Steam radiator hot on top and cold along the bottom

maybeitssteve

There's a radiator in my building that isn't heating up all the way. The pipe running to it is getting steam, but only the top and edge closest to the pipe get hot. The bottom along the rest of the length of the radiator stays cool. I think the radiator is one that could be used on a one-pipe or two-pipe system (it's on a one-pipe system at the moment). I noticed that the air vent is at the very top of the radiator (as opposed to being halfway down the height of the radiator). I have a feeling that steam is running up the one side and then along the top of the radiator, thereby reaching the vent on the other side before the cold air at the bottom is forced out. So it seems like the steam is cutting off the vent too early and trapping in the air at the bottom of the radiator. Is that a plausible hypothesis? Would the solution be to install the vent lower on the side of the radiator so the lower air has a chance to escape? I see what looks like a screw at about the 2/3rds of the way down that's painted over. Would that be where the vent is supposed to be installed?

Thanks so much for any help you can give!

Danny Scully

You are correct @maybeitssteve, it’s suppose to be in the lower tapping. Usually that old plug doesn’t come out so easily, so I just drill/tap right above it.

ethicalpaul

Also the vent might be too fast. But slowing it down may have effects on your radiator balancing

Hap_Hazzard

Or the radiator could be set up for hot water.

ChicagoCooperator

But is it heating the room OK?

maybeitssteve

@ChicagoCooperator No, it's not. Problem is other units are heating up faster and staying warm longer, so I either put thermostat in the cold apartment and everyone else gets baked, or a put it in a warm apartment and the one gets cold. I'd rather the cold one have a working radiator so all the units can heat up evenly. Do you work on steam systems in the Chicago area? Because that's where I'm located.

ChicagoCooperator

Nope, not my racket, but there are plenty of others available (Steam Whisperer* to start with) in Chicago who do.

*Who just got a glowing, rave review on a south side neighborhood "google group."

maybeitssteve

Hi, @Hap_Hazzard , what do you mean by set up for hot water. If you use a two-pipe radiator for steam, is there some specific way you need to set it up? Here are some pictures of the radiator

KC_Jones

The steam vent is in the place that a hot water bleeder would be installed and is most likely the source of your problem, that is what @Hap_Hazzard meant about it being set up for hot water.

If you post a picture of the vent end of the radiator we can point out where there is a boss that can be drilled and tapped for the proper vent location.

Someone changed that radiator at some point and didn't feel like taking the effort to properly set it up for your steam system.

Hap_Hazzard

maybeitssteve said:

Hi, @Hap_Hazzard , what do you mean by set up for hot water. If you use a two-pipe radiator for steam, is there some specific way you need to set it up?

Steam radiators' sections aren't connected at the top, so the steam has to go through the bottom and rise up to fill each section. If it can move across the top, it won't fill all the sections. Moving the vent lower will help the situation, but you might still notice that it doesn't get hot at the bottom in the middle.

Some radiators are made to be used for steam or water, but if they're intended for steam, they have plugs between the sections at the top. From the way this is acting, that's clearly not the case.

ChrisJ

> @Hap_Hazzard said:
> (Quote)
> Steam radiators' sections aren't connected at the top, so the steam has to go through the bottom and rise up to fill each section. If it can move across the top, it won't fill all the sections. Moving the vent lower will help the situation, but you might still notice that it doesn't get hot at the bottom in the middle.
>
> Some radiators are made to be used for steam or water, but if they're intended for steam, they have plugs between the sections at the top. From the way this is acting, that's clearly not the case.

Plugs in between sections?
@Steamhead have you ever heard of this?

There's no plugs in mine and as I said in the other thread all 10 can heat fully and they most certainly are connected across the top. To be specific they have the special half reverse thread nipples. No rods.

Jamie Hall

Sorry, @Hap_Hazzard , but on this one I have to beg to differ. Like @ChrisJ , Cedric's home has a number (haven't counted them) of radiators ranging from cute to absurd in size. They were installed new in the structure in 1930. Every single one of them is connected across the top as well as the bottom, and all of them heat just fine, thank you.

The problem with @maybeitssteve 's radiator is -- as @KC_Jones noted, the vent is in the wrong place. Simple as that -- and just as easily fixable. Take that vent off and plug the hole. Go down the end column and find the boss for the steam vent (it's not shown in any of the pictures, but the corresponding end section used as the inlet is shown, and the boss is clearly visible. Both end sections will be alike (you can see the boss for the hot water bleeder in the picture as well)). Drill it out and tap it for the vent. Reinstall the vent. You're done.

ChrisJ

@Jamie Hall four of mine are 18 to 20 sections.

If that's not a good test of the theory I don't know what is.

Jamie Hall

ChrisJ said:

@Jamie Hall four of mine are 18 to 20 sections.



If that's not a good test of the theory I don't know what is.

Yeah, I think so too. Biggest one I have is 24 sections...

mikeg2015

I did that to mine 24 section radiator. Steam still races across but it’s manageable and doesn’t close the vent until it’s at least 2/3rd heated. The correct boss is behind the riser to the 2nd floor. I tapped a section and it work fine at the <1oz my system runs at.

maybeitssteve

@KC_Jones , thanks for your help. Here are pictures of the other side. It looks like about 3/4 of the way down there's a screw, but it has been painted over. Would that be the "boss"? Is there danger of cracking the radiator if I attempt to remove that screw? Thanks for all your help.

KC_Jones

That is the proper vent location. For reference it is much lower on top connected rads than on steam only rads to account for the exact issue you are having. The vent won’t close until steam hits it, so look at the location and you can speculate why it will work better there.

As far as getting the screw out, only way to know how it will come out is to try. I would not be concerned about cracking the radiator at all. I would use something sharp to cut the paint edge around the plug then put a screw driver in and see what you get. I’ve used small wrenches or channel locks, even my small 8” pipe wrench with the screwdriver for additional leverage (on the shank not the handle). All depends on the mechanical skill of the operator to feel when things might be turning south. Such as knowing when the screwdriver is about to slip and ruin your day.

Hap_Hazzard

Oh, my. Good luck getting that out. You'll want to use a screwdriver that fits the slot as closely as possible and that you can put a wrench on, and don't get too upset if the tip breaks off.

nicholas bonham-carter

If you have no luck with a screwdriver, then drilling, and using an Easyout might be the next step.—NBC

Jamie Hall

And if the screw brakes, don't panic. You could try a screw extractor. They sometimes work. Sometimes. And then when you get really frustrated, just drill the whole thing out and tap it for the vent...

maybeitssteve

Thanks, y'all!

mattmia2

Try a manual impact driver, i think that is the only thing that might get that plug with a screw slot out short of drilling and an easy out.

neilc

try cutting the paint at the thread and getting some oil on the thead line for a day or two,
kroil oil, pb blaster, even some tranny fluid,
tap the screw lightly each time you spot it with oil,
then go for it, as above.