"David Lesher" wrote in message ...
Jeff writes:


Leaks really aren't a problem in underfloor staple up systems. The
runs tend to be in one piece for each room.

I believe the better underfloor systems use not "rubber" hoses but
PEX (cross linked polyethelene with oxygen barriers) with heat spreaders.

Leaks in hydronic (water-based) floor heating systems used to be a big problem :
In the 60's, many hydronic floorheating systems were installed using copper pipes inside concrete slabs.
It took 30 years but most of these systems eventually start leaking at the pipe joints inside the concrete causing very tricky
leaks.
Leaks in piping in concrete is hard to locate (use helium gas detection method), you need to rip up your flooring, and jackhammer
into the concrete and fix the broken joint.
Very expensive leaks indeed.

Luckily, life got a lot easier with PEX (cross-linked Poly Ethylene).
Apart from being probably the future for all residential plumbing in general (replacing expensive copper plumbing), PEX is almost
ideal for hydronic floor heating systems.

PEX is very, very stable (corrosion free; lasts longer than your home), can handle high pressure if that may occur has flexibility
but is not 'floppy', so it is easy to install and it is much cheaper than copper too. Typically hydronic systems have a continuous
PEX loops, so that there are NO joints in the tubing that is under the floor. This again reduces chances of leaks, since leaks
typically occur at joints.

Basically the only way to get a leak in a correctly installed PEX hydronic system is if you drill into the floor (and into the PEX
tubing) or jam a nail through it. PEX is sturdy, but it cannot handle nails and drillbits.

Once you have a leak, it really depends on how accessible the tubing is if it is costly to fix or not.
If the tubing is inside a poured concrete slab, then fixing it is difficult and expensive.
If the tubing is 'staple-up' underneith an existing wood sub floor, then there is access to the tubing, and fix is easy.
If the tubing is in a 'sandwitch' on top of a sub floor, then of course you need to remove flooring to fix it, so it is difficult.

I have installed a hydronic floor heating system (with PEX tubing) in a sandwich on top of an existing concrete slab sub floor.
Installed 2 years ago.
It's working great, and the PEX tubing was not a problem at all to install.
Risk of leaks is only there when people start drilling into the flooring.

Pictures below


Actually, the better installations I've seen have 2 interleaved runs
for a room. The idea is: if in fact one leaks, the other still handles
the room...

Actually, the interleaved runs are called 'counterflow' loops.
Counterflow loops minimize temperature differences on the floor, by placing inlet and outlet of a loop next to each other.
Multiple loops in a room are needed for pretty much any reasonable sized room, since the temperature drop limits the length of the
loops to about 250 feet.

I've never heard about installing loops so that one still works if the other is leaking. If anything leaks in the system, you want
to fix that before continuing. Unless you want to risk wrecking your hardwood (or whatever else you have installed on top of the
floor heating).

Here are pictures of my (PEX in a sandwich configuration) system under construction.
Some pictures also show counterflow loops with

http://viper.verific.com/WebSites/RadiantFloor

Regards

Rob

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