HALP!!! I recently drained and refilled my hot water baseboard system. Today I turned on the heat and made sure all the radiators and panels were clear of air....and they are (except for one, maybe). Note: these are not fin tube baseboard heater...they are radiant panels. I have one baseboard heater that I cannot get to heat up. I've bled it over and over again and still get no flow through it. I get water out of the bleeder but it is hisses. Usually it hisses until the air is clear, then goes quiet. When I'm bleeding it, the top of the baseboard heats up but the bottom remains cold. I don't hear any "glug, glug" sound when I bleed it. Usually when there's air in the system the bottom of the baseboard will heat up and the air pocket stuck at the top stays cooler...this is the opposite. The system is at full pressure. There are no valves to isolate this and force water through it. I'm not sure what the layout is called, but the heaters are not in series...they are in parallel. There is one main loop that goes around the perimeter of the house, then each panel ties off of and back into the same leg of the loop. The fittings used to tie into the loop are supposed to direct the flow into the panel. I had no issues with this last year. I have a hard time believing there is an air pocket stuck at the bottom of the panel, but maybe there is. Any ideas?
From my brother, a former hydronic engineer... “.... pumps pump water they do not pump air. They will not purge air from the baseboard, it either has to be purged back at the boiler by a drain and QuickFill or a garden hose but if you don’t have enough pump pressure and flow, air will come out of solution and hang out at the high point and reduced flow through those baseboards because the air will displace water through one or more...And if air continues every year to get stuck in that particular baseboard raise the pressure in the system and install a bigger pump or move the pump so that it’s pumping away from the expansion tank on the discharge of the boiler- it’s usually one or the other, often both....”
I don't know what to think here. I disconnected the supply and return line and can blow air through so I know it isn't blocked. It will fill up with water, air bleeds out, but won't circulate. I think that monoflow tee isn't directing flow like it should....but it worked fine last year.
Yeah, that is truly weird. Maybe try a bigger pump as I've seen that to work IME, EVW's brother would be correct. Also as CBVT said, those bleeders can suck air in. I'ma firm believer, as my dad taught me, that any hydronic heating system should have a very good air scoop on them to prevent issues like this from happening. I have had good personal experience with Taco's air scoops. Is the air vent on your panel the schrader style? Can you fit a tube the size of an aquarium airline hose, down it it? If you can, try that with either a mityvac, or any other way of creating a vacuum. Try this at varying depths. Hopefully you can find the offending air and evacuate it.
Yep, guarantee there is air in there somewhere...a system that won't bleed completely will make you old before your time...BTDT. And these situations can be really tough to "armchair quarterback" too...
I have been whiskey thinking on this for a while this evening and have a few ideas. Just need to get a few fittings tomorrow.
It was air. Not sure why the bleeder on the panel didn't do its job, but I added some ball valves on the return and made a new purge line. Flowing like it should now.
When I had troubles with constantly having to bleed radiators I found the expansion tank had a leak. It never dripped until it got really bad, it just got waterlogged and quit working. I kept finding the air gone in the expansion tank. It was an old style with no bladder. Replaced it and haven't had to bleed a radiator ever again. It must have been rusty and very slow leaking for a while because it had been an annual September event until it suddenly became a weekly event.
This is what my dad taught me to do . Isolate each end with a shutoff , I use ball valves and put a ball valve boiler drain inside the the ball isolation valves. Hook up a supply hose and drain hose then using house pressure fill the zone with water. Also good way to remove water from a zone or hot water heater. First isolate with ball valves then blow air in the supply valve and let it force water out the return. Long hose will go thru window to drain outside.
