Pair of rads that won't bleed

Old 10-16-06, 03:26 PM
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Pair of rads that won't bleed

Just found this site -- looks like fun.

We have a hot water system. I've bled the air out of all but 2 rads on the upper floor. The last 2 blow air for about 4 seconds and then stop. From what I can see they look to be linked and on the last loop before the system returns to the boiler.
Is this what you call an air lock?
Could there just not be enough pressure in the system to push the water that far? There are 11 rads around the house and the gauge shows 14 psi. The make is AO Smith, "Copper" and is probably 25 years old.

Thanks for your time and help.
Old 10-16-06, 07:04 PM
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2 rads

Try increasing the pressure to about 18#. you might be a bit low.
Old 10-17-06, 09:39 PM
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14 PSI is good for about 30 feet of elevation, excluding pressure drop across elbows and other fittings. You did not state how many floors you are trying to heat, but an increase in pressure would be a good starting point.

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