Heat loss of bare pipe...JohnNY

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JohnNY

Where can I find...

...heat loss of bare pipe online?

I just looked at a job this morning in a Manhattan loft where the customer wants bare copper instead of radiators. Says he doesn't care how much tubing it takes. Several tiers along the perimeter walls is what he's expecting.

The space is 1800 sq.ft. with full length picture windows on two sides.

It's actually a radiant job, isn't it?

Interesting project. I'm looking forward to it, but I need to do some math.


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Larry (from OSHA)

check out

the hot tech topics section of this web site. about half way down you should find what you are looking for. Lots of other good info there too.

Larry

Mad Dog

Sounds like he wants you to build a good ol'

pipe coil radiator. That is a lot of fun. Can't tell you which book, but one of Dan's books, but it has the output...also, the Burnham Heating helper book should have it. If all else, steamhead or Noel will know. MD

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hr

If

you had a 200 foot run of 3/4" M copper. A 1 gpm flow of supply water at 180 degrees, exit temperature of 160.4, and the surrounding air temperature was 65F you would get 9813 BTU/hr.

A pretty small amount of heat compared to fin tube element! Of course the output drops as the surrounding air temperature increases 9299 BTU/hr at 70 ambient.

Keep in mind additional loops seeing lower water temperature would have less output.

You need fins to get additional convection or more surface area, like a panel radiator, to gain more output.

What is the heat load and how much spare wall space do they have? And who will keep that copper looking shiney and dust the tubes? Let us know how you proceed.

hot rod

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Uni R

Bare Copper Heating Pipes

Does he realize what copper is going to look like in a few years? Does he know the difference between brass and copper? A four high horizontal run of large diameter brass would look awesome! The pipe is going to have to be impact resistant so it'll need some wall thickness.

Mark Eatherton1

Bare copper may be pretty...

but it doesn't emit heat for crap!

Remember my copper plate ceiling hung heater in my office... The one that I painted flat white and doubled the output of the heater...Yeah, that one!

If it were me, I'd consider doing radiant walls and keeping the temps low, like below 150 deg F.

Or how's about this. You do a 1/2" grid in copper, 5" O.C., snap extruded heat transmission plates onto the 1/2" copper pipe, and "fix" sheet copper onto the aluminum with some of those Epoxies like Dale Pickards using, and...

Viola!

Instant artsy fartsy panel radiators with Phunction!!

NAH..it'll never fly:-(

Happy "Think outside of the box" hydronicing!

ME

JohnNY

Thanks, ME.
Unfortunately, radiant is off the table. Copper and stainless steel are huge in interior design these days and the guy with the money knows what he wants, i.e. lots of functioning copper tubing on the walls.
His staff of many will be responsible for keeping it pretty. I have to make it work and put it in neatly.

I still can't find that per foot information though.

WHERE THE HELL IS MY HEATING HELPER??!!
I swear those things grow legs.

Another thing I'm trying to figure out is:
How much consideration should I give for the radiant effect of all that exposed copper?



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Unknown

Here you go Johnny Boy

One way to never lose the Heating Helper - download it .

http://www.burnham.com/pdfs/htghelper.pdf

I know what you mean , I lost at least 3 of those booklets .

It says a 3/4 inch tarnished copper pipe at 180 degree water will give you 45 btus per linear foot . I hope theres plenty of wall space for the pipe - I bet it'll look amazing when it's done .

Whats going behind the copper on the wall ? Would some sort of reflective insulation in the wall behind the plaster or sheetrock help spread the heat some ? Post some pics when this one is done .

Edward A. Carey

Bare pipe

John,

One more thing to consider is the safety issue. In floor Radiant or fin tube copper inside baseboard is protected from contact by the HO. Wall mounted radiant will have lower water temps than the exposed copper pipe.
Exposed copper pipe is EXPOSED.

If they have any little children around there could be a problem. If they don't have any children, they must have friends or relatives that do, and they would even be less aware of the problem.

A large quantity of exposed copper at a surface temp slightly below 200 F, (containing 200 degree water) could be be a real problem.

What would be done to protect people (especially little ones) from contact to the surface of the hot bare copper?

Just a thought,

Regards

Ed

JohnNY

Thanks a lot, Ron.

It seems I can always count on you.

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Uni R

Heat loss...

Those numbers are going to be overstated. Those calculations are one length of pipe going through the air at temp X. With a bunch of other nearby pipes giving off heat, there will be less heat transfer. Those other pipes are warming the air already so the transfer rates will be lower.

Unknown

Thats why the numbers

are for linear feet . Do you have chart or maybe a reference book that will give some numbers if John stacks the copper pipe ? Hey , what about stacking them on an incline ? Like have the highest pipe close to the wall , next row 3/4 inch farther out , and so on ....

Uni R

Nope - no chart

Ron,

I just wanted to give a heads up on that. The numbers are by linear feet but linear feet going through the air at a certain temperature. If other pipes are nearby and heating the air, there should be less temperature difference between the air and the copper pipe so there should be less transfer.

Those would be some wicked tables to calculate! Distance between horizontal rows would be a factor as would different airflows in different directions for all of those different spacings...

I'm not an expert but just thought that going straight by the heat loss charts might cause the radiation area to be undersized.

The incline would defintely help... especially if the lowest ones went under the floor. Woops... That's not what the customer wants.

Maybe John should sell him on the idea of both infloor and the tubes. The tubes would look amazing and could form a few rows under the windows but I'd be looking at big tubing. 2 or 3" rather than 3/4 and with thick walls so that they don't ever get dented. With the infloor the wall tubes could be kept under 140° which would probably please the homeowner's insurance and lawyer and the floors would be warm.

JohnNY

I'm thinking something like this with reverse return:

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Uni R

Have you considered...

Have you considered any of the high end companies that build hydronic towel warmers? They may be able to do custom sized ones that are low and really long like what you pictured and also help with ensuring that the heat loss design is adequately covered. Even with that staff to keep them all buffed, I'd still be really concerned about material selection.

JohnNY

Pipes

Client wants copper pipes.

Why would you be so concerned about the material?


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Pension Lover

John,

I just read the traffic on your request for more information on the heat loss of bare pipe . . . it sounds like your client is looking for a piece of art that happens to supply heat. It's a nice compliment.

After calculating the heat loss (of the pipe size you and your client decide on) why not design your work of art with a combination of functioning and non-functioning pipes?

Locate the empty pipes of your sculpture in the areas that are within human reach and the functioning pipes a little higher. Even then, the working pipes can be separated by the 'dummy' pipes so as not to have too many functioning pipes warming the air in too close proximity to each other.

Jim Glose

Lori

If the pipes alone won't deliver enough BTUs, you might consider a reverse panel ... i.e. the conducting/diffusing surface on the wall behind the pipes, with the pipes in contact with it. That might up the output, and/or allow lower water temp if safety is an issue.

Larry Weingarten

finned copper tube

I'm using finned copper tube made for use in solar collectors for radiant wall heating. The Copper Development Association and ASHRAE Handbook have some good info about heat output of bare copper. Northstar Gardenia in S. California made the tube.

Yours, Larry

Mark Eatherton1

that's only

49 btuh/linear foot?

I've heard the number 150 bantered about per foot for years but have nothing to back it up with.

Pretty sure the Burnham Heeating Helper has that info in it.

JohnNY, what I was getting at is that shiny copper is a terrible emmiter of heat as a RADIATOR. There are two primary components of heat transfer with bare pipe. Theres the convective capacity, and the radiant capacity. The radiant capacity is pretty much nul when copper is shiny. It doubles when dulled or painted some color other than metallic.

Let us know what you end up with.

ME