These bleedin’ radiators!
December 15, 2020 6:51 AM   Subscribe

How to troubleshoot my hot and cold radiator situation in chilly Minnesota?

It’s winter in Minnesotan. Mild so far, but we’re not out of the woods yet. My partner and I live above an office (the rental company for our apartment and a bunch of others in the area). We’re the only tenants in this building.

We have a total of 8 radiators in our apartment, all of which can be bled with a key. Most of them have on-off knobs at the bottom, and all are in the ‘on’ position. We control the temp with a thermostat in the living room. We don’t pay a heating bill; the rental company covers it for the whole building. Our building was built around 1917, so we have oooold radiators.

My initial concern, early this winter, was that the radiator in my office was always cold as ice. The other issue was lots of gurgling in the bedroom radiator. I went around and bled all the radiators (starting furthest from where I assume the boiler is, and moving toward it).

All radiators hissed and let out steam, and water gushed out of only one before I closed it back up. Since then, things have been not right. I’ve tried bleeding everything again, but maybe I’m making it worse.

My office radiator is still ice cold, and now most of the radiators in the apartment are as well (including the bedroom). The bathroom and living room radiators, at either end of the space however, are popping off— super warm and sometimes gurgly. Those two are keeping the whole place warm at this point.

To be clear, this isn’t an emergency heat situation (yet). I think the recorded temp in the bedroom the other night was around 63° F, which is chilly but we have lots of blankets. And the bathroom is a cozy dream to pee in. I’d just love for things to be heating more efficiently and evenly than they are now.

We have the option of submitting a request to the rental company downstairs. We try to only ask for things we really need, and so far they’ve been fairly accommodating and quick. But they are NOT wearing masks in the office downstairs, and I’d really rather not have anyone come into our place unless absolutely necessary. Is there anything I can ask them to do that wouldn’t involve them coming into our place? I have no idea if they’ve bled the radiators in their office downstairs. I read that it’s best to bleed the first floor first and then move up?

Thanks for your help!
posted by sucre to Home & Garden (16 answers total) 1 user marked this as a favorite
 
Hot water radiators need to be bled COMPLETELY. Until water comes out. Otherwise you still have air displacing the hot water you want to be in the radiator.

It is possible that some of your valves have collapsed internally, but in that case, you'd get no air, steam or water out of the bleeder.
posted by notsnot at 7:42 AM on December 15, 2020 [1 favorite]


I also vote for bleeding them again. And talk to the office downstairs, just ask if they are having the same problem and if they’ve bled their radiators recently. If their heat is fine and bleeding yours again doesn’t help, it is time to call in a maintenance person.
posted by mai at 7:45 AM on December 15, 2020


I am a fellow radiator using Minnesotan and in this instance it sounds like you might need to contact whoever has access to the furnace/boiler and have them check its pressure. The pressure may be too low right now for it to get hot water circulated to all the radiators, but if that’s the case it is often a simple fix by adding some more water to the boiler - or at least it is at my house. This is what I usually do when I notice the upstairs radiators are struggling to heat up but the downstairs ones are mostly fine. (I am not an expert, though, and have a halfassed understanding of radiator systems at best.)
posted by castlebravo at 7:46 AM on December 15, 2020 [1 favorite]


Yup - water should come out, or else there's still air in the system. Grab a towel and wrap it around the valve before you use the key - should be enough for most drips. Good luck!
posted by sedimentary_deer at 9:07 AM on December 15, 2020


Seconding the point that a hot water heating system should have no air at all in it - you need to bleed out all of the air. Unfortunately, when you do this, you depressurise the system, and no more air comes out. So, as castlebravo suggests, the system will usually need to be re-pressurised (adding more water to the system to make up for the air you've let out. Then you can continue to bleed out the remaining air. Sometimes you'll need to re-pressurise and bleed two or three times before the system is air-free and back up to a pressure where the heating works correctly.
posted by pipeski at 9:10 AM on December 15, 2020 [1 favorite]


Could you clarify---Hot water or steam??
posted by H21 at 9:20 AM on December 15, 2020


Yes to bleeding the radiators till an even stream of water comes out. Yes to checking the pressure.

If the top of the radiator is cold but the rest is hot, the problem is likely air.

If the bottom/middle of the radiator is warm but the top is hot, the problem is likely sludge.

Sludge builds up in your system when corrosion occurs, often due to long-term exposure to air in the system (which is why radiators need to be bled).

