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Is radiator pitch important for hot water boilers?

Hi all--

Dumb homeowner Q here...

I have a cast iron column radiator that tends to get air stuck in it.

I notice it is pitched AWAY from piping (both return and supply are on the same side of the rad, and it slopes away from those).

IS this a problem? I know in my time living with a steam boiler slope was very important.

A little info from my mediocre knowledge base:

System is newer boiler, one zone--converted from gravity to forced.

I know the "airy" radiator was replaced at some point due to freeze...also that room has a sloped floor (oooold house)
but it would be easy enough to shim the radiator if it would help.

thanks very much for any advice!


  • Brad White
    Brad White Member Posts: 2,398
    So long as

    there is a vent at or near the top (within an inch, usually) and the air can get to it, you will be OK.

    Steam has the added challenge of having to get the condensate back out the same way it got in. Air goes up in water, you just need to let it out.

    A little pocket of water on the top is generally not an issue. Sure, you lose a little wetted surface and fractional capacity (academic, really) but the velocities are so low, no sound occurs. Mine have that, no problem.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
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