Near Boiler Piping

Tim_24

of copper is almost ten times that of carbon steel. How can steel pipe lose more heat than copper? In addition to reasons for using black outlined above, the themal expansion of steel is less than that for copper, causing less problems and failures.

Joe_55

Near Boiler Piping

Would appreciate any opinions on this, I have noticed many non-C.I. hot water boilers (munchkins etc.) piped with Black iron "in my opinion time consuming" compared to using copper pipe, But my main question,Will all that heavy gauge iron pipe not put an extra heat load on the boiler compared to thin walled copper especially if not insullated? Which approach do you recomend?. Thanks Joe.

Tim_24

Insulated piping..

will not sigificantly add to the load on the boiler regardless of the material. Black pipe around a boiler is much more resistent to physical damage and can support the weight of system components like an air sep/exp tank combo, inline circs, etc., where copper and sweated joints, especially at temperature, must be supported and is more subject to damage.
Opinion: support and protect the copper or use black pipe.

Mike T., Swampeast MO

You are correct. Black iron (steel) piping will loose more heat than copper-thus the piping creates more load for the boiler. Not only is the OD of copper smaller than the same size iron (steel) but the emissivity of black iron/steel is greater than copper in any normal condition. (Copper can be exceptionally emissive--think green...)

Mike T., Swampeast MO

Bare pipes loose heat via convection and radiation.

Since the pipe itself is heated via the forced convection of moving water, the outer temperature of either type will be nearly identical. For the same nominal size, black pipe has a larger outer diameter than copper tube. More surface area = more convection.

Radiation is highly governed by emissivity. Black pipe is highly emissive. Copper however has extremely variable emissivity. When polished, it's extremely low. When heavily oxidized and nearly black emissivity is near that of black pipe. Only the green oxidized copper has higher emissivity than black pipe. After being in service for a number of years and fairly oxidized the copper will still have lower emissivity than the black pipe. Higher emissivity and larger surface area of the black pipe mean higher loss via radiation as well as convection.

The difference is likely to be slight in the grand scheme of a heating system, but the bare copper will loose less heat. Insulate and the differences disappear as both convection and radiation are now governed by the insulation itself.

Personally I like the strength and permanance of black pipe--especially in the gravity systems on which I work.

Tim_24

Mike