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How much bleeding is too much bleeding? (Hydronics)
tastydonuts
Registered User regular
Registered User regular
My home is a full gut reno and the entirety of the radiator system had to get replaced. The cast irons exploded and/or popped at some point, the ones that survived I didn't want. Thankfully, the boiler survived though it required some minor repairs too. But it's a high efficiency boiler and all, and it works w/o issue. But basically this is the first time these radiators and system have been put to use.
Radiators on the second floor all work fine. Radiators for the vestibule also work fine. The radiators on my first floor, not so much. They are 5', 12" high panel radiators. Runtal brand, should there be some particular nuances about them I'm unaware of.
Bled them directly, and at first I got a lot of sputters and such like the youtubes and folks I've asked said (I had dry heat before this, or good ol' kerosene so these are my first radiators). But they don't heat up. Bled the other radiators (though that didn't have any effect). I've done it both with heat running and not, nothing.
Figured maybe I wasn't doing it long enough, so I opened one up for a few minutes. Doing this I did get some more sputters, and I stopped when I felt warmth on one side of the radiator. Though I believe that was by virtue of the cold water that was in the radiator simply being bled out to the point where it reached the other bit, because it's cold again.
Don't want to call someone in and have them do the same thing, but longer and then I have to pay him and it works, so... yeah. what gives? Do I have to wait for hte whole heater to be hot to consider it bled enough?
Radiators on the second floor all work fine. Radiators for the vestibule also work fine. The radiators on my first floor, not so much. They are 5', 12" high panel radiators. Runtal brand, should there be some particular nuances about them I'm unaware of.
Bled them directly, and at first I got a lot of sputters and such like the youtubes and folks I've asked said (I had dry heat before this, or good ol' kerosene so these are my first radiators). But they don't heat up. Bled the other radiators (though that didn't have any effect). I've done it both with heat running and not, nothing.
Figured maybe I wasn't doing it long enough, so I opened one up for a few minutes. Doing this I did get some more sputters, and I stopped when I felt warmth on one side of the radiator. Though I believe that was by virtue of the cold water that was in the radiator simply being bled out to the point where it reached the other bit, because it's cold again.
Don't want to call someone in and have them do the same thing, but longer and then I have to pay him and it works, so... yeah. what gives? Do I have to wait for hte whole heater to be hot to consider it bled enough?
“I used to draw, hard to admit that I used to draw...”
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closest to the radiator downstairs/upstairs? in theory you need to bleed until the water is flwoing without any air in it. also sounds like your pressure might be too low.
also make sure the boiler is turned on and hot before doing this to make sure its pressurized/pushing water through
Possible problems:
System is not liquid full (keep bleeding)
Not getting enough water flow (blockage in line or possibly radiator itself)
You have no insulation of lines feeding the problem radiators (I doubt the water is losing enough heat for this to be the case, but it is possible depending how much exposed pipe there is and how cold it is)
The pipes in the basement aren't insulated, but the second floor radiators are getting hot water w/o cold spots on them? Wouldn't the furthest ones be cold? Though, if I go through and check the pipes the ones that to two of the first floor radiators do feel cool before going upstairs into those radiators? Weather's been in the 40s to 50s too, don't think that's cold enough to make it not work?
As for flow, I did have to one of the circulator pumps completely replaced too, as it was ruined and was popping fuses on the board. Basically the majority of the pipes (and radiators) exploded at one point due to major cold snap a few years back before I bought the place. There is a second circulator pump, but I was told by my plumber that it was okay and I wouldn't need need to replace it.
When I bleed the radiators only clear water comes out.
There should be a pressure gauge somewhere which tells you the pressure inside the pipes.
This should also have indicators that tell you if it's to high or to low. If you really can't get it fixed you should get a plumber to look at it.
There's a combo temp/pressure gauge on the boiler itself. It doesn't have the indicators you're talking about. The PSI looked like it was 12, which is the required operating pressure according to the manual. It is entirely possible imo that the gauge is broken given what happened with the old piping and all. Plumber said it didn't need to be replaced, and it should be okay... it does move. But yeah, I guess I'll have to bring him in. Maybe there's like something he can hook up to determine the pressure in the system or whatever too.
But uh, there are two large pipes that run the length of the house in the basement and I *think* each radiator on the first floor is connected to both. They're from the original configuration, the rest is all new copper, and this is the first winter that any of it's been run. My assumption is one is "outbound" and one is returning, or whatever the appropriate terms are. But, I... don't think there's anything in the system to clog stuff. One of the pipes that goes into the radiators is cool period. I'm guessing that's the one that supposed to be cooler because it's going back to the boiler having run through the radiator.
One pipe on two of the radiator is hot at the point where they are connected to the large pipe, but cool down before they actually even leave the basement. The rate of cooling seems to be pretty high (like, within 2 feet)? The rear radiator on the first floor has one cool pipe too, coming out the end with the bleeder so I'm guessing it's the return pipe, but as it's at the end of the large basement pipes and the pipes that go up to the second floor radiator(s) are very close to them, It's hard to say if they're hot in the basement because they are hot, or just because of where they're situated.
if there are 2 pipes on the radiator - it's 2 pipe, which means you generally push hot water through it (assuming not still steam). 1 pipe is steam-only, as the steam heats it up, then drips back down as it cools and condenses.
If one pipe is cold and one is hot, you're likely airbound or clogged in some way as your return should still be at 100+ degrees.
Supply valve is closed because when the original gut-project plumber did the pipes they didn't put another automatic fill valve on the system. It does have a LWCO thing, and it is functional (was one of the first things my current plumber checked). I opened it briefly to replace what I had removed from the bleeding, but it's otherwise shut. I do want to get an automatic fill valve installed again, though the impression I got in talking about it was that it's kind of redundant.
Schuss:
Yep, it's hot water. And this is probably something that I'm going to have to have them come back and look at then? There anything specific I can say to point it away from my not just needing to bleed them (more)?
Show them the pipes being cold on one side and hot on the other. In one visit they should be able to bleed it to the point where you can feel the return getting warm.
Per their recommendation, they split the loop so each radiator returned on its own. This and some more bleeding of the individual units and they started to work properly. Joint was leaking on the rearmost one, so they replaced that, but it's still got some kind of blockage or something as it's cooler than the others even after all that.
I do have to say that ProPress tool is pretty neat.