Evaporative cooler duct work

[Stephen Tashiro]

What's the proper way to arrange ductwork under a downdraft evaporative cooler mounted on a roof? Is it supposed to be sloped in some way or provided with a drain?

A friend has an evatporative cooler mounted on her roof. The downdraft cooler has sometimes pulled water from its pads into the ductwork. This caused the duct below the cooler to rust and the water can leak through it and through the ceiling in a hallway. I think a perfectly adjusted evaporated cooler won't pull water off its pads, but since these coolers are refitted every season and since there are factors like wind, it's unlikely that the cooler will always be in perfect operation.

[Bruce Page]

I have had swamp coolers for 40+ years and never saw one rust out the ducting like that. There must have been a problem with the water flow (too much) or the pan rusted and leaked. Water should NOT get into the duct work, so to answer your question, no, there is no slope to the duct work.

I have serviced my last swamp cooler. I had refrigerated air installed just last week! :D

[Mike Cozad]

Uhh that brings back horrible memories.. I hate heights and I loathed getting on that 2nd story roof to mess with that swamp cooler twice a year (minimum) when we lived in Rio Rancho.

But, to 2nd what Bruce said, no slope and there is some other problem afoot that needs resolved to stop the water intrusion.

[Brian Elfert]

I have serviced my last swamp cooler. I had refrigerated air installed just last week! :D

I'm curious why you went with air conditioning over a swamp cooler? I've heard that swamp coolers are much cheaper to run in dry climates. I live in Minnesota so we have to use air conditioning due to humidity.

[Bruce Page]

I'm curious why you went with air conditioning over a swamp cooler? I've heard that swamp coolers are much cheaper to run in dry climates. I live in Minnesota so we have to use air conditioning due to humidity.

Brian, there are several reasons really.
No water usage.
No allergens pumped into the house.
Better home security – no open windows.
Less high desert dust blowing in because of the open windows.
Better resale value.

Maintenance – It takes an hour or two each spring & fall to set up & shut down a swamp cooler properly. That is time spent on the roof or going up & down a ladder. As I get older that is a maintenance chore I enjoy less & less.

Swampers work best in low humidity. Our hot months are also our monsoon months, particularly July & August. With high humidity our large MasterCool struggled to lower the temp much more than 8-10° from the ambient temp.

The jury is still out on cost. The people I know that have switched say there’s not a lot of cost difference between running a 1hp swamper motor 24/7 and an efficient refrigerated unit.

[Michael Mahan]

I'm curious why you went with air conditioning over a swamp cooler? I've heard that swamp coolers are much cheaper to run in dry climates. I live in Minnesota so we have to use air conditioning due to humidity.
when you live in the West ,water use is a big concern ,
BUT really , think the problem is below
I use a swamp color for my greenhouse the blower should never be blowing water
one of the pads is defective &/or the gullet/gutter on top of the pad hold down array is leaking a stream of water past the inside of the pad
IE : there's s stream of water completely missing the pads or the tube array that delivers the 4 side pads with water ( a 4 way splitter manifold ) has a crack in it & that is peeing water to where the blower is sucking it up .
it's one or the other

mine is a side draft no roofs for me

[Stephen Tashiro]

I agree that evaporative coolers, ideally, ought not to pull water into ducts. However, I've seen them develop many amusing problems. For example, there is tubing in the "spider" at the top of the cooler and I've seen one of the spider's legs blow out and send water streaming down. If a cooler has been adjusted for straw pads, then it's draft may pull water if a person installs synthetic pads. These problems can go unnoticed for a long time. I have a side draft cooler. The duct work near the cooler isn't rusted through, but it's very rusty.

The dust and dirt problem with ordinary (non MasterCool) evaporative coolers is significant. Pads on this type of cooler do not filter out dirt. Unless the house has special vents, you need to leave some windows open and dust comes in that way. Rust that forms in the ducts also gets blown into the house. Hard water adds a white powder to the mess. I added a furnace filter holder downstream tof my cooler. The filters really get filthy compared to filters on the furnace.