Signs of sludge include:

-- Black, grey or brown water coming out when you bleed the radiators
-- similar off-colour water coming out of the taps the first day you turn the heating on

Getting rid of sludge is one day's work with a plumber or (more likely) two. They turn off the main water supply valve, drain the system, flush acids through it to remove rust and break up the sludge, and take off and physically flush out any blocked radiators.

If you're adventurous, there's a DIY guide here and a how-to video here. It is, at minimum, a two person job. If you haven't done this before, do not attempt it alone and consider hiring a professional. You could burn yourself badly and/or flood your floor. Sludge stains don't come out of carpet. Ask me how I know.

The good news is that after this is done, the radiators work better and are MUCH warmer. Best of luck!
posted by Pallas Athena at 10:10 AM on December 15, 2020 [1 favorite]


I'm puzzled by what the people talking about needing to add more water to the system are on about. Normal hot water radiator systems have an automatic feed valve near the boiler
connected to the potable water supply in the house. The feed valve has a double check valve to prevent radiator water from backflowing in to the potable system and a pressure regulator to maintain a set pressure in the system, typically 12psi cold or a little higher in multi story buildings. As you let air or water out of a radiator through a bleed valve, the feed valve will top off the system as needed. Just open the bleed valves and wait till water comes out. N.B. my comments relate to typical North American hot water heat. I understand that European systems may be more strict about interconnecting potable and boiler water. Also note that If the feed valve is broken, the auto top up may not happen.
posted by Larry David Syndrome at 11:28 AM on December 15, 2020


Not all hot water radiator systems have automatic feed valves. Source: my hot water radiator system (North American).
posted by ewok_academy at 12:25 PM on December 15, 2020


Mine doesn’t have automatic feed either (UK) - I need to open a tap underneath the boiler to refill if it’s under pressure. So I’m nthing to bleed again, and ask the downstairs people to increase water pressure if needed.
posted by rd45 at 12:46 PM on December 15, 2020 [1 favorite]


In addition to the knob at the bottom which is either on or off, does it have any kind of vent up on the side of it? If it does, does it have any kind of extremely easy to miss slider like on the bottom of this picture? We used to live in an apartment with radiators and had the opposite problem that one room was always super hot. It turns out that we needed to keep all the knobs at the bottom open and control the heat to each room with the little vent slider.

https://www.supplyhouse.com/Varivalve-VASA-Varivalve-Adjustable-Straight-Valve-3841000-p?gclid=Cj0KCQiA2uH-BRCCARIsAEeef3ljdfES9-iIfusjlDluCkYmPVDx7VHinnXKVFS1OcCShiFNESnehhgaAhZPEALw_wcB


If your radiators don’t have these, maybe you can see about having them installed? They’re like $20 apiece.
posted by cali59 at 12:55 PM on December 15, 2020 [2 favorites]


Response by poster: Thank you all so much! I BELIEVE it’s a hot water system, because we have two pipes per radiator, but I actually don’t know. Here are two photos.

I just went ahead and bled all 8 again. Most give off a few seconds of hiss, and then... silence. I left each one open for several minutes. No drips, no sound, no water at all. Ice cold (no warm spots) and completely silent after the initial short hiss.

I think it’s time to check in with the folks downstairs. Thanks so much to everyone who offered suggestions!
posted by sucre at 2:11 PM on December 15, 2020


In Minnesota you are very likely to have a hot water system.
posted by mai at 4:13 PM on December 15, 2020


All radiators hissed and let out steam, and water gushed out of only one before I closed it back up.

If only steam or hot air came out, then you still have air trapped in your radiators. Try bleeding again until water runs out the bleeder. It doesn't have to gush, but it shouldn't bubble with air. Use gloves and hold a rag under the bleed to catch water.

Most people recommend bleeding when the water pump is off, but you might try it both ways. The aim is to get all the air out and water all the way to the top.
posted by JackFlash at 4:42 PM on December 15, 2020


Response by poster: UPDATE! I put in a service request this afternoon. Maintenance guy just called to say he’d gone down to the boiler and found that it had super low pressure, and that he’d refilled it. I can already feel the radiators heating up, even the ice cold baby in my office. So happy. Thanks again, everyone!
posted by sucre at 5:09 PM on December 15, 2020 [7 favorites]


It might be a good idea to bleed your radiators again. If there was low pressure, air might have entered the radiators. You should bleed them until there is no more air and only water comes out.
posted by JackFlash at 8:41 PM on December 15, 2020 [2 favorites]


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