No heat from bedroom 'radiator'

fotostatJanuary 16, 2009

Hello, I live in a condo built in the early 60's, I believe the heat is hot water.

I have 7 "radiators" around the condo, they aren't standard radiators, they are indented into the walls and only contain a small pipe with fins on it. I posted a picture below of the inside of the bathroom radiator, all the others are the same except they are much wider.

Last year at the beginning of the Winter I bled all the air out of all the radiators by simply removing the cap from the tire stem type fitting on the top right hand corner (see picture) and turning the valve below it. I let the air out and closed the valve as soon as water started coming out, this was enought to give me heat all Winter. I keep most of the radiators turned off (valve in lower left hand corner) because I like it cool and I get a lot of heat from the unit underneath me. I usually only turn them on when it's real cold.

Fast forward to this year, I go around and bleed all the air out of the radiators around the beginning of December. They all work except for the bedroom. I go back a week later to try and bleed more air out, yet only water comes out.

A month or so later at the beginning of this week I try again, this time using a tube so I can drain some water out too without it going all over the place. When I open the valve I get a shot glass of water out then a lot of air. As soon as this air is out the radiator works well, it gets my bedroom to 74 degrees while it's 28 degrees outside, WAY too hot for me, so I shut that radiator off.

Two days later it's down to 12 degrees outside and I want some heat in the bedroom, so I turn the radiator on. This time no heat at all, ice cold. I open it up (big pain to get the metal cover off) and try to bleed it again, this time a lot of air came out yet it's still cold, no heat at all. I continue to bleed it but only cold water comes out.

So what could be the problem? I'd think it was something outside of my unit, but I was able to fix it the other day just by bleeding it, yet when I bled it before that it didn't work. It seems like there is still air stuck in it. Any advice?

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It looks like there's a valve under your auto vent. It needs to stay "on". This auto vent should automatically bleed the air out of the system, when the water gets to it, the ball in there will seat and stop the flow.

It may need to be replaced.

    Bookmark   January 18, 2009 at 11:03AM
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Hey wirenut, thanks for the reply!

The valve under the autovent on each one of my radiators were all turned off. Afer removing the cap from the top of the autovent I open that valve underneath it to let all the air out manually. I was told that these autovents tend to leak after old age and that's why the valves underneath them are closed in my condo.

Since I manually bleed each radiator by hand, and air/water comes out, I should be getting heat from that bedroom radiator, correct?

Would replacing the autovent make any difference? I could see replacing it if nothing came out, but since it seems to allow the air and water to flow thru it when I bleed the radiator.

    Bookmark   January 18, 2009 at 1:54PM
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Any help?

Again tooday I bled it and let more air out as well as about 2 gallons of water. The radiator got hot just because I got some hot water into it, but within 15 minutes it was cool again.

    Bookmark   January 20, 2009 at 8:45PM
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What floor are you on? Air rises to the higher radiators in the system, so air may be getting in at a lower floor.

    Bookmark   January 21, 2009 at 1:42PM
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I'm on the second floor of a two story building.

I could understand that air will collect in my radiators more than the ones on the lower level.

However, all my other radiators work fine (I bleed them once a year). THe radiator in my bedroom isn't working at all now, even right after bleeding the air out.

It seems as if air is stuck in there somewhere.

Just to recap, the bedroom radiator didn't work at all when I first bled it, nor did it work the second or third time I bled it. Then on the 4th time that I bled it it worked VERY well (super warm, I had to shut it off). A week later when i turned it back on it did not get hot, since then I have bled it 4-5 times, air always comes out but apparently not enough to allow the hot water to flow thru it.

    Bookmark   January 21, 2009 at 5:08PM
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    Bookmark   January 23, 2009 at 1:30PM
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The rad appears to be off level and the air could be handing in the left side. Also you could have other pipes in that loop that collect air at the elbows or your system pressure could be low.

Try elevating the rad on the air vent side and see what happens.

    Bookmark   January 24, 2009 at 11:46AM
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When you bleed the radiator are you shutting off the valve on the return? If not you're not bleeding properly, for all you know you could just be pushing the air out of the radiator through the return but then air in the supply line ends up in your radiator again. You shouldn't have to bleed that system over and over. The isolation valve under the auto vent should stay open and the cap on the stem should remain loose all the time. If any vents leak water they're probably water logged and should be replaced. You also don't know what kind of pressure your dealing with in the heating system either. It could be to low and affecting hot water flow. Are you responsible for any maintenance on the boiler? Also, if your condo is overheating your have another situation to deal with also. Circ pump running constanly because of a faulty relay, a bad flow check, t stat out of calibration, on and on and on. It all depends on what kind of installation you have in there. It sounds like your system needs more attention then what you are trying to do.

