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pex versus copper
Al Corelli
Member Posts: 454
That copper is so nice, I'd have put down plexiglass floors.
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Comments
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Heat transfer
If heat transfer is important than why use pex over copper I was under the impression copper has 8 times the transfer compared to pex? Also heard that copper will build heat simply from running water thru it, cant get it from pex or am i totally off base here.0 -
Copper is impractable to work with in some cases like infloor etc... also the cost.
i like copper better, but I am on the sales side i don't have to in the field, run a line from a boiler room on the other side of a building to a new addition, in that case pex is better. But for the near boiler piping I find the the installers like copper or steel because it looks more profesional.
The flow risistance in pex is quite a bit higher than in the euivalent size of copper as well(ID is smaller)
Good Luck,
Bob0 -
Pex does have reduced transfer compared to copper, but as Bob says the labor involved with doing copper radiant makes it pretty impractical, and PEX is certainly "good enough", as evidenced by all the radiant going on0 -
as the other s said plus:
although you may get better transfer from the copper the bottle neck is then the next material, as in plywood.
so if the plywood has a poorer transfer rate than pex, the plywood is the bottle neck and copper would NOT make a difference in heat transfer.
weakest link in chain theory. you can have a superior heat transfer system, lay down a thick carpet and bang, cold room.0 -
Resistance to heat transfer is cumulative, this is not strictly accurate. Each layer that must be penetrated adds its resistance to the last. Reducing resistance to any layer would improve heat transfer.0 -
Sure copper
is a much better conductor of heat. I've used copper in concrete and also aluminum transfer plater. The difference is quite noticable. Copper in ThermoFin is the dragster of heat transfer. almost instant heat output.
I've not seen soft coil copper in lengths longer than 100 feet. That's one drawback. Cost, workability, expansion issues... Doesn't get along with some concrete admixes. All things considered it is not a very pratical option.
hot rod
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Would any one here go with copper in there own home if they were to install it and granted pex has its places,I won't argue there. With prices on copper these days it doesn't help. So for the sake of the prices what would you do. (Price not being an option)0 -
first tell us
what type of application you have in mind?
I have seen copper in extruded aluminum transfer plates actually cause the plate to warp up into an arc. I'd worry about expansion noise with that kind of rapid movement. The pex, by deafault, warms the plates slower.
I think you would want to keep the loop lengths short I have done a few experimental copper/ transfer plate jobs. All exposed so they could be "modified"
I'm not sure I would trust copper in concrete with all the fillers they add these days. Why risk an un-repairable tube failure?
hot rod
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Not to mention
The quality difference of the copper we get today compared to what we bought 20 years ago is staggering. We just did some overhaul and changeout work in a house that had been remodeled in 1980. Some 1/2" type L soft copper had to be removed and when the boys and I were pulling it out, it was remarkably workable. Easy to bend yet despite being in use for 26 years. You could take the stuff and bend it multiple times without it becoming "work hardened". Forming a 6" radius bend in it by hand was no sweat whatsoever. The new stuff we put in (Wolverine) was a different case altogether. Once it was bent it was nearly impossible to rebend into another shape and bending it the first time took some serious effort. Copper isn't what it used to be. I think the term "soft copper" is becoming an oxymoron.0 -
Before the jump!
These were from my kitchen remodel last winter. Before copper became a precious metal. At that time for me to invest in the tooling to do it in pex, and plates was more donaros than doing it in copper. Also I kept in tradition with the rest of the radiant in the house.
I experimented with heavy gauge aluminum foil as plates,to see if there was a noticable difference in added heat transfer... there is. I had to back butter the backer board with thinset though. This was done 8" on center.
Gordy0 -
Really Nice Work, Gordy!
Did you use a Curvo? Beautiful bends, nicely thought-out and laid out, I can feel the warmth from here. Shame you had to cover it up.0 -
Copper
Brings tears to my eyes what an awesome job. And to think there is a person who believes in copper for that type of job.After putting down 47 rolls of copper in my basement floor and a snowmelt for the walk out,all hand bent and brazed i have to say what it is,truly remarkable.0 -
Thanks ,Brad and Joe
No Curvo, all by hand. Kept in tradition with the dead men in my Chase copper,and brass brochere from the radiant ceilings in my house. They earned their money!
It was interesting to notice the difference in the workability from roll to roll of type L soft copper Mueller brand. I had my best luck standing the roll up on edge and walking it in.
Gordy0 -
Copper vs Pex
Maybe I am having an early senior momemt here but aren't we talking about initial heat transfer rates? Once temperatue is achieved in thermal mass I would think that the insulation below the slab, confining envelope insulation or "R" values are more important than delivery rates.
Hot water systems other than in-floor may be a different story as one may want fast delivery with copper fin tube etc. Copper fin tube while having fast delivery also has fast cooldown creating differential problems.
Sorry old timers I would be hard pressed to go back to copper in an in floor installation. the prettiness is only temporary.
Kudos for your workmanship though, brings back memories.
Rich K.0 -
Senior moment
I would have to say your not having a senior moment.... But I will say that the faster the Btus are transfered, the sooner the T-stat gets satisfied along with the occupant.
Matter of fact the speed of btu transfer to the space is a part of the systems efficiency. Unless of coarse we are talking about Btu losses of the structure.
Gordy
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Plexi glass
Thanks Al hmmmmm plexiglass floors. Next room, Wonder what the Mrs. would do.
Gordy0 -
47 ROLLS !!
Holy crap Joe you did'nt mess around. Got some pics.
Gordy0 -
Here is some...
... finned copper in wall. It works nicely ;~)
Yours, Larry0 -
What about heat retention isn't that factored in? especially when you have good thermal mass in gyp-crete, tile etc. Dead cold to heated area copper wins,once thermal mass is warm I believe there would not be much of a difference.
Take a farmhouse that has a mix of fin-tube and old standup radiators(cast iron) copper distributes faster but loses heat faster also.0 -
Thermal mass
I think we are talking about micro issues. But once a mass is heated to a given set point, and then starts to cool be it pex or copper I would think the object is to transfer heat to the cooling mass, not retain it in the tubing.
Keep in mind I'm not saying that the industry needs to stick with copper tubing. I think there were plenty of arguments above against its use.
Mostly for labor intensive issues, and Pex has the longevity in a variety of caustic enviroments. All though I think copper in a good enviroment, right PH, proper concrete mixes ect. Can be a very good product to stand the test of time.
Mine has been in place for over 54 years with out any problems so the enviroment for my copper must be good, or I'm very LUCKY.
If I were a pro installer I would use pex it is the only way to be efficient,and competitive. My kitchen project was only 300 sq. ft.
My plan is as I remodel floor coverings through out my home I will install radiant floors sleeper style. As long as the ceiling radiant holds out I will enjoy a radiant sandwich (ceilings and floors) once the ceilings see thier life span if, and when. I can abandon that system, and go to the radiant floors. So I must design the radiant floors to meet the heat losses on its own. Until the ceilings die I suspect I will enjoy some very low supply temps. to meet the loads.
Gordy
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We basically agree
Overall from a cost effective standpont pex is presently the best material.I too have seen and serviced the copper systems that came into play after WW11. Well installed and maintaned copper systems are still functioning, yet at 50 plus years they are reaching the end of there servvice life.This is a great track record.
Price of copper, labor involved and current methods unfortunately make it obsolete.I have read and anticipate long service life for embedded pex as it has gone through rigourous testing (per Wirsbo School Data) yet only time will tell when field conditions are the test versus more controlled in-house factory testing.
I have done homes where the owner still wants black pipe, cast iron fittings and CI radiation(if they have the $$$$$ we have the time!)
Thanks for the responses (always curious)
Rich K.0 -
You miss the point.....Pex is not good at transfering heat. That is why it is great to run hydronics..feeding radiators air handlers, floors..whatever. This way the heat gets to where YOU want it. In the case of radiant floor heating the slab, the thermal mass is what draws the heat out. or we create a different means- aluminum such as raupanel or if under in a retrofit situation- extruded aluminum heat transfer plates. THis draws the heat well and very evenly and spreads it out uniformly accross the floor. we can run a couple hundred feet then head back to the manifold. If copper you are giving up heat in leader lengths and other places not directly to the floor where you want it. Also if you transfer it to quickly you are going to have very un even temps accross the floor unless you build a manifold on either side of the room supply and return just one bay at a time.
I guess that is why some people do joist bay heating they think Pex is just a radiant floor tube and is great at heat transfer (not the case). Shame on some of the pex manufacturers teaching joist bay at their classes especially when they have guys just getting in to radiant in front of them who don't realize low temp and conduction is the name of the game.Getting the end user an extremely efficient system, burning less fuel in this country (world) not just keeping their big foot toasty.
The copper would cost more, a lot more labor, doesnt have the same life span and will not work nearly as well.
Aluminum not only draws the heat out extremely well it gives up the heat readily. Heat up a piece of copper and aluminum wait 60 seconds pick them both up see which one burns your hand. Extruded aluminum helps us to take a lot of the lag out of radiant floors on the warm up side and keeps us from over shooting when the flow stops.0 -
yes i do will post some in the near future as i'm computer un savy with the pics will have better half do it.0
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