Expansion Compensator/Coupling leaking

rbozzell

We recently found a carpet fungus growing in one of our bedrooms. When I pulled back the carpet and padding and traced the source of moisture, I found a small leak in a copper fitting in the baseboard that can best be described as an "Expansion Compensator" or "Expansion Coupling" - (the best pic I could find was here: ). It appears that this device is intended to absorb the expansion of the pipe/fins on long runs. But this is only about 30 ft long (it runs from a corner at one end - fairly "fixed" to a drop that is about 18" at the other end through a hole that allows for movement.

Based on some material expansion tables I found at engineering toolbox, it seems a 30 ft section would expand at most 1/2" (I assumed 150 F rise in temp from 50 at min to 200 boiler temp max). Seems like an expansion compensator is over-kill and I can just patch it with regular copper pipe. Anyone have a different view? If so, where do you get replacements or is there an alternative? The only option I found online was at Amazon and seemed poorly constructed (one review said it was prone to leak)/

hot_rod

The certainly serve a purpose to prevent noise and potential stress leaks.

What typically happens is the fin tube element will arc upwards if there is no expansion device. It also pushes the pipe connections outward. This can cause noise on the carriers inside the enclosure also.

If the piping comes up from the floor, at both ends of the fin tube the tube will move outward and possible rub and make noise in the penetration hole.

If you go without it, make sure there is room for expansion, either some plastic pipe isolators or a donuts of pipe insulation in any holes through the floor.

Outdoor reset controls can minimize those wide temperature swings and lessen expansion concerns.

Jamie Hall

All of which is why, parethetically, we don't use copper on steam lines.

Which crack is off topic.

You really do need some way to absorb the expansion without stressing the joints. Partly to avoid the inevitable noise -- and partly so that they don't fatigue and eventually leak. These are reasonably well regarded: http://www.flexicraft.com/Metal_Expansion_Joints/Compensator_S/ but I have no idea where to get them...

rbozzell

This is hot water, not steam fortunately. I did find the flexicraft on Amazon (the model no. was slightly different COMPS20075 - had an extra 0 but I think its the same), but the one review said it leaked within a week - not very promising.

hot_rod

I like the corrugated stainless type better, no o-rings involved. This company is from the UK.

And another o-ring type.

If you have access to some SS flex it is easy to fab a flex coupling. I brazed the copper into the stainless flex for this example. Be glad to send you one if you can't find any options. These are commonly used in the solar industry.

EBEBRATT-Ed

Call Tunstall Assoc., Chicopee, MA. They have good flex connectors