Thursday, June 21, 2012

Ceiling Fan Effectiveness

While investigating why my home is not cooling evenly, I ran a quick test.  Using my infrared thermometer, I ran some scans on two rooms.  The test was done at noon, with the air conditioner enabled, set on 85.  The outside temperature as measured by the air conditioner (in the shade) was 89.

In room one (R1) the temperature at the junction of an outside wall, an inside wall, and the ceiling, was 85.9 degrees Fahrenheit.  In the room two (R2) the temperature at the junction of the same outside wall, same inside wall, and same ceiling, was 86.4 degrees.  Needless to say, a temperature variation of half a degree might seem negligible, certainly within an acceptable margin of error, except for one thing:

In R1, the ceiling fan had been running four hours.

This raises an interesting question, if running the ceiling fan for four hours only cools the room by half a degree, is it really working?  Yes, because its not a ceiling fan's job to cool a room: its job is to circulate air.

But wait!  It get's more interesting. 

The temperature of the fan's motor housing was 97 degrees.  This means that the fan was acting as a heat source.  Of course the ceiling fan is equipped with a light kit.  With the light illuminated for one hour, the temperature of the globe around the single incandescent bulb increased from ambient to 95 degrees.  This means the light was also acting as a heat source.  (The four bulb "tulip" light kit in R3 was 103 degrees, using CFL bulbs.  The three bulb halogen fixture in R2 was 118 degrees.)

This experiment causes me to question the value of ceiling fans.  In both R1 and R2 the temperature at the baseboard was 81 degrees.  Conventional wisdom dictates that the fan in R1 would pull cooler air up, or push hotter air down.  By circulating the air, the room would be more evenly cooled.  Yet, the measurements indicate the effect of circulation is not significant.  On top of costing electricity to operate, its possible that the fan is adding heat, not subtracting.

So why do people use ceiling fans if they don't work?  One word: breeze.  People think ceiling fans work, because they can feel a breeze, which seems to have a cooling effect.  (In reality, a breeze is only effective on bare skin because it assists evaporation of perspiration.)

Thus, I will conclude with this philosophical question:  
If a ceiling fan is running in a room,
and there is no one around to feel it,
does it do any good? 

Monday, June 18, 2012

Tear Down The House

To those that suggested that the solution to uneven cooling of my home was to tear the house down... I'm way ahead of you. A couple weekend ago, I took out a ceiling and two walls.

The ceiling had to come out:  There was a leak in the upstairs plumbing that had caused the ceiling to sag in two places.  Once the leaks were fixed, a the ceiling was "repaired" by a couple of "professionals".  And then it sagged again.  So, out it went.

And while you're taking out the ceiling, might as tear down some walls.  The red line represents a wall that separated the everyday dining room from the formal dining room, which has spent the majority of the last five years as a storage room.  The purple line represents the wall that separated the kitchen from the formal dining room.  The yellow circle is around the light switches, that were in the walls, and now just hang down for easy reach.

The big black thing in the background is the Big Fucking Refrigerator (BFR).  The difference between a BFR and a refrigerator is that a BFR damages doors and walls when it goes in the house.  The BFR did sit in the corner where the red and purple walls had been.  Now its against the outside wall.

Sunday, June 17, 2012

Home Not Cooling Evenly

I have a running joke about my house:  I think they installed the insulation backwards, because in the winter, the house is colder then it is outside, and in the summer it is hotter.  Though not completely accurate, I have always been perplexed by the thermal dynamics of this property.

Lets start off with some background.  Like most of the Washington, DC, area (and east coast cities) my home is a "town" house.  Generally speaking, a town house is wider than a "row" house.  A town house is typically two rooms wide, whereas a row house is one room wide.  In both cases, the home would be several stories tall and several rooms deep-- potentially half a city block deep.  (In Tennessee, a house that is one room wide and several rooms deep is called a "shotgun" house, because you could shoot your shotgun in the front door, and blow out the back door.  Sigh...  Tennessee was such a fun place.)

In my case, when you walk in the front door, you can turn right to the living room, walk down a flight of stairs to the master suite, or walk up half a flight to the kitchen, dining room, family room.  So, that's two and a half stories.  From the downstairs master suite, you can go down another level to the computer bunker (ie: basement.)  From the kitchen, you can go up a story to more bedrooms. Thus, we're at four and a half stories.  Turns out there is enough room in the roof, for another 15x17 room, but its never been built out.

The dominate feature of the town house, is the pseudo-spiral staircase.  I call it pseudo-spiral, because its a rectangular box, the size of an elevator shaft, running from bottom to top.  There are three stairs, a set of four stairs at 45 degree angles, then three stairs, and two stairs at 45 degrees.  (If your not good at geometry, you just climbed one story and turned 270 degrees, so you are facing to the left of where you started.)  There is a small landing, and then another sequence of steps.  Repeat this once down and twice up.

I call it the M.C. Escher house:

But here's what you really need to know about the house:  Using my new Harbor Freight Non-contact Laser Thermometer, I have verified that at the lowest climate controlled point of the house, to the highest climate controlled point in the house, there is a thirty degree temperature variation.

Yes, that right: 30 degrees Fahrenheit!  With the thermostat set on 85 degrees, and an outside temperature of 75 degrees, the baseboard of the master suite is 65 degrees.  The largest bedroom upstairs has a 12 foot vaulted ceiling.  At the peak of the ceiling, the temperature is 95 degrees.  And these are ambient temperatures-- the AC is not running!

First questions: Why such a huge temperature variation?  Simple answer:  Heat rises, so the stairwell acts as a ventilation silo that allows all the hot air to rise, and cool air to sink.

Second question:  How do I fix it?

And so we begin...

Harbor Frieght Infrared Thermometer

This weekend, I bought a Harbor Freight Non-contact Laser Thermometer.  I'll explain why in a later post, but I gotta say, I'm impressed with how well this thing performs... especially since it costs $39.99... and I had a 20% off coupon!  :)

First, the laser doesn't "do" anything--  its actually just a pointer to help aim the thing.  Its really a focused infrared measurement device.  The instructions state that it has an accurate range of about 8 feet.  After that, the accuracy begins to drop, but from my minimal experimentation, the loss of accuracy is negligible.  Truthfully, if its accurate within +/- five degrees, it will be worth the price.

The device uses one nine volt battery, which gets depleted fairly quickly. 
Note:  The instructions do not explain how to install the battery.  The front part of the hand grip (black part) slides down.  At the top of the grip, near the trigger, there are four ridges on each side.  Hold the top of the "gun" in your left hand, squeeze the ridges with the thumb and forefinger of your right hand, and slide the grip away from the top of the gun.
 Here's some backyard fun.  With fire!

Flames: 598 degrees Fahrenheit
  Almost ready...
Coals: 946 degrees Fahrenheit
 Sure beats licking the coals to see if they are hot enough.

Welcome Back

David and Paul both complained, separately, that I had not updated my blog in a while. I didn't realize that it had been six months. Time flies when you're having fun... Not!

You see, most of my posts are based on R&D for work related projects, or humorous (read: absurd) events that happen during the day. Recently, much of my day is tied up with logistical silliness. Nobody wants to read a blog post about delivery guys getting mad at me because I wont accept a server rack, because the inventory team won't give me permission to bring it in the building, because my boss didn't get their approval on the rack before he bought it. Boring.

If I wanted to write boring posts that nobody cared about and would not enrich the lives of humanity, I'd post to Facebook.

Having said that, I've started a few personal projects that might be interesting.