I know enough to get me in trouble...

Old 03-23-06, 10:17 AM
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I know enough to get me in trouble...

I know a little, and just the right amount to get me in trouble. I have a Hydronic FHW system. I need to remove a baseboard heating element. So, I drained the zone down and shut off the furnace. I cut out the baseboard and connected the cut ends together to complete the loop. I then let water back into the furnace and attempted to get all the air out. When no air was coming out, I figured complete. The pipe for that zone gets hot next to the furnace, but no hot water is making it to the other heaters now. I suppose I should have followed the hot pipe as far as I could to find where it turned cold? Maybe I didn't purge correctly?

The other zones are still operating just fine.

Next question, I've seen posts that state this type of system needs only 15 psi to operate, but when I look at the dial there is a marker at 50psi, is that possible? I'm not blowing the PRV, so I don't think it's "too much" but maybe not supposed to have that much?

Thanks in advance,
Old 03-23-06, 05:06 PM
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First check the gauge to be sure it is not calibrated in "feet" rather than psi.
If you have zone valves, you must have the zone valve open in order to purge the air. Some pics of the boier & nearby piping would help. You can host them on photobucket, yahoo, or a similar site & provide a link here.
Old 03-24-06, 06:09 PM
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I suspect that Grady is correct and the gauge is calibrated in feet and not psi. Oftentimes the gauge will be titled "Altitude" and have a second (smaller) scale graduated in psi.

I would need to know more of how this is piped to offer much help. If the removed baseboard is in a series loop then it is most likely an air blockage. Try to bleed the air from all the other units on this loop with the zone valve manually opened. You may have to bleed a fair amount of water from each heater until you get the air bubble(s) moved to the vent.

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