Author Topic: Silly Question, but Im going to ask it anyway.  (Read 1602 times)

Offline geno555

  • Sr Member
  • ***
  • Posts: 546
Silly Question, but Im going to ask it anyway.
« on: October 09, 2009, 05:00:07 PM »
Having a bit of a dilemma about the electric ceiling fans in the new house, there still in the boxes, but I am either really confused about what I remember or little (maybe that\'s the problem) I remember about air circulation.  ;D

Isn\'t it true that cool air settles to the floor while warm air rises toward the ceilings?

If so and all the fans are reversible, meaning simply they can push air toward the floor or pull air toward the ceiling.

Right now and I don\'t know how this is possible but the top floor, the second story which is true does not have a roof on it baking in the sun, but the difference in both air flow and the difference in air temperatures between the two levels in the middle of each level, meaning one reading is not having the advantage of sitting on a window sill but is place on 3 foot wooden table in the middle of a room.

The air upstairs at 2pm, the hottest part of the day averages for the past 5 days, no rain, so I can use that as a factor, but the average difference in temperatures between the upstairs is 8 degrees cooler than downstairs.

Not going into detail but etc. day one  day at 2pm upstairs it was 96 degrees F

Downstairs’ it was 103 degrees F.

First thing you are going to say damn that’s just too hot. Well guys and gals using the same thermometer, it was 105 in my Nanyays livening room and they were all sitting there just watching wow wow  wee!  ???

So my question is if that stays like that after the roof and insulation is laid and its cooler upstairs than down what should I do, if I turn the fans on upstairs to suck the cooler air from the floor toward the probably by then hot ceiling, or do it turn them on the other way and try to push cool air downstairs, and the same for the fans downstairs, do I push the hot air toward the cooler tile floor or suck it up toward the already hot ceiling?


My father god bless his soul at 86 says to me this morning on the phone “Boy I have been heating and cooling this house before Hitler was a road guard! All my fans are on reverse and suck up air from the floor. He lives in a ranch style house 4 bedrooms, and then I said but Dad, remember I was your power of attorney when you had the heart attack I paid your bills,, he adds quickly but now I am on a plan I pay the same amount every month and at the end of the year either get some back or owe some, I said how much a month he said cheap 750.00. I thought I would lose what little O2 I had left in my body, I said day I can’t afford a 750.00 dollar a month electric bill.  :o

So does it make one bit of difference which way the fans are turning. There are 7, four upstairs and 3 downstairs.

Boy I hope not for it does, I am hooking these bad boys up to a remote control device of some kind that the computer will turn off and on according to temperatures and air flow?

The Murf
 ;D

Offline c_a_p_t_a_i_n_r_o_n

  • Sr Member
  • ***
  • Posts: 1,794
Re: Silly Question, but Im going to ask it anyway.
« Reply #1 on: October 09, 2009, 07:22:04 PM »
HOT air rises, cooler air sinks....fact of nature

Ceiling fans for US/European market ARE GENERALLY meant to be reversible
To force air downward in winter to keep occupants warmer, upwards in summer

Although I seem to recall (nearly 20 years since I bought them) that SOME fans are NOT reversible

In your case Murf I suspect that the air downstairs doesn\'t circulate as much as that of upstairs and that is causing the warmer temps downstairs

Push the air up from the downstairs rooms, vent into upstairs and push up again upstairs


  • Guest
Re: Silly Question, but Im going to ask it anyway.
« Reply #2 on: October 09, 2009, 08:21:27 PM »
We have one non reversible ceiling fan in out lounge and it blows down from a hot uninsulated bungalow ceiling. This causes hot air to be blown down on us and circulates the cooler lower air across the hot ceiling. It does not make much sense to me, so we only use it during the cooler parts of the day. We use floor fans at other times and leave the hot air at the top of the room. Ceilings are made higher in hot countries to keep the hot air above head height, so why blow it back down again. Even if the fans blow upwards, the displaced hot air is going to come down elsewhere in the room. I will not be fitting any inside my new house, but possibly a couple in the covered and open patio area.

Colin

Offline coutts00

  • Sr Member
  • ***
  • Posts: 1,470
Re: Silly Question, but Im going to ask it anyway.
« Reply #3 on: October 10, 2009, 08:50:03 AM »
It would be good to get Maricel or another Architect to chime in here but as I have a lot to do with Aircon principle in IT work, here goes.

Stairwells should have doors, this stops hot air from going up stairs and cold air from going downstairs.

Ceilings should be hollow between floors, this allows return air from an aircon or an exhaust fan to pull out the hot air and not recirc it back to the aircon, making it work harder, yet at the same time a thermostat with an internal and external sensor should be put in to pull cooler outer air into a hotter internal temp room without the aircon cooling it first. Cheaper on the bills that way. A thermostat should be put on the exhaust fan in the roof duct so when the cooler air from the aircon reaches it, it shuts off and allows the aircon to recirc the cooler air, lowering the work load.

Trees should be placed around the property to increase shade on exterior walls as much as possible, reduce the external temp of the walls and reduce the interior temperature. Heat flows to the lowest point, if the outside walls are cooler than the interior space, the heat is sucked out the walls to equalise the temp, and vice versa. If the interior is cool and the outside is hot, the heat will flow through to the colest point.

So have as much insulation on internal walls as you can justify, as much insulation in interior ceilings as you can justify and doors on all stairwells. Fans move air, air evaporates sweat and we feel cooler. Those of you from the cooler climes will already know to keep doors and windows closed and sealed to prevent cold outside from getting inside, same for hot climes but the reverse, if your room has aircon, keep it locked up tight, check for leaks, find an infrared thermometer or laser thermometer, check wall and windows for leaks, caulk and seal.

Wayne   ;D ;D
Wayne  ;D ;D

  • Guest
Re: Silly Question, but Im going to ask it anyway.
« Reply #4 on: October 10, 2009, 12:41:04 PM »
Wayne, I was in the business also many year back.

Your comments are right on!!

The problem I\'ve seen here in the Philippines, a two story building doesn\'t have a dead air space between floors allowing the downstairs hot air to the outside by some means. 2nd floor, 1st floor ceiling are concrete beams and concrete slab.

Now, if a person would put in a drop ceiling, there would be an open area for the hot air to escape if vented to the outside.

As to being cooler upstairs, that\'s normal because there is more air movement. Our 2nd floor apartment is easier to rent for that reason!! In fact, some areas gets more money per month for a 2nd story rental. ;D

Now, being concerned about heat upstairs when the metal roof is added, will depend on the roof pitch giving a lot of room in the attic and how big the vents are at the gable ends in allowing natural air movement.

If that doesn\'t do the trick, an automatic temp. controlled attic fan can be installed at one of the gable vents, at the end that doesn\'t get the most air movement from the outside, allowing natures help the air movement.

You might want to install an electrical outlet for the fan, before the roof is installed, just in case. Cheaper, easier now, then later!  ;D
B-Ray