Doesn't matter if done when boiler is running or not.

Check the pressure in the boiler. Should be at least 12 PSIG for a 2 story home. Your boiler may have an auto water feed, or only a manual water feed. You ran out of pressure while bleeding air out. So there is still air in that rad.

When the circulator came on, you heard water moving in the rad because of the air. Get the boiler pressure back up, and continue bleeding.

You have cast iron radiators, cast iron baseboard, and cooper fin baseboard.

 

the boiler has a manual water feed.

should I feed water into the boiler until it has 12 pounds, bleed the cast iron radiators again and then check the water pressure levels in the boiler and make sure it's back up to around 12 when I'm done?

Here is a suggestion for you. I have a similar setup, you have to bleed the air at the start of each heating season, and if you have an air leak into the system, you may need to bleed one or more additional times. The bleed valve is sometimes called a coin valve, because often they are slotted, and can be opened using a dime. I replaced all my manual coin valves with automatic bleed valves, mine were Swiss made, can't remember the name but I got them at a plumbing supply store, cost a few dollars each. These valves will bleed air automatically while water is circulating, maybe when water is not circulating too. In any case, I usually manually bleed the valves at the start of the heating season, but this year there was no air, so I guess they are doing the job.

I typically bleed the radiators each year just as the fall/winter season starts.

I'll look more into the automatic bleed valves.

A few ideas for ya....

Firstly it's not at all uncommon to have to bleed the rads several times to get all the air out, but if you're having to bleed a lot all the time then check your expansion tank and your relief valve. If your relief valve is weak and blowing prematurely then the water it blows off has to get replaced when the system cools. You'll also blow off and replace water at higher intervals if your expansion tank is too full and can't handle the expansion.

This fresh water contains air which comes out of absorption at the lower boiler pressure (as compared to city water pressure) in much the same way as the CO2 comes out of a soft drink when you take the cap off (drop the pressure). So in other words ever time the boiler has to fill with fresh water for what ever reason, you're quite naturally adding air to the system.

The other thing that happens is that the fresh water fill contains dissolved oxygen which decays the metal inside the boiler. One of the byproducts of rotting matter is the generation of gas.... which of course you get to bleed out at a later date.

the only radiators that I have that I'll typically get air out of when I bleed them seems to be the cast iron radiators. if I ever get any air out of my baseboards, it's very little.

 

Here is a suggestion for you. I have a similar setup, you have to bleed the air at the start of each heating season, and if you have an air leak into the system, you may need to bleed one or more additional times. The bleed valve is sometimes called a coin valve, because often they are slotted, and can be opened using a dime. I replaced all my manual coin valves with automatic bleed valves, mine were Swiss made, can't remember the name but I got them at a plumbing supply store, cost a few dollars each. These valves will bleed air automatically while water is circulating, maybe when water is not circulating too. In any case, I usually manually bleed the valves at the start of the heating season, but this year there was no air, so I guess they are doing the job.

 

A few ideas for ya....

Firstly it's not at all uncommon to have to bleed the rads several times to get all the air out, but if you're having to bleed a lot all the time then check your expansion tank and your relief valve. If your relief valve is weak and blowing prematurely then the water it blows off has to get replaced when the system cools. You'll also blow off and replace water at higher intervals if your expansion tank is too full and can't handle the expansion.

This fresh water contains air which comes out of absorption at the lower boiler pressure (as compared to city water pressure) in much the same way as the CO2 comes out of a soft drink when you take the cap off (drop the pressure). So in other words ever time the boiler has to fill with fresh water for what ever reason, you're quite naturally adding air to the system.

The other thing that happens is that the fresh water fill contains dissolved oxygen which decays the metal inside the boiler. One of the byproducts of rotting matter is the generation of gas.... which of course you get to bleed out at a later date.

 

Turning up the heat before bleeding the rad doesn't help anything. On a rad that has no water in it. Running the circ will cause air to be pulled into the piping, and send it to another location.

Since your pressure dropped to 0 so quickly. Good chance you have a steel expansion tank that is almost completely full of water. And needs drained.

 

I do have an expansion tank, yes.

is there anything special that I need to do before draining that tank? Can I just open the valve on the expansion tank and let it go until it's empty? does the boiler need to be off?

 

Boiler off. Isolation valve between boiler and tank closed. Connect garden hose and run it to a drain. Open drain valve, when water stops running out. open vent to let air into tank so the rest of the water drains out.

 

thanks.

I'll have to familiarize myself with the system tonight before messing with the tank.

 

checked the boiler and expansion tank tonight. I only see 2 valves, both on the expansion tank itself. the line going from the expansion tank to the boiler does not have a shut off valve on it.

while I was down near the boiler tonight, I also checked the water psi, and again it was at 0. filled it back up to 12 psi, but I hope this is not something I need to do daily. what could be wrong there?

 

The valve the pipe from the boiler attaches to is your drain and isolation valve all in one. Connect garden hose and run it to a drain. open valve fully. let drain until it stops. Then remove vent cap and let drain again. When done, put vent cap back on. turn valve fully closed. Add water until system pressure back up to 12 PSIG.

You could have a leak. but try draining tank first, and see what happens first.

 

I forgot that I had paid for a service contract with a heating company in my area a few months back that covered parts and labor for my boiler.

it appears that my water psi gauge is bad as the tech hooked up his gauge and it gave a proper reading - slightly below 20 psi, but that was because he added water to the system since my gauge was showing 0. he drained some water from the system so it was at 15 psi.

they have a new gauge on order and will install it once it comes in.

thanks for the help!

 

Your welcome.

 

sigh...ever since my water pressure/temp gauge was replaced last week, my PRV has blown off 3X! The PRV is rated at 30 psi. I happened to be in my basement when it started to blow off on Monday night - the water psi was around 20, so I'm thinking maybe the temp is causing it to blow...?

in the 3 years of me living in my house, I don't recall the PRV ever blowing off once, though the gauge referenced above was probably faulty the entire time.

does the water pressure/temp gauge control when a PRV will blow off?

I had the same company out yesterday that replaced my gauge last week. the tech seemed to indicate that the expansion tank might be a problem. he opened up the drain valve on the expansion tank and the water seemed to shoot out of there like a rocket.

I have one of those old, steel (I believe) expansion tanks (photo is in an earlier post in this thread), probably original to the Weil-McLain boiler that is pushing at least 33 years old - if the maintenance records are correct.

The tech mentioned that the cost to install one of the newer style expansion tanks, plus moving the circulator pump from the return side to the supply side might cost over half as much as just replacing the entire boiler system.

Does anyone have any opinions on what could be done here? I have the company coming out again tomorrow morning, but would like to hear some opinions before then, if possible.

 

Tank probably need drained. The tech may not have completely drained it. And if he didn't, it will continue to blow the relief valve.

A bladder tank can be installed in place of your steel tank. Without having to move the circulator.

 

yeah, I don't think it was entirely drained.

thanks for the comments regarding replacing the expansion tank. I see you're in PA..how far away from the Philly area? :laughing:

 

An hour or so.

 

had the heating company out today.

they drained my entire system, replaced the pressure relief valve and boiler drain valve (this was shot), filled the system back up and then bled every radiator/baseboard in the house until each of them were pushing water out of their bleeder valves.

the tech mentioned that the gate valve that lets water into the system might have a slow leak in it and may need to be replaced if the system keeps acting up. of course that is not covered under my service contract with them....

fingers crossed that everything is fixed up now...

 

You'll find up in a day or 2.