Hot Water Rads *Baseboard*

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Dunbar Plumbing

Master Plumber
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Northern Kentucky/Greater Cincinnati Area
I got out of my league tonight doing a emergency service call fixing a couple baseboard rads. Copper pipe with the aluminum fins.

Pretty straight forward but,

I didn't want to drain it completely down so 1 of the 2 I did, I just capped and interrupted the zone. The other one I reconnected, worked fine when I reinstalled.

They both froze and burst and I normally don't mess with anything related to HVAC but someone offering you $400 to solder two copper pipes....well, you do it.

Since I deal with hydronics on a regular basis, can anyone tell me if when I purged the union leading to the thermal expansion tank was necessary for this system that lost water considerably? I heard the system take on a great deal of makeup water initially when I turned it back on, which was good but my concern even now is I hope I didn't trap air in those lines.

No bleeders at the baseboard rads. Where I did bleed it was at the boiler, the lowest not highest part of the system. We can't confirm that "some" of the zones were down before this freeze happened or not. (woman that lives there has dimentia)

I'm just thinking compressed air in those lines with high heat can pose a danger. Didn't get much when I purged....made sure the bill notated that they need a HVAC tech pronto to reconnect the now dead zone and check the rest of non-working ones to see what is causing the lack of circulation in them.

Anyone know what the primary cause for those baseboard rads to stop functioning? I made up a reason that maybe the 90's that turn into them clog.......? <<< I'm thinking I stretched the truth.....but those rads are just a straight run of copper.

Any advice appreciated. The majority of rads were heating when I left at 3am though....which the homeowner loved. Couldn't get ANY HVAC guys out tonight and he caught me as the 10th plumber down willing to go to war to do battle.
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Retired Defense Industry Engineer xxx
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New England
To save on running costs, many of the circulator pumps installed don't have enough head to pump the lines full of water if there is air blocking them. If they are full of water, they'll move the water fine. To get the air out of my highest loop, I had to improvise a means of temproarily supplying higher pressrue water. Sometimes, you can open one of the drain lines, and manually open the makeup feed line (isolate the expansion tank to prevent damaging it first) to get more flow under pressure to help purge the lines. My only practical experience with this is on my own system, so can't say the best way to do it.
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