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Old 04-27-2011, 09:40 PM   #1
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Pex Manifold In Attic


I am plumbing a new house and would love to place the pex manifolds in the attic next to each water heater to save space and to make the runs as short as possible. I will have a main cold water cut off inside the master bedroom closet where the main water supply enters the house. In addition, I will have cut offs at each and every fixture/appliance. However, I am afraid of potential future manifold leaks/burst. I am using foam insulation and the underside of the roof deck will be sprayed - consequently the attic is suppose to remain within 6 to 8 degrees of the interior of the house - so attic temperature will not be a problem. I am in east Texas. What do you think? Am I crazy? Will installing the manifolds in the attic meet code since I will have a main shut off and individual fixture shut offs that are easily accessible?


Last edited by Lyndon; 04-27-2011 at 10:26 PM.
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Old 04-27-2011, 10:22 PM   #2
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Pex Manifold In Attic


Personally I'm not a big fan of having a manifold in an attic due to the potential for greater damage due to water leaks. That being said I'm pretty sure you don't suffer the same freezing temps we do.

I wouldn't feel comfortable installing one for a client, nor would I recommend it, but if you insist then I'd suggest that you go down to your local plumbing supply house and get an auto shut off valve of some type. It should be installed where the water enters your house and would monitor the flow through your pipes. If a major leak were to develop, the auto shut off valve would shut off the water supply, thus limiting the damage.

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Old 04-27-2011, 10:56 PM   #3
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Pex Manifold In Attic


I think it's worth the extra effort and little additional money to have the manifolds at comfortable working level while standing on the floor. After all, this is how all pro's will plumb a new home. I never heard of a pro installing source manifolds in the attic even if it would make things easier for them or cheaper for the contracting company.

Make the bottom of the space for the manifold "somewhat" water tight and install a drain pipe at the bottom of the space for drainage in case there's any leaks. Be sure to install a door to block all light from the pex since pex deteriorates if exposed to sunlight, direct or indirect.

Install manifolds with a valve on each output. This will allow you to shut off the water to sections of your home but not to others in case there's a leak in any pex leg. (The shut off valves at the fixtures will not help with leaks in a leg.) Then with the manifold(s) at a comfortable level, you can easily turn the valves off and on. It will also make 6 month or yearly inspections much easier. I think you would live to regret putting the manifold(s) in the attic to save labor and money now. Not to mention the damage in case of leaks, big or small.

$.02,
HRG
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Old 04-28-2011, 08:10 AM   #4
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Pex Manifold In Attic


Thanks to each of you for your advice. I knew it was a stupid idea but just needed someone to hit me upside the head to drive it in. I will indeed install them at floor level. Thanks for spending your time to help a newbie avoid a serious mistake.
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Old 04-28-2011, 09:11 AM   #5
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Pex Manifold In Attic


So, about four years ago a friend of mine, who does beautiful interior trim work, was doing a huge new home which was going to top out somewhere around $1.3 million. He told me to go up in the attic to look at the water heaters and plumbing, I was shocked. Two 100 gallon electric water heaters in the attic with NO drain pans. Four (4) PEX manifolds being fed from a common 1" supply from the city water source, then feeding the rest of the house. All I saw was potential water disaster at some later date. The later date came within two years of the new homeowners (a Nerurosurgeon) and family moving in. One of the cold water lines feeding a PEX manifold actually popped out during the day while all were out of the home. The wife came home from picking up the kids at school to see rain falling in their huge den with it's 25' ceiling. Estimated damages topped out at $325,000.
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Old 04-28-2011, 04:36 PM   #6
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Pex Manifold In Attic


Quote:
Originally Posted by Lyndon View Post
Thanks to each of you for your advice. I knew it was a stupid idea but just needed someone to hit me upside the head to drive it in. I will indeed install them at floor level. Thanks for spending your time to help a newbie avoid a serious mistake.
Welcome. Since it is your own home, you may want to install a drain at the bottom of the space your source manifold is in. Here's what I did to get the size of the drain needed for the worst case of a pex tubing popping off a fitting:

- Got an empty 3 qt. grape juice plastic container.
- Cut a small hole in the bottom of the container.
- Put a garden hose in the top of the container & turned the water on full force.
- Observed the drainage from the hole.
- Enlarged the hole until the drainage was able to keep up with the maximum flow from the garden hose.
- Then doubled the size for my drain.

In my case the box housing my manifold is outside of our house (it never freezes here). So I just cut a rectangular hole at the bottom of the box, (which is a few inches above our carport floor level), and stapled a screen to cover the hole to keep insects out. My drain hole actually ended being about 3 times the size obtained from the test procedure above.

But frankly, after seeing how well the Wirsbo/Uponor expansion method shrinks the tubing and expansion ring around the fittings, I'm 100% confident that the tubing will never pop off the fittings. I also supported every tubing near all fittings so there's no sidewards tension on any fitting to prevent the fittings from breaking.

Be sure to allow for a LOT of expansion and contraction in your hot water lines. One inch per 100 feet for every 10 degrees Fahrenheit of temperature change. Assuming your lowest ambient temperature that your hot water lines will be exposed to is 50 degrees and your hot water temperature is set to 120 degrees, that's a 70 degree temp change. That's 7" of tubing length change for a 100' run, or 3.5" length change for a 50 foot run.

Best of luck on your diy pex plumbing project,
HRG

Last edited by Homerepairguy; 04-28-2011 at 04:54 PM.
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Old 05-01-2011, 11:55 AM   #7
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Pex Manifold In Attic


Thanks for the additional advice. It is very much appreciated! Need all the help I can get.

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