Today's Power Trip - Heating Duct Insulation and Raccoon Paradise

by Don Ames,

Please read the article and catch the screen cast at the end of the article.

Earlier in the week, I spoke about construction flaws and how builders have a tendency to build energy waste right into the structure of a home. The contractors really don't mean too, we all understand that, but , never-the-less, poor construction design, short cut methods, and lack of worker diligence can provide ready made, built-in energy flaws. You have a nice house that you are proud of, but it could have energy-loss disease and the only place the disease shows itself is on your monthly power bill.

Before I get into sharing Today's Power Trip, I want to mention a few headlines that caught my eye.

How about the headline that read something like, "Matt Damon put's his money where clean water is needed." Of course, Damon is the actor that is concerned about the billion people without enough clean water. Here in the rain forest of America, it is hard to imagine spending 80% of your day looking for and collecting water. I just hope all those people in those other places solve their water problem before the situation spreads to my backyard. Is this an energy conservation problem? Is this something we really need to be concerned with when we live so far away?

Another story that grabbed my attention has to do with changing the oil in your car. I guess some organization in California is suggesting that cars do not need to have the oil changed every three thousand miles. The owners manual in my car recommends an oil change frequency of 3,000 miles. I guess new ( or real ) evidence suggests cars can go 5,000 to 15,000 miles safely between oil changes. Considering all the cars in California, changing the oil replacement frequency from 3,000 miles to 6,000 miles would save a boat load of oil. I know this about energy conservation, but I wonder how concerned people are and whether or not they will make changes for the good of energy efficiency.

I know two things for sure, I have been changing the oil in my little Ford every 6,000 miles for years and it's humming along like it was new. I also know, when I was driving 18 wheelers, I changed the oil in the Cummins every other week or every 10,000 miles, which ever came first.

Lacking Support

Heating Duct Insulation and Raccoon Paradise

Yesterday, I had the good fortune to go into the underfloor space on a double wide manufactured home. The homeowner contacted me and indicated the home was not heating well on one side. I asked him if the side of the home that was not heating well was the side of the home that did not have the furnace room. He confirmed that was the case.

A double wide manufactured home has the furnace installed on one side and a cross over duct that carries the air over to the other side. When one side of a double wide is heating well and the other side is not, it is almost always a problem with the cross over duct.

With the help of a pair of coveralls, a paper mask, flashlight, and a camera, I head under the home. I spot the crossover duct and head in the general direction, altering my course to wiggle under a 3 inch drain pipe. I don't go very far before my nose brings the answer to the heating problem. The smell of Raccoon is noticeable and identifiable. I suspect when I reach the cross over duct, I am going to find the large flex duct with a large hole in it from the teeth and claws of a homemaking Raccoon.

I spot an area off in the corner of the crawl space that sports a number of little land mines. I have been on the look out and I am relieved to see the feces confined to an area not in my crawl path.

Reaching the cross over duct, I find it is in one piece, but the supports have come loose and the duct is laying on the ground. The duct has been crushed in two different locations. I guess a Raccoon is heavier than I thought. It is apparent that the vermin have been making a bed of the heating duct and the duct is collapsed in two areas.

While I am looking at the damage, the furnace comes on and starts trying to blow air through the duct. It is interesting to watch, because the outer plastic layer billows up with air pressure, but the inner insulation layer remains collapsed and air is restricted from passing through.

Damaged by Raccoons

In order to get heat back to the far side of the home, two things need to happen:

1.  The cross over duct needs to be replaced.

2.  The perimeter of the foundation needs to be secured so the Raccoon can no longer use this underfloor area as a bedroom.

Which is better, flex duct or solid metal duct.

Usually, a solid metal duct is the better performer. In the case of vermin, the solid duct will be able to withstand the attach better than a flex duct. The solid metal duct that is wrapped with insulation, in the face of a family of Raccoon's, will have the insulation torn off, but a better chance of maintaining the passage of air.

In this case, a Heating Contractor has provided a proposal to replace the crossover duct with a 12 inch solid metal duct. The bid price was $738 dollars. Seems a little high to me.

I believe the homeowner, who is on a fixed income, will choose to have his nephew replace the duct with another flex duct. The cost of the duct and a couple zip ties should be about $80 dollars.

Three things that are really hard on Heating Duct Efficiency:

1.  Moisture.

Moisture is hard on both metal ducts and flex ducts. I have seen metal ducts that are rusted through and I have seen flex ducts with the interior insulation soaked and collapsed.

The moisture can get into the ducts from the toilet that overflowed, the kid scooping water out of the tub, a leak in the roof,  a plumbing leak in a wall, or from a leaking water heater in the bedroom closet.

Insulation Damaged by Coons

2.  Vermin.

Heating ducts are warm and there are few places your outdoor cat, or the neighborhood raccoon, would rather sleep than on a nice warm duct. They like warm ducts so much, that they are not bashful about rearranging the duct insulation to their liking.

3.  Lack of proper support.

A heating  duct is at it's best when it is tight and straight. Improper support can leave a duct pinched off, bent, sagging, or disconnected.

4.  The Ground.

Heating ducts that touch the ground are apt to be compromised by the three items above. Ducts that touch the ground, whether they are metal or flex, will draw moisture, vermin, and invite deterioration.

The Security of Energy Conservation.

Whether you have a family of domesticated Raccoon in your crawl space, or you have to walk 2 miles to get a cup of dirty water, the world is getting smaller and the need for energy conservation is getting greater. When one person in urban New York decides to make a change and increase mileage between engine oil changes, it has a small effect on the future of a teenage girl that lives in a grass hut on the side of the Kalahari. Energy conservation is about heating ducts, oil changes, clean water and security.

If the screen cast does not play for you, try this link.

Thank you for stopping by Detect Energy, hope to see you soon, but I won't leave the light on for you...

More from Don Ames and Detect Energy at

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Tags: crawlspace, duct, ducts, heating, insulation, raccoons, underfloor, vermin, weatherization


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Comment by Don Ames on January 23, 2012 at 2:35pm

Hal, thanks for following up with all the additional information from the experiences you have had. There is no doubt that vermin under a home costs the household through damaged insulation and then increasing heating and cooling bills. I am going to look at the Cerama-tech product that you mentioned. Have not heard of it before and will take the opportunity to learn more.  Thanks again,  Don Ames

Comment by Hal Skinner on January 23, 2012 at 2:08pm

The metal duct was actually 3" x 12" x 30'.  My apologies on the misquote.



Comment by Hal Skinner on January 22, 2012 at 3:27pm

Hi Don.


Have not had to deal with Raccoons yet, as far as I know.  However, we did solve a problem with field mice and rats tearing up the R-11 fibergalss insulation under a single wide out in the boonies.


The insulation was under the entire mobile home up against the floor and the 6" x 12" heat duct that ran the 34 foot length of the trailer.  The fiberglass had been torn up and carried off by the rodents for nesting material.  It was described to me as "Pretty much gone" by the painters doing the job for the Park District.


They did a before test with the fiberglass still in place.  Then they removed the remaining fiberglass and painted the underside of the trailer and the heat duct with our coating.


Comparing the before and after results, this resulted in an 84% reduction in heater run time to bring the trailer up to 72-degrees.


The trailer has a pretty tight and secure metal skirting so I doubt if raccoons could get in but mice and rats apperently could.


I will try and attach the park districts statement and report.



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