Heat Loss - Qualpex vs Copper

championc

Hi all,

Are there any figures available as to the heat loss from each of these pipes. Given that Copper is an excellent conductor, it occurred to me that it could also be best at transferring cold air surrounding hot water pipes into these pipes.

I was thinking recently after using a hot tap that 10 mins later, I should still have had a bit of hot water remaining in the length of pipe but it was cold. Obviously, this would also apply to central heating pipes. The only place you want to release heat is in the rads

Any views or stats ?


C

mossie110

this makes no sense to me
http://www.engineeringtoolbox.com/copper-pipe-heat-loss-d_19.html
next,, i took this of the net
If you insulate a piping system, which you have to do if you want an energy-efficient building, I don't think there could possibly be much difference beween the heat loss from MDPE pipes and that from copper or stainless steel pipes.

Suppose that a pipe has a wall thickness of 3 mm and that this is a plastic with a thermal conductivity of 0.17 W/mK.
The R-value of the pipe wall is 0.003 / 0.17 = 0.018 m2K/W.
Suppose that the pipes are then insulated.
The R value of 40 mm rigid mineral fibre is around 0.04 / 0.034 = 1.18 m2K/W. This is about 60 times as much.

championc

My pipes have NO insulation. So without insulation, how do they compare ?


C

items

I've no figures but from experience I find copper heats up quicker. I would'nt say their is much of a difference between the two, changing hot water pipe work to pex wont really hold heat enough to make the job worth while.

Insulating as much pipe as possible is best, their is high grade insulation available, mostly refrigerant company's use it to stop pipes from building up frost. It's the best stuff out there.

If your having a problem with dead legs, drawing to much cold water before hot comes you can fit a secondary return into hotwater pipe work. This is normally done when hotwater cylinder is (x) far away from house / taps. To do something like this means adding an extra pipe to hot water circuit and teeing into furthest hot tap. You'll need a cylinder with provisions for secondary return along with a broze of stainless circulation pump.

The idea is simmilar to heating only its fresh hot water that circulates around the house, circulation is controled by a timer. Secondary return is mostly used in large buildings like hotels, hospitals etc but I've fitted a good few in houses 4 to 6 thousand square foot in size, any less than that might be overkill.

youtheman

Copper is obviously a much better conductor of heat than qualplex, but the wall thickness of both pipes is so thin that in reality there will be very little difference in the outside temp of the pipe. Now if the wall thickness was a few inches then that would be a different matter. But a few mm will make sod all difference.

championc

Many thanks for your views.

I suppose the next question is as to whether it's worth retro fitting lagging onto pipes that currently have none. What I'm getting at here is, if I have some runs which may be a tad difficult to get to (but do-able with effort), is it worth lagging them with the foam tube stuff. And then, is there much difference between the standard cheap foam stuff and the high grade insulation ? What make is the high grade stuff (for 1/2" and 3/4" use) ?


C

Outkast_IRE

championc wrote: »

Many thanks for your views.

I suppose the next question is as to whether it's worth retro fitting lagging onto pipes that currently have none. What I'm getting at here is, if I have some runs which may be a tad difficult to get to (but do-able with effort), is it worth lagging them with the foam tube stuff. And then, is there much difference between the standard cheap foam stuff and the high grade insulation ? What make is the high grade stuff (for 1/2" and 3/4" use) ?


C

The higher grade for domestic that i usually come across is usually armaflex thats recommended .