another cast iron radiator question

[Joe]

I've got a seperate loop of my wood boiler system that goes to a little used upstairs bedroom. It has a shut off where it branches off the main line to the house. It has always worked fine, and I just just bled it last week until water came out the bleeder. Now I cant get any water out (I can hear air) , and I can hear the water (or air bubbles) gurgling around in the radiator and pipes. I've tried bleeding it with the main line to the house closed off to increase pressure going to this bedroom loop, but nothing works. Its very strange, since it just worked last week. It is getting some water, as parts of the radiator are getting hot. Sometimes it sounds like the water is actually going down when I open the bleeder instead of up. I have noticed a suction on the bleeder screw at times though most of the time air definitely comes out. My boiler is full.

I heard similar sounds when I was running the boiler pump off an inverter once during a power outage, and the pump couldnt run full bore. BUt my pump is working fine in the rest of the house (fine as it ever does).

[hallerb]

bad valve?

[Vic Smith]

If the radiator is the highest in your system and you had it filled before, you lost water or had air in the system elsewhere. Loss of water could be from a leak, a relief valve popping, or more rarely an expansion tank taking on water. If you had air trapped it worked its way to the top. My last system had a constant feed from city water through a regulator. Some you have to open a feed valve. If you're sure you're not leaking water anywhere you have to open the feed valve when you bleed radiators. The radiator will fill. Start at the lowest radiator and work your way up. Bleed each until no sputtering and you have a solid stream from the bleeders. If there's anything about your system that runs contrary to what I said, follow the manufacturer's advice (-:

--Vic

[Joe]

Yes its the highest.

OK there are two valves in the loop having the problem. One is a ball valve at the very beginning of the loop, the loop is about 30 feet total (10 feet over and 5 feet up, times 2). There is another, very old valve attached to the radiator itself. That valve has always leaked slightly, on occasion. So air can get in there, but its always been able to and I've always been able to bleed it. I'm guessing its part of the problem though I dont understand why the level wont come up when it did a week ago. the valve leaked then too

I dont know what a feed valve is, and I dont think I have one.

[Vic Smith]

It's a fill valve. How you get water into the boiler. If city water pressure is higher than what the boiler manufacturer wants, they supply a regulator between the city supply pipe and the boiler to lower the pressure. That's my experience, and I've had regulated and unregulated in the same city, so it's a boiler design issue. I don't know anything about well water supplies. Except for the leaker, which you should get fixed, if the valves are open you should have no problem. If the leak is at the valve stem it just needs new packing, but you'd have to lower the system water to below the valve. A typical radiator holds some gallons of water, and I assume the leak from the valve won't empty the radiator in the time span you're talking about, but only you know that. That's the trouble dealing with incomplete information. I don't know if the valve is dripping constantly, or just shed a drop or two when you open or close it. Think you said it was a new boiler, so chances are the radiators were never bled properly by the installers. And since you can't get water out of the top radiator, your fill valve isn't opened, which means you probably don't have a regulator. Just a valve from your water source to the boiler, the same source that supplies your sinks and tub. If that valve is open the water will fill the entire system if bled as I said. Can't be otherwise in my experience.

--Vic

[Joe]

Thats not a problem. ;-) It is a stem leak and its at the very top of the system. Strangely though, when I went back and tried it I successfully bled the radiator. I only opened the ball valve a crack, and that seemed to work better than opening it full. or some other random event is taking place that I dont understand. Anyway its working for the moment. Problem is I will probably have to do this every time I heat the room, which is only s afew nights per week.

Its a slow, steady drip.

No, I've bled the radiators many times since I got the boiler. My boiler only gets filled when I take the hose out and fill it manually. Its not hooked up to my water lines and there's no regulator like my old pressurized boiler had.

[buffalobill]

buffalo ny: in my three story building, the fresh water feeder must be open, the circulating pump must be on, and the burner must be on for there to be sufficient pressure for the water to reach the top floor to allow the air to be bled out.

[Tony Miklos]

What is the water pressure in the boiler? Sounds like it is low, or even zero if the bleeder sucked air into it. Is this hot water or steam?

[Joe]

:

te:

There is no pressure gauge, its a vented hot water system. And to answer previous comments its a self contained private residential system, not municipal.

[bud--]

Vented? Meaning there is a tank at or above the highest radiator and the tank has an open top? If that is what you have the tank water level has to be above the highest radiator.

Other wise there should be a tank that has an air cushion. As water and the pipe expand at different rates the water has to have somewhere to go. I goes into the tank and compresses the air. The other thing this tank does is pressurize the system. The compressed air maintains the pressure. If the tank doesn't have a diaphragm to separate the air and water the air can dissolve into the water and the air cushion disappears. Then you close the valve from the system to the tank and drain the tank. This is similar to a well system. The open top tank does the same thing.

If you don't have an open tank above the top radiator there should be a pressure gauge. You fill the system to a pressure at least 1/2 psi for each vertical foot from the gauge to the highest point in the system.

If the water (not bleed) valve at the radiator is leaking it should never let air in. The pressure should always be positive so water would leak out.

-- bud--

[Joe]

The boiler has a vent/filler tube on top, with a rain cover. It passes air freely.

Sorry, this type of system doesnt have that kind of thing.

Nope, nope, nope.

You would think so.

[Tony Miklos]

Where is the boiler? On the roof? Higher than the highest radiator?

[Joe]

Outside in the yard. Lower than the lowest radiator.

[Tony Miklos]

Well no fricken wonder the vent sucked air in. Better call the place that installed it.

[bud--]

I don't see how the system will stay reliable. Most of the system operates under a vacuum. I expect that over time you will accumulate air in the radiators. You can't bleed any radiators (air will go in).

[Vic Smith]

I'm done giving standard radiator advice to Joe, because I have no experience with this type system. When he said he filled the "boiler" with a hose through a hole in the top I said "Whoa." Joe, you have to go to the company who put this boiler in to get any good advice. It's probably a one-off system too. Good luck.

--Vic

[Joe]

never seen one of these before?

Mine is one off, among 10's of thousands of others much like it.

[Vic Smith]

Nope, never saw one. Real pretty.

--Vic

[Tony Miklos]

I've seen them advertised, and one place nearby has one sitting on a trailer to advertise it. That's all fine and dandy, the one I looked at was a *normal* pressurized system. Why your system isn't pressurized is the really strange thing. Like I said before, get the guy who installed it to work on it. Only way I see of maybe making it work is to use a pump instead of a circulator.