Replies

1. 
   fingers | Oct 11, 2009 01:59am | #1

   Why not? If you use pex make sure you know where your nails are going.

2. 
   DonCanDo | Oct 11, 2009 02:04am | #2

   Why not just build a small soffit?

   It would be easier than trying to deal with the corners of the room (assuming the crown molding goes around the whole room).  If the crown doesn't go around the whole room, it would look odd.  Also you're talking about some pretty big crown molding to get the pipes back far enough that you can be sure of not nailing into them.

3. 
   ms | Oct 11, 2009 02:49am | #3

   Don's got the right idea. My plumber and I just looked at a similar project yesterday. The pipes will run along the ceiling and wall joint of which the wall has limited insulation. My plumber would like to see some perforations,(I haven't thought too much about this part yet),in the soffit to insure the warm interior air can circulate through. He calculated that 1X4s at butt joined @ 90 degrees would be enough room to accomodate the 2 pipes.
   Mark

4. 
   DanH | Oct 11, 2009 03:31am | #4

   In Minnesota pipes in the crown molding would still be in danger of freezing, in a serious cold snap, so I assume you live somewhere warmer.

   The main problems are:

   -- Getting crown big enough to hide the pipe (though you could presumably notch the drywall to gain a little more space). Remember, the pipe (especially copper) will not necessarily want to lay tight against the wall for its full length.

   -- Avoiding nailing the pipe. Even copper is easily punctured with a nail, and PEX is worse. (Thankfully few people hang pictures from the crown anymore.)

   -- Managing corners. A soldered copper elbow would ALMOST be compact enough (would likely work if you hogged out the wall a bit and also hogged out the back of the crown), but PEX can't normally bend that tightly.

   As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
1. 
   Dam_inspector | Oct 11, 2009 04:54am | #5

   Use a pex elbow in the corners.

1. 
   DanH | Oct 11, 2009 05:25am | #7

   Except that some of the clamps I've seen take up extra room.
   As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz

1. 
   Dam_inspector | Oct 11, 2009 05:34am | #8

   The copper ring is fairly small, but you're right about the stainless clamps. I wouldn't run pipe behind crown myself anyway, but it would probably work OK.

5. 
   Dinosaur | Oct 11, 2009 05:11am | #6

   Hiding pipes behind crown moulding is an overly-complicated idea, and to do it you will probably have to work twice as hard as you would to build a ventilated soffit.

   In addition: Pipes up against walls or ceilings that separate heated space from unheated space must be left exposed to the room air...or they must be hidden in a ventilated pipe chase or soffit. Otherwise they will freeze in bad cold snaps. One serious mistake many people make is to think that insulation will prevent this; in fact insulation can actually make things worse because it slows room heat getting to the pipes just as well as it slows heat in the pipes being sucked out by the cold.

   The pipe chase or soffit doesn't have to be big; for two ½" copper pipes, a 2" x3" space would be sufficient...although a 3" by 6" soffit might look more like something you planned than something you had not choice but to build.

   You can buy plastic grid intended for fluorescent light boxes in commercial drop ceilings; it makes good soffit or chase vents.

   Dinosaur

   How now, Mighty Sauron, that thou art not brought
   low by this? For thine evil pales before that which
   foolish men call Justice....
   

   

6. 
   WonderWoman | Oct 11, 2009 06:15pm | #9

   Why not keep the pipes in the attic but bring them down next to the ceiling and put all the attic insulation above them, no insulation between the pipes and the heated space? Make sure the space they run in the attic can get heat from the rooms below, maybe make openings in closet ceilings or other hidden areas to let heated air up.

1. 
   DanH | Oct 11, 2009 09:42pm | #10

   Or one could actually build a heated pipe chase in the attic, with insulation above/around it and a little airflow through it.
   As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz