lived at Holloman AFB-near Alberkerki(not sure of spelling)we had a roof mounted "desert coooler" on our house-in the spring Dad would climp up on the roof with a hose and fill it with water-in the fall he would have to climb back up on the roof to drain it so the unit wouldn't freeze during the winter-that made a good substiture for an AC.
For AC units-you should keep ALL register vents open-you want max airflow thru the system-best efficiency that way and to keep the evaporator from possibly icing up.Poor airflow from blocked or closed vents could make your evaporator coil ice up.Otherwise I haven't seen too many rooftop mounted home HVAC systems-mostly see that on commercial buildings-and the building I am in now-the chiller condensor units are mounted on the roof behind a barrier so you don't see them.Someone put the barrier up-who cares-not many will see the units.This building is out in the NC countryside!No houses or other buildings for a few miles!Just nice farmland and Weyerhauser property-with trees.
 
Guys im not sure what you mean when you turn up the heat to compensate for when it gets really cold out.

If the walls are not well insulated then the house will lose heat quicker and this will mean the heating system will come on for longer to heat the house to say 22C. Bumping it up further to say 24C just means the unit still has to heat to 22C before it can get to 24C.

The warmer you have a house the quicker the rate at which heat is lost from the home.

If the walls are losing heat then the system will compensate by staying on for longer.

I live in a very old victorian house that loses heat fast, the walls can get very cold in winter but my thermostat is still set at 22/23C which is a comfortable temperature. We dont have to increase it any higher.
 
My understanding from working in this line of business is that if you have a ducted or central a/c then you will save money by closing up vents as the unit isnt havng to work as hard.

Perhaps on older systems this may cause poor airflow issues meaning frozen evaporators but on modern systems the units sense if the coil is getting too cold and back off.

Whats the point heating/cooling rooms your not using.
 
Roof Mount

Tom, this area was built around 1978. Roof mount units were the what most houses have. The whole system, A/C, heater, etc is in that one unit. No air exchanger in the house. New homes out here do have a split system with the compressor mounted on ground level.

With the roof unit, it is harder to retrofit a "swamp" cooler like. Those use water, either recycled or running over pads and work very well with our usual low humidity.
 
"Code issue on PVC? That's the first."

I decided to try the unit without the humidistat to see how that worked and it is fine with just using the variable speed blower and the Trane Comfort-R routine. I have a Honeywell VisionPro multi stage thermostat.

I live in a downtown residental neighborhood so we have sidewalks in the front. No gardens but by zoning code every house must have a garden space in the back. My utilities are in the front of the house and the venting code will not permit the venting of hot gases over a sidewalk. I also live an a neigborhood that has been designated historic and am also under those additional zoning restrictions....long story there.

Contractors know that we cannot vent due to code and so far they have refused to install that kind of equipment - heater or hot water heater.
 
"Code issue on PVC? That's the first."

Ok, now I understand. With the 90% system, you may have ice/water to worry about in the sidewalk if the vent is venting out there.
 
Closing Vents

There is a HVAC talk forum on the web and the Pros there don't recomend closing vents and returns. They say that for heaters it could cause excessive heat to build up in the exchanger as well as cause premature blower failure because of increased static pressure. They have found many problems in new construction because short cuts have been taken and supply and return ducts are often not large enough. They don't recommend it if you have a variable speed blower because the blower will simply increase its speed to overcome any restriction in air flow causing it to use more electricity.

I used to close off some supply and return vents but after reading this I have everything wide open and guess what? - I get more air flow in every room of the house, and I have only one system heating and cooling a 3 story house, so I am sold on everything - wide open.
 
"Code issue on PVC? That's the first." - BUT

Systems below 90 AFUE are being discontinued because they are not as efficient so I don't know what I will do when I need a new heater. I guess I will switch to a heat-pump
 

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