Best Material to Use for Drainpipes in Residential Homes.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1855345#Comment_1855345

I've experienced this issue with copper piping in my house from the water heater, as well as steam runouts.

But never pvc drains or pex piping honestly. Both tend to be soft and slippery materials.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1855346#Comment_1855346

Had to put that in metric eh…

hot_rod

2X4's keep shrinking. This recent purchase is barely 3-3/8.

The pipe is 3-1/2, its OD doesn't shrink like the lumber :) We typically drill a 3-5/8" hole for 3" PVC or ABS.

The only time we dealt with expansion and contraction with slip couplings was log home. The logs shrink and the home settles, so vertical piping had O-ring expansion couplings, or a Fernco with a gap.

A pic of cell core PVC

mattmia2

is that the home depot special? as far as i know the haven't shrunk since about 1970 when they went from 3-5/8" to 3-1/2".

The pvc drain for my laundry tub makes lots of noises when you run hot water through it.

The coefficient of expansion for pvc is about 3x that of copper and copper is a little less than twice that of steel.

ethicalpaul

it is like any other piping material, you have to…

ok cool, the way I read it sounded like PVC was worse than others

mattmia2

https://forum.heatinghelp.com/discussion/comment/1855354#Comment_1855354

much worse. that is why vinyl siding is an engineered system that allows all the pieces to move a significant amount. the ends go in to channels that cover the gap and the pieces themselves are hun with the nail in a slot that lets the panel move.

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1855349#Comment_1855349

that was the reference I found. 10c is 50F I think

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1855355#Comment_1855355

sorry I keep getting confused. You said it’s just like all materials—it must be supported and installed properly. 7mm over 10 meters per 50 degrees F change doesn’t sound scary to me.

Pipe isn’t siding which can go from -20F to probably ~200F in the sun

hot_rod

In all my years of plumbing we never did anything special for PVC or ABS expansion. At least in residential installations. 70° ambient to maybe 105- 110° drain water temperature is common. So not a lot of movement. Maybe the dishwasher discharges hotter water for a brief period.

The metal roof makes more expansion contraction noise than the plumbing.

I imagine vinyl siding often sees a much wider ∆

mattmia2

the ambient in the dark corners of the basement in winter is probably more like 50f, the water from a shower or washing machine or dishwasher or hot water faucet is over 100f so delta t is more like 50f. All common materials will make noise if you don't compensate for expansion.

The coefficient of liner thermal expansion for:

Steel ~12*10^-6/K
Copper 17*10^-6/K
PVC 52*10^-6/K

So if you have a piece of pvc 10' long and change its temp by about 50f it will change length by about 10ft*25F degrees *52^-6*/K ~= .013 ft ~= 3/16"

1 Kelvin/Celsius degree is 9/5 of a Fahrenheit degree which is close enough to 2 for estimation.

3/16" is a fair bit over a 10' run and longer runs will be proportionally more. If it can't move it will buckle or make noses when it finds a way to move.

Technically it is 3/16 inch 2 Fahrenheit/Kelvin 😄

Mad Dog_2

Cell-Core PVC looks exactly like regular PVC, just much lighter in weight. Mad Dog

Mad Dog_2

Guys were using the Cell-Core Foam Core for Mod Con exhausts and they were degrading quickly. That seemed to be the time, they outlawed regular PVC as well. Mad Dog

Alan (California Radiant) Forbes

No-Hub cast iron has always been the top shelf material here and of course, the plumber installing it has to be of equal quailty as well.

No-Hub cast iron drains, ABS vents. For commercial work or houses over two stories, the materials had to be all metal, so we used DWV copper for the vents.

In the beginning, we used a chain snapper to cut the cast iron, but then transitioned to a chop saw as it was faster and the cuts more accurate.