    Bookmark   January 24, 2009 at 12:26PM
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Thanks for the replies!

baymee, the radiator in the picture is the one in the bathroom which works VERY well. The one in the bedroom is giving me the problem and it is level.

Mr Havac, I've bled the radiator both with the valve opened and closed.

I don't know what temperature you would consider as "overheating". With all the radiators opened it will be around 73-75 degrees in here on the second floor, probably 3-5 degrees cooler on the first floor (no insulation between floors, old building). There are a lot of old people in my condo so I assume they want to keep it warm.

Out of all the things you mentioned, why would just one radiator not work? All the others work perfectly fine. None of them have the isolation valve left opened, I just bleed them once a year. My next project in the Spring will be replacing the auto vents so I don't have to worry about bleeding them, but for now I would just like to get the bedroom radiator working.
Things such as "a faulty relay, a bad flow check, t stat out of calibration" would effect just one radiator in one unit of the entire building?

I am not responsible for any maintenance of the boiler. I am on the board of directors of the condo association and brought this problem up at our last meeting. All the other board members agreed that thair heat is working fine and the problem is with my one radiator, which is my responsibility.

    Bookmark   January 24, 2009 at 2:36PM
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Ditto on havac's last sentence

Constant air being bled leads me to believe air is being introduced into system due to faulty install/piping, too low of cold fill water pressure, circulators drawing air in through poorly placed vents, or system leaks requiring more than normal make-up water.

Having auto vents on your convector's is a sign that someone has been adding band aids versus fixing/correcting the problem. On a proper system, there is no need for any vents with perhaps a few manual vents at high points to add convenience and shorten bleed process after a drain and fill. The manual petcocks below were used to isolate the auto vents for change outs but more importantly, those $5 vents can not be trusted and tend to lime up and leak, resulting in building damage. Look at the convector header, there is already signs of that happening. If the floors were wood, and it leaked without knowledge for as little as a few days, damage is done, not to mention the ceiling below and the mold issue.

My thoughts are auto vents belong in basements where damage won't be incurred. Proper piping with a correctly placed and sized air eliminator in the basement/mech room, along with proper operating pressure, appropriate circulation and expansion tank and this wouldn't be happening.

Sorry fotostat, I for one never saw this post

    Bookmark   January 24, 2009 at 2:43PM
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When I go into the basement I could see how the heating is piped into the first floor units. Basically there is a pipe (about 1 1/2") running the length of the building with two small pipes branching out of of the top of this main line and up into each radiator.

Knowing this, wouldn't each radiator need a way to bleed the air out of it? If you only had a few manual vents at high points, how would you get the air out of each radiator? This most likely doesn't have to do with the thread topic, but I am curious and like to learn (I'm an electrician and enjoy all mechanical issues).

zl700, you are absolutely right about the leaking water. There is hardwoof flooring in these units and I have white carpet on top of that. I was told to leave the auto vent valve closed because water will leak and ruin the carpet and flooring.

    Bookmark   January 24, 2009 at 3:19PM
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Sounds like you have a standard 2-pipe system, where the water flow and highest flow rates are at the closest convector to the boiler/circ. In this case your closest convector's to the pump must be closed down partially to allow more flow to the ones downstream. Start with the farthest wide open and start closing others working back toward first. This of course will only work if you have a circ capable of the flow rates with the head/friction needed. And of course as stated earlier, if proper pressure is not there,or air continues to be introduced your fighting a losing battle.

I'm a huge fan of 2-pipe reverse return, but installers either don't understand or due to added cost don't install that way. (This is when the first rad/conv is the last on the return thus the first on the return is the last on the supply) 2-pipe reverse returns self balance flow among circuit regardless of individual rad/conv valve settings.

Good luck

    Bookmark   January 24, 2009 at 5:35PM
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I took another stab at it tonight. I bled the radiator, a lot of air came out, then water, then a mixture of air and water, then just hot water.

I gave it a few minutes and the radiator is hot so it's working and I'll have heat tonight!

The only question is whether it's going to continue working like it did after I bled it last year, or if it's going to continue to get a massive amount of air.

    Bookmark   January 24, 2009 at 10:08PM
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Somebody should look into why you are getting air in the system. Oxygen in the water will ruin the boiler eventually and a good sealed system will never get air into it.

    Bookmark   January 25, 2009 at 6:24AM
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Check the valve maybe it broke, when you bleed your bleeding from the return side and the hot side remains closed. the radiator heats up and then turn cold.

    Bookmark   January 25, 2009 at 4:24PM
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