random walk through fields of musings

Wednesday, March 10, 2010

seeing things in a different light

Not being able to justify purchasing an IR ("Thermal imaging") camera and not finding one nearby for as good a price, I rented a FLIR b50 from flir.com for $425 per week ($25 sales tax plus I pay overnight shipping both ways) for the past week. The main purpose of the rental was to take followup pictures of our community's common house to see if the added insulation in the attic really made a difference but comparing the before and after IR pictures was complicated by the fact that the before pictures, taken by an "Energy Audit" firm, didn't have the temperature to color legend embedded.

In any case, I took pictures in my own unit, and the results mostly confirmed what I already knew.
  IR 0124 lens cap
don't take pictures with the lens cap on!

IR 0125 skylight
the skylight leaks heat like crazy -- 15 degree F difference between inside and skylight is more than the 10 degrees F a regular window typically has:

IR 0128 front door
blinds and most types of shades really do work well to keep the heat from leaking out windows -- here's the gap between shade and window and another one looking at an upstairs window which also has a thin curtain in front:
IR 0194 leakage around a honeycomb blind IR 0200 MBR upstairs window with shade
one of our upstairs windows was broken by a small rock a few years ago and replaced, however the replacement definitely isn't as well sealed as the original:
IR 0833 MBR S windows no drapes, right is Diamond glass replacement IR 0834 MBR S windows, right is Diamond glass replacement
(hint: replacement is on the right in both pictures -- I took two just to show that reflection works in all spectra) - that shoddy replacement is almost 10 degress F worse it seems...

Finally, our upstairs Master bedroom is always colder in winter than either the downstairs (where the thermostat is) or even the other bedrooms on the same floor. Originally we thought it was a lack of insulation in the attic above the master bedroom (which wouldn't account for it retaining heat well when heated by sunlight, but anything else seemed remote and unlikely), so we added insulation to the attic to no avail. An HVAC person confirmed that the room seemed pretty tight, but noted that the two ducts leading to that room were each less than half the size of the ducts to any other part of the house and so he posited that sufficient warm air, especially on the long run to that room, was just not making it to that room. To fix that, he'd have to replace the ducts which would have involved tearing open the walls etc., so might just be cheaper to put in booster vents in that room. With the IR camera I have proof that he was right:
 IR 0195 vent while furnace is on IR 0196 cold air return
that's a downstairs vent while the furnace is running -- around 114 degress F coming out (even if the numbers are uncalibrated, we hope that in relative terms they are pretty accurate) and a vent in the bathroom on the same floor, at an oblique angle and farther from the furnace. Next, we look upstairs:

IR 0201 guest room vent (compare with MBR vents)
in the guest room upstairs, it's about 104 degress, pretty good and that bedroom gets sufficiently warn by our experience. Now the kicker:

IR 0198 upstairs bedroom E vent (about 8 degress cooler than downstairs vent) IR 0199 upstairs MBR SE vent (12 degress cooler than downstairs vent)
Those are the two vents in the master bedroom, anywhere from 8 to 12 degrees cooler than the vent in the guest room. Clearly, not enough warm air is making it up into that room, and part of what does make it into that larger room probably escapes into the landing and up via the skylight due to a chimmney effect.

All these photos were taken at night to minimize sun glare/reflection effects.