Single Steam Radiator isn't Heating Up

MrVince

Need some advice. I have a single-pipe system in a house. The radiator is located in an addition that's nearby. The radiator doesn't heat every quickly even when I remove the radiator vent. When other radiators in the home are hot, this radiator is lukewarm (with the value completely removed). I can hear a lot of water gurgling.

By the time that the rest of the house gets warm and turns off the thermostat, the room is only slightly warm. The radiator barely gets hot enough so that steam starts to spit into the room (from the open radiator vent) for only a few minutes.

The main that services this small-room addition doesn't have a main vent. The pitch of the main pipe that leads to the room isn't slanted. It's very even. And the pipe has actually developed a slight bend to it so I can see water collecting there. I'm guessing this is the cause of the water gurgling.

But would this cause the steam from reaching the radiator or is there another issue? It's not like water would be blocking the steam from getting to the radiator…

Fixing the piping would be a pretty expensive endeavor. Is there anything else I can do?

Any advice welcome!

delcrossv

Try to remove the sag, then a vent at the end of that main may help. The gurgling and no joy with the vent removed leads me to think waterseal/pitch problem. Pools of water are very good at condensing steam.

Pictures of the saggy main and riser connection would be helpful.

STEAM DOCTOR

Was this radiator added when the extension was done? If yes then the piping is always suspect. Seen this endless times. General contractors think that you can slap steam pipes together and expect everything to work.

ethicalpaul

If I could, I would bet $1,000 the pooling water is the problem. If there's an open path, steam will take it, so there must not be an open path, by definition.

EdTheHeaterMan

Single Steam Radiator isn't Heating Up

Maybe it is lonely, have you tried a dating app for radiators?

bburd

It may be possible to correct the pipe pitch by shimming the radiator on all of its legs so it sits a bit higher, and possibly adding or adjusting pipe hangers.

Try to think as if you were water in the bottom of the pipe. How would you get back to the boiler without interfering with steam flow?

Jamie Hall

"But would this cause the steam from reaching the radiator or is there another issue? It's not like water would be blocking the steam from getting to the radiator."

Oh yes it would. A moderately sized puddle of condensate is astonishingly good at blocking the steam flow!

The problem is that steam in your pipes is just at the point of condensing. When it passes over standing water, that's exactly what it does do, and none of it will get by until the entire puddle is heated to full steam temperature — and even then, very little will, as the energy in the steam will try to evaporate some of the puddle, which will then recondense, and so on.

Fix the sag.

STEAM DOCTOR

Always worth a try. But depending on how the piping is arranged beneath the floor, you might actually make the problem worse. Impossible to know. Maybe a thermal camera can help. Maybe

STEAM DOCTOR

In my travels, it's usually not a pitch issue. More of a excessive length of horizontal piping and coupled with the undersizing of that piping

MrVince

https://forum.heatinghelp.com/discussion/comment/1815832#Comment_1815832

I didn't realize that pools of water would actually "block" the steam flow by condensing it. But, now, that you say it, it makes sense. Water has a high specific heat capacity. Steam will keep going pass it and heating up the water.

It's hard to tell in the attached picture but the slant isn't that bad although it is slightly slanted in the wrong direction. The problem is the pipe actually has a curve to it. I don't know how that happened. 😆

I was hoping the issue was something else. It sounds expensive to get a guy to actually shorten the main riser coming out of the boiler to achieve the correct slant. sigh…

MrVince

https://forum.heatinghelp.com/discussion/comment/1815833#Comment_1815833

Yep, the radiator wasn't part of the original home. It was added when the addition was added to the home decades ago.

You are right about it doesn't seem like it was put together well. Several portions of the piping to the radiator doesn't seem to have sufficient slope in it. Actually, slopes in the opposite direction. ☹

MrVince

Bburd,

Will do. Thanks for the advice.

delcrossv

https://forum.heatinghelp.com/discussion/comment/1816006#Comment_1816006

"slopes in the wrong direction"

Yeah, that'll do it.

ethicalpaul

Steam will keep going pass it and heating up the water.

I will offer the counter opinion that steam will not go past it, but will instead instantly condense, sometimes causing water hammer, until the steam has given up enough heat to warm the water to the point where it will indeed allow the steam to pass.

This is why in this very common condition, the radiator will eventually heat up on a long call for heat.

Jamie Hall

And I will agree with @ethicalpaul 's counter opinion up there, with bells on. Steam will NOT pass a puddle of water in a sagged or poorly pitched pipe, until the entire puddle is up to steam temperature — which will take a good bit of time.