Help Diagnosing Leak/Strange Sound With Steam Radiator

themeisle

I have a weird situation with one of my radiators I need help diagnosing. I have done a search but can’t seem to find anything similar.

I have a one pipe steam system and am noticing a strange sound coming from one of my in-wall radiators. It sounds like there is water dripping out and then hitting somewhere else on the radiator and evaporating. I hear a drip every few seconds and then a loud hiss/sizzle which I assume is the water hitting the hot radiator. Because the unit is in the wall, I am unable to see into the radiator and have not been able to find a potential leak or visually identify water coming out of the unit. There is no water dripping down onto the floor under the radiator and I am 99% sure the leak / noise is not coming from the valve knob.

What is weird is that the noise does not start right away, it only starts once the heat has been on for a 30-40 minutes and all of the radiators in the system are fully hot and pressurized. This radiator is one of the first to warm up and the sound does not start right away and oftentimes won’t start at all as the heat will cycle off before all of the radiators are full heated up. I assume the water dripping out is fully evaporating because the radiator is usually very, very hot by the time the noise starts.

Has anyone ever seen this type of issue? If there any way to diagnose this or fix the issue or do I just need to bite the bullet and replace the radiator?

Thanks for your help!

ethicalpaul

Hearing "fully pressurized" kind of alarms me. What pressure does your system get to?

In my questionable opinion, there should never be a sizzle at a radiator, since the radiator should never be above 212 degrees even at "full pressure" (which would be 0-1 PSI...mostly 0 PSI because the radiator should always be radiating causing some steam inside it to be condensing).

Could the sound be "spitting" of water and air rather than "sizzling"?

themeisle

I have the pressure turned down as low as it goes (I own "we got steam heat!") - I might be using the wrong phrasing when I say "pressurized". I just meant that the sound doesn't start until all of the radiators on the system are fully heated up, which takes around 30-40 minutes. I was thinking that until the steam fully fills all the radiators that the one I am having an issues with isn't at full "pressure"?

The sound definitely could be spitting of water and air, but it just sounds like water hitting something hot. Kind of reminds of me of what it sounds like when you put water on hot stones in a sauana. Unfortunately because this is an in-wall radiator I can't see anything.

If it was spitting water, shouldn't I noticed some wetness underneath? i can take the bottom grate off to access underneath and the valve and can't find any sign of water dripping or wetness.

EBEBRATT-Ed

Take a flashlight and look around the valve to see if the valve is leaking.

If not, take the radiator out this summer and pressure test it

themeisle

It’s not the valve (at least I am pretty sure it isn’t). The sound is coming from inside the radiator and I can’t get a good angle to see anything. See a few pics of the unit.

Jamie Hall

A radiator isn't hot enough to cause a water droplet to sizzle... so it's more likely to be air or water spitting from a vent -- or a leak. If it is a small amount, though, you won't see a water stain on the floor, as the radiator is hot enough to evaporate even a surprisingly large amount of drip.

jhrost

It may not have anything to do with your sound, but try swapping out the varivalve air vent with a slower venting model for the heck of it and see if that makes any difference.

themeisle

@jhrost will try swapping out the vent (although the sound is definitely not coming form the vent).
@Jamie Hall - I think it must be a leak of some sort then, but can't say how bad it is because i can't see in. Assuming that is the case, is my only option to get a new radiator?

Jamie Hall

themeisle said:

@jhrost will try swapping out the vent (although the sound is definitely not coming form the vent).
@Jamie Hall - I think it must be a leak of some sort then, but can't say how bad it is because i can't see in. Assuming that is the case, is my only option to get a new radiator?

Pretty much. However, if you are working very low pressure -- say half a pound or less -- you may be able to get away with JB Weld if you can actually find the leak. The secret to that is to get the metal really clean -- no paint, no rust, no grease -- before you try it.

Fred

Are you seeing a noticeable drop in the water level of the boiler? Do you have a meter on the auto water feed that you can monitor and see how much water is added each day? I don't think you will hear water sizzle but, if I were you, Even though you have the Pressuretrol set low, I'd check the pigtail and make sure it isn't clogged and allowing the pressure to rise higher than you think. I've had radiator valves leak around the bonnet because the pressure was higher than I thought. Cleaned the pigtail and leaks went away.

ethicalpaul

themeisle said:

I have the pressure turned down as low as it goes (I own "we got steam heat!") - I might be using the wrong phrasing when I say "pressurized". I just meant that the sound doesn't start until all of the radiators on the system are fully heated up, which takes around 30-40 minutes. I was thinking that until the steam fully fills all the radiators that the one I am having an issues with isn't at full "pressure"?

Cool, that all makes sense, thanks.

Does it sound like it is happening outside the radiator (like a very "close" or "nearby" sound) or might it be inside?

How is the slope of the radiator from left to right? Maybe some condensate pooling inside that the steam is shooting through?

themeisle

@Fred I dont have an autofeeder and don't notice any more of a drop in the water levels than usual (a small amount - I usually top it off a bit every week or two, which has been the norm for the two years I have lived in the house). I had the pigtail checked when I had my annual servicing at the beginning of the season...not sure I am