What is heat loss through solar tube?

Old 02-01-17, 01:44 PM
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What is heat loss through solar tube?

I live in a fairly mild climate in Northern California, yet during the winter my house is cold and the central heat seems to cycle on far too often and run too long. I'm trying to identify what the major culprits are as far as heat loss.

I have a 22 inch flexible solar tube in the living room. It is about 12 years old. It does not appear to have a double pane lens but I cannot tell for sure. The run for the flexible duct from ceiling to roof is about 5 feet. I'm wondering what the general opinion is on whether solar tubes cause significant heat loss; that is, heat going through the lens and passing through the tube and out through the roof? Any ideas on how I can check the "efficiency" of the solar tube I have? Thanks.
Old 02-01-17, 02:40 PM
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Every solar tube skylight I have viewed with my thermal camera has been terrible for heat loss. At best yours is probably about what a thermal pane window would be. They are also bad in summer by letting in a lot of attic heat as most tubes are not insulated so you have the full attic hot temperature against the uninsulated lens in your ceiling.
Old 02-01-17, 03:04 PM
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I can't see the tube as having that much loss to be so noticeable.

How old is the house and how is the insulation ?
Old 02-01-17, 06:00 PM
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I agree with Pj, it would be about the same as a poor window. In summer, as PD said a bit worse because it passes through a very hot attic. But in winter no different than looking outside.

Insulation and air leakage are the two primary sources of heat loss. Air leakage is perhaps the least expected as homes will lose a lot of air. A typical estimate is all of the air inside a home will leak out and be replaced every 3 hours. Some homes a quickly as 2 hours.

There are a few major contributors to the leakage, a fireplace, space around a chimney, or holes for plumbing and electrical. Occasionally a dropped ceiling will provide an easy path for air to escape.


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