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Old 02-21-2010, 06:11 PM  
ZeroAlternate
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Default PVC Pipe on roof

Hi guys,


I have an evaporative cooler on my roof. I want to replace the garden hose that is currently attached to the drain plug with some PVC pipe that would end up draining into a plumbing vent nearby. However, since I live in the desert, I'm no so sure using just any PVC pipe would survive the intense sun exposure and heat we get in the summer.

Does anyone have any ideas of how I could insulate the pipe, or is there a certain type of PVC that is ideal in this situation.

Thanks,

Lowell



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Old 02-21-2010, 06:50 PM  
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Lowell:

If it wuz me, I'd use white PVC pipe.

Seriously, if you have white PVC windows in the houses in your area, then I expect that white PVC pipe would stand up equally well on a roof.

Also, you may have trouble connecting your PVC pipe to a garden hose connection. You'll probably have to use an adapter like this:



or this:



to convert from a garden hose connection to threaded pipe, and then screw a PVC adapter with a female pipe thread onto the pipe thread to get to PVC piping.

Kinda like this:



only with female threads to match the male threads on the garden hose adapter.

(or just use a threaded coupling between the two)



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Old 02-21-2010, 07:18 PM  
ZeroAlternate
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Thanks. The reason I don't want to leave the PVC exposed is that I've done that before, and seen it turn to a brownish black color that breaks easily. but I'll probably end up using some sort of metal pipe. Just to be safe.

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Old 02-21-2010, 08:28 PM  
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Table 2.1.2 of this link
T.C. Forensic: Article 10 - PHYSICAL CONSTANTS FOR INVESTIGATORS
seems to say that PVC is not up to the task.

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Old 02-21-2010, 11:52 PM  
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Lowell:

PVC has good UV resistance. It's not excellent UV resistance, but it stands up well enough that there isn't significant deterioration of the product during it's expected lifespan. Thats why they make windows and siding out of PVC.

Are you SURE that the plastic you saw turn brown and brittle was PVC? I expect it may have been either polyethylene or polypropylene, both of which have poor UV resistance. Or, if it was PVC, it could have been plasticized PVC. PVC can be plasticized so that it remains soft and flexible at low temperatures, like room temperature. Clear vinyl tubing is an example of plasticized PVC. It could be that the heat was baking the plasticizer out of plasticized PVC causing it to discolour and turn brittle. It's the heat that causes the plasticizers in vinyl (aka: PVC) to evaporate out of the plastic, and that's why vinyl dashboards in cars often harden up and crack. So, maybe what you saw was deterioration of plasticized PVC due to heat driving the plasticizers out of it, not deterioration due to the UV light from the Sun.

But, certainly any metal piping would be the most durable choice. Metals are bullet proof when it comes to UV light and normal outdoor temperatures.

The blindingly obvious question, however, is: Why lose the garden hose? It's flexible so that it's extremely easy to drain the water from your evaporative cooler into your vent stack. And, if it's ever damaged, it's easy to replace. It seems that whomever made your evaporative cooler felt that a garden hose would be the most practical way of draining water from it, so why lose the garden hose?

If you're existing hose works fine but is deteriorating due to UV exposure, you should be aware that you can buy garden hoses made of EPDM rubber, which has excellent UV and heat resistance. EPDM rubber is used as a roofing membrane on flat roofs because of it's excellent UV and weathering resistance. It's also the kind of rubber used to make the radiator hoses on your car because it stands up very well to heat. And, it's the most water resistant rubber available. If your hose works fine, but is deteriorating cuz it can't stand up to your heat and sun, you don't need PVC, or even metal... you just need a better rubber hose.

EPDM rubber - Wikipedia, the free encyclopedia

EPDM

Heater Hose - Rubber Product - Elasto Proxy

Where I live, you can buy black EPDM rubber radiator hose in any automotive parts store. If you're fundamentally wanting better heat and UV resistance from the hose you've got now, I'd consider buying some 1/2 inch diameter heater hose at an automotive store and putting garden hose fittings on it. Then you'll have a garden hose made of EPDM rubber that will stand up to more heat and UV light than you can throw at it in a lifetime.

I don't know if radiator hose comes in 1/2 and 5/8 inch sizes like garden hose, but I know that both garden and heater hose come in 1/2 inch diameter, so you can make a garden hose out of 1/2 inch heater hose with 1/2 inch brass garden hose fittings.

You can also buy high quality garden hose and water hose made of EPDM rubber:

Garden/Contractor's Water Hose

http://gardening.about.com/od/toolschool/tp/Garden_Hose.htm

If you opt for EPDM rubber hose, buy it from the places listed under "Rubber" or "Hose & Tubing" in your yellow pages. It'll be much cheaper at those places than at the auto parts retailers. It also occurs to me that for $5 you could take a box cutter and a set of 1/4 inch drive sockets to your local auto wrecker and collect all the 1/2 or 5/8 inch ID EPDM heater hose and hose clamps you need to do this project. The hose will be dirty, and you'd probably need to clean it up, but it still should be in usable condition.

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Old 02-22-2010, 05:33 AM  
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Go with copper, I know it is UV resistant.

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Old 02-22-2010, 01:04 PM  
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As obvious as it seems, I never considered keeping the garden hose. Aside from it being yellow and contrasting heavily with the brown shingles, I could just stick with a high quality garden hose without the hassle of measuring and configuring PVC pipe. I've seen some heavy duty goodyear brand garden hose that would work. I'll just stick with that.

Too answer your question, the PVC pipe that turned brown was some standard run-of-the-mill PVC pipe for irrigation sold at Home Depot.

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Old 02-22-2010, 07:55 PM  
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Quote:
Originally Posted by ZeroAlternate View Post
As obvious as it seems, I never considered keeping the garden hose. Aside from it being yellow and contrasting heavily with the brown shingles, I could just stick with a high quality garden hose without the hassle of measuring and configuring PVC pipe. I've seen some heavy duty goodyear brand garden hose that would work. I'll just stick with that.
That's cuz you never considered the garden hose a "good" solution. You wanted to replace that garden hose with a good solution.

What's important is the hose be made of EPDM rubber for excellent UV and heat resistance. And, quite honestly, salvaged hose from your local auto wrecker would work just as well, but it just wouldn't be as pretty with joints every 4 or 5 feet.

The other option is to use ordinary garden hose and put it inside some flexible aluminum ducting. Metal is the most opaque material known to man. You can stop more light with a piece of gold leaf or aluminum foil than you can with any other material of equal thickness.



By using the aluminum to protect the hose from virtually all radiant energy from the Sun, and thereby help keep it cooler as well, then you would greatly extend the lifespan of any rubber hose.

Or, if you protect an EPDM rubber hose with aluminum ducting, that hose will outlast your house. But, if your neighbors don't know they gameplan, they may start to think you're very odd.


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