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i_am_chris
02-01-2010, 07:03 PM
Hiya,

We have our radiant floor system running and are experiencing an unexpected issue.

At this point, we have only one of the three zones running, though the entire system has a blend of water & glycol antifreeze. Two of the zones are in buildings we aren't using yet. The third zone, which we are using, is in a building 500+ feet away and 130 feet downhill. We used vendor-supplied 7/8" pex for our radiant floor lines as well as domestic hot and cold water supply lines to this same building, with Viega 3/4" pex used to connect to non-vendor fittings.

We ran the domestic hot and radiant heat supply lines in one paired run, wrapping foam rubber insulation around both lines and surrounding these in "corex" drain pipe underground. This was to keep the two lines carrying heat as warm as possible. We have the radiant heat return line paired with the cold water supply line, again wrapped in one foam rubber insulation piece and in a shield of corex.

In this zone, we've found that the hot water/radiant heat supply lines are sagging, shrinking, or something. The building that houses our manifolds and pumps (we have no basement) is where we noticed the problem. The vendor pex pipes are slowly dropping through the floor. Weird thing is, at the Zone 3 building, the pipes aren't pushing out the other end of the corex - they come right up to the floor and turn to the various loops. So, its like they are shrinking, buckling, something!?!

We haven't found any leakage, the pressure is stable, the system works. Have you heard of anything like this? We have twice added additional sections of pipe in our utility buildling, because we don't want to try pulling the lines back up and risk somehow disconnecting the pipes underground, which would be a serious hassle to fix. Any ideas or suggestions would be appreciated.

Can provide more info about the system, how we're running it, etc.

Chris

Mike44
08-17-2010, 09:48 AM
Hi Chris,

A few houses in my town actually had PEX plumbing pipes installed when they were built (probably about 10-15 years ago now) including my house. In some of the older homes, there have been issues of "sagging" pipes on the domestic hot water lines. The tops of the pipes feel depressed or slightly flat as if they are caving inwards. I've been told that it has something to do with the inner plastic wall or something. I can't really be sure exactly as I am not a plumber myself, but this is just what I've heard from the plumber that installed them while we were working together in a new house. I hate to be the bearer of bad news, but some of these people have already had some issues with leaking from their hot water lines and as a result have actually needed to get those lines replaced. It could be a progressive issue, with the sagging/shrinking/buckling being the first indication maybe???

I'm not saying that this is what is happening with your pipes, but it could be starting. I've been checking my pipes every so often since I heard this; so far so good, but we were also near the tail end of PEX usage, so it could still just be a matter of time.

When did you install your system?

Mike