Approximate heat loss for bare copper pipe at 160 degrees F.

lsayre · Post by **lsayre** » Sun. Jan. 20, 2019 7:36 am

Per foot:

1/2" = 40 BTUH
3/4" = 49 BTUH
1" = 68 BTUH
1-1/4" =80 BTUH
1-1/2" = 92 BTUH

For my case, our homes zones average roughly 135 feet in total length, and each zone has on average 41 feet of 3/4" hot water baseboards.

135 - 41 = 94 feet of bare 3/4" copper pipe
94 feet x 49 BTUH/Ft. = 4,606 BTUH

If my hot water baseboards emit a nominal 550 BTUH per foot, then on each of my zones my bare copper pipe is adding roughly an additional 8.37 feet of "baseboard equivalent".

4,606 BTUH/550 BTUH/Ft.= 8.37 Ft. of baseboard equivalent

So effectively, each of my zones has (on average) 41 ft + 8.37 ft = 49.37 feet of baseboard equivalence.

Excluding the garage, and considering our 3 home heating zones:

3 x 49.37 Ft. x 550 BTUH/Ft. = 81,460 BTUH of radiators in my house (or roughly 32.33 BTUH per sq-ft).

coalkirk · Post by **coalkirk** » Sun. Jan. 20, 2019 1:19 pm

You are not losing that heat. All the bare copper pipe is in your home. Put your slide rule away and enjoy the warmth.

CapeCoaler · Post by **CapeCoaler** » Sun. Jan. 20, 2019 1:28 pm

But sometimes ya just gotta play with numbers for the sake of it...
Rocket scientists and Nuclear engineers...
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LOL...
Made a rocket out of two soda cans and a small fire cracker....
The Nuke engineer was entertained for hours...
The shear simplicity of it...
Then he proceed to modify it...
Nose cones, tail fins, ballast, multiple stages...
LOL...

lsayre · Post by **lsayre** » Sun. Jan. 20, 2019 1:52 pm

My calculations indicate the utilization of this heat as effective feet of HWB's. I tossed this out there for anyone considering HWB's and copper piping. I do not know the heat loss for PEX, or I would outline that also. It is likely well less than that for copper.

wilder11354 · Post by **wilder11354** » Sun. Jan. 20, 2019 2:57 pm

This is what i used on copper pipes under house. House is on columns, and skirted. No Full foundation.http://www.industrialinsulation.com/images/fiberg ... 032018.pdf. Was looking for the website where i bought. Did notice price has gone up about double from when i got it 4 years ago.

lsayre · Post by **lsayre** » Sun. Jan. 20, 2019 3:47 pm

That's premium stuff there. My problem is finished ceilings in the basement and garage. I'm not changing anything due to that, and due to likely benefiting from the heat from most of the bare pipes regardless.

McGiever · Post by **McGiever** » Sun. Jan. 20, 2019 5:29 pm

Are the heat loss numbers all equal if bare copper pipe in a open ceiling vs being in a closed or confined cavity above a finished ceiling?

lsayre · Post by **lsayre** » Sun. Jan. 20, 2019 5:52 pm

McGiever wrote: ↑
Sun. Jan. 20, 2019 5:29 pm
Are the heat loss numbers all equal if bare copper pipe in a open ceiling vs being in a closed or confined cavity above a finished ceiling?

No. As the temperature differential between the surrounding air and the pipe surface diminishes, the quantity of BTUH evolving off of the pipe diminishes also. And visa-versa.

The figures I gave in my first post are for roughly 85 degrees of difference between surrounding air temperature and pipe surface temperature.

McGiever · Post by **McGiever** » Sun. Jan. 20, 2019 11:24 pm

How about bare copper pipe in a open drafty space at 85* vs a sealed above finished ceiling dead air space at 85*, still same?

lsayre · Post by **lsayre** » Mon. Jan. 21, 2019 3:22 am

McGiever wrote: ↑
Sun. Jan. 20, 2019 11:24 pm
How about bare copper pipe in a open drafty space at 85* vs a sealed above finished ceiling dead air space at 85*, still same?

I'm not sure. My intuition would say that for this specific case the enclosed ceiling might more advantageously direct the heat to beneficial living areas above (vs. having some of it go out the basement walls), but I'm also aware that more often than not intuition makes for bad science. What is your opinion on this?