Preparing The Evaporative Cooler Duct For Winter

I’m still not done renovating the interface from the evaporative cooler to the underground duct work. I’m getting close but I need to get it sealed up for winter before I finish it this year.

The typical set up for cooling and heating in New Mexico involves separate evaporative cooling units from heating units. Dampers are installed that block air from entering one unit when the other is running. The damper is almost always a flimsy piece of metal that slides into the duct without any kind of insulation or air barrier around it.


This is fine when blocking the cooler air from entering the heater in the summer but it’s not fine when blocking the heated air from entering the cooler in the winter. I’ve been looking at automatic barometric dampers, they open and close based on which way the air is moving. Some automatic dampers look like they might seal the air penetrations when closed but they are not insulated. I’m thinking of designing my own insulated automatic barometric dampener but for now I’m going to have to seal the duct manually.


I started by cutting a piece of polyethylene foam I had from some shipping materials slight larger than the 18 x 18 inch opening. I placed it over the flimsy metal dampener. I sealed it up with some self adhesive foil covered foam pipe wrap.


I covered the lower portion of the duct that is under the dampener with more polyethylene foam and covered it with the foil pipe wrap.


It should be well sealed and airtight for this winter and easy to remove the foam when I finish it up next summer. I still have a number of issues to deal with.

I had Steamatic come out and clean the duct work. They tried cleaning the main duct from the cooler to the manifold the distributes the air to the rest of the house. The dirt was too caked on to get it all. The Steamatic guys suggested I pull a flexible duct through to seal it up.

It’s a great idea and something I will try next year. I also need to finish sealing the main interface with cement and sealing it with a moisture barrier.

It’s still hard to believe that the previous residence of my house was a HVAC contractor considering all the problems I have had with the evaporative cooler. I haven’t started writing about the super crappy heating system.


Attaching The Evaporative Cooler Duct Work To The Concrete Pad

Last year I received a Master Cool evaporative cooler for free. I purchased some duct work from a local home improvement store but never permanently attached it. I had used duct tape to hold the whole mess together last year. Duct tape does a poor job of sticking to concrete.

This year I came up with a method of attaching the duct work by installing concrete bolts and bolting down extruded aluminum L channel to the concrete. I considered gluing the aluminum directly to the concrete but I wanted to have the option to remove it in the future.

Broken concrete drill bit

I learned a few things about drilling through concrete. First: it takes a lot of power and my cordless Dewalt drill had a tough time with the drilling. It was just really slow (perhaps a lithium ion nano battery would have helped). I was meaning to buy a corded hammer drill anyway and the corded drill was 10 times faster. Second: it was easier to drill the holes in the aluminum L channel then use that as a template for drilling the concrete, rather than marking the concrete. The drill bit tended to walk a little in the concrete. Third: drilling concrete is hard on the drill bits. It’s good to have extra on hand.


I attached double sided window and door weather stripping to the aluminum L channel but left the paper backing on the other side. I filled in any remaining gaps with some outdoor rated silicon sealant.


I am far from done with this project. I need to verify that water is not leaking into the duct. I need to have someone clean all the duct work so I have not completely sealed the duct to the aluminum L channel. I want to install some sort of concrete sealant to the duct once it’s cleaned out.

Finally, I want to build a better stand for the cooler. I envision a wheeled stand with a built-in jack so I can easily move the cooler around for maintenance and adjust its height without additional help.

Making A Small Repair With Hydraulic Cement

This last summer I had issues with my under ground duct work leaking water from where the evaporative cooler connects to the cement duct work. The fix involved fixing a large amount of cement in a vertical application. It’s easy to miss something when patching cement on the inside of a 18 inch hole. I’m not sure if the picture I posted to Flickr shows it very well but I missed one little void, a slot just big enough for a quarter to fit through.

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IMG_1104To my great frustration this small slot was enough to flood the underground duct work with water during a rain storms. Once I indentified the problem I had to figure out a way to fill that hole back up with cement.

Regular cement shrinks when it dries. I used hydraulic cement which expands as it dries. To apply it to the hole I mixed a very small amount of it in a ziplock bag with water. I then cut the tip off the bag and and squeezed it into the hole like cake frosting.

It worked great and so far there hasn’t been any more leaking. The real test will come during the summer monsoon season.

Vertical Cement Application

Cleaning up the swamp cooler duct work continues. At this rate I might have it done by summer.

This is my first experience mixing and using cement and I’m pretty happy with the result. Here’s the problem, a large swath of concrete is missing and the original metal duct just rested up against dirt, further degrading the metal. I cleaned up the mess and prepared it to be filled with cement.

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First thing I did was to put some metal lath that is used for stuccoing walls. I folded it in on itself and shoved it into the gap using a few nails (nailed into dirt) to hold it back where it needed help. The metal lath not only will give the cement some strength but will give it something to stick to.

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I used 30 lbs of Quikrete quick setting cement. The cement sets in 10-15 minutes and, according to the container, is recommend for vertical applications. Since I had never mixed cement before it seems like a good first step was to read and follow the instructions. The container says to mix 5.5 parts of Quikrete into 1 part water and only mix as much as you can work with in 10 -15 minutes. Mixing that much water resulted in a wet powered that was pretty much useless. After some experimentation and wasting about 10% of the Quikrete I found I needed about 3x water than was called for.

Another 10% waste of Quikrete occurred trying to figure out how to actually apply the material into the hole. I finally figured out that using a wide putty knife and pushing it up, working my way left to right and top to bottom was the easiest way to apply it. Sometimes it would fall after I put in on and I tried to scoop up as much as I could and put it back.

It was hot and sweat and blood literally went into the making of this. There is a satisfaction to doing it myself..

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There’s a few next steps before I can permanently attach the duct work. The floor of the this concrete pit should also be solid concrete, but is degraded and it’s hard to tell where the concrete ends and the dirt starts. I will have to put about a .5 inch layer of cement down. I will probably use something like the Quikcrete Fast-Setting Self-Leveling product. Since it doesn’t require any trawling, it should be easy!

The other thing I have to do is to clean out the dirt that made it’s way down the main duct that runs from the cooler to the main air distribution point. I could hire a duct cleaning service, but why start hiring people now when I’ve done everything else myself?

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Emergency Cooling

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It’s been hot here. Unusually hot. This last week has been in the mid to high 90’s which seems about 10 degrees more than usual. This poses a problem for me. Last fall I removed the swamp cooler due to the duct work rusting out and making a mess and I haven’t yet resolved it. I realize it’s June and I should be prepared for the heat already, but I wasn’t expecting this much heat at once.

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I managed to get the old rusted duct work removed but I’m not yet done getting the cement casing cleaned up. I did get a MasterCool for free but needed to get it blowing cold air into the house. Getting this small amount of duct work made was going to be extremely expensive, one company quoted me $600 – $800.

The Lowes and Home Depot don’t carry duct work larger than 8”. Luckily I was able to find a local hardware store called Samons that carries pre-made duct work. Not being ready to permanently install the duct work… let me just say that if your a fan of duck tape, you will be a fan of my work.

I have a managed to duct tape the whole mess together and sit it on the cement hole. If there’s a strong wind it will probably blow the duct work away, If it rains It will probably fill the hole with water. For now I’m cool.

The Poorly Desgined Forced Air Heating Unit

Equipment Closet

The former owner of this house was a HVAC contractor who appeared to own their own business. I’m pretty sure about this because I have found their business related items around the house. Since the house was foreclosed on, i assume they went out of business. I have no idea if they installed the forced air heating unit in this house, but if they did I can see why they went out of business.

To start, the heater is a Frasier-Johnson brand, which doesn’t appear to be made anymore and when it was, it was a low end brand. This heater has a EnergyGuide rating of 80, and the lowest scale is 78. Pretty much the least efficient you can get. The main problem is with the filter configuration. Two filters sit in a “V” configuration above the heating unit, but there is no easy way to install the filters.

There is no access panel in the duct work to put them in. The only way I can figure to put the filters in is to push them up from inside the heating unit. I have to reach about 12 inches inside the heater, reach around motors, electronics and whatever where I’m left with about an inch of space to get the filters inside. From there they have to balance precariously on a few pieces of metal in the “V” configuration, where I can’t actually see how they are setting without getting down on my knees with a flashlight to look up inside the duct work. They aren’t sealed against the duct work and one of them keeps falling out of place leaving huge gaps.

I’m looking at possible ways to cut up the duct work above the heater so I can access the filter area. Doesn’t look easy though.

The Mess That Is My Underground Duct Work

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This was only the second summer I’ve lived in this house, and the second year I’ve ran the swamp cooler. I thought I was lucky to have a swamp cooler that sets on the ground instead of the roof. I expect to have some dirt get through the ducting, but i had quite a bit of it all summer long this year. I also found that the cooled air was making it out our under the concrete pad that the cooler is setting on. Summer is over, so i pulled off the swamp cooler to take a look. I found a huge mess.

The metal duct work is mostly rusted away. I would expect that the ducting would be incased in concrete, which it appears there was an attempt to do so. Except only 50% of the ducting had concrete surrounding it, the rest was up against dirt. Damp dirt, which led to the rusting and the mud which penetrated the ducting.

I pulled up the majority of rusted mess out. I allowed the pit to dry out then vacuumed up as much of the dirt with a shop vac as I could. I also found a layer of dirt in the 18 inch duct that leads to the main distribution center under the forced air heater. Thankfully that where the dirt stops.

Temporary sealing of duct work for winter

I’ve got a huge mess to clean up. I’m going to need to talk to a HVAC contractor to see what can be done. Hopefully I can do most of it myself, but I will need some advice. I decided not to deal with it this fall, instead I sealed up the main 18 duct so the heated air wont get out this summer. I took a piece of foam and a piece of plywood, sized up to the wall where the inlet to the house is, and held them with some 2×4’s that I hammered into place.The foam compresses and seems to have a good seal. I filled any other holes with pieces of foam and some expanding foam.

If your interested in following the progress, you can view pictures at a flickr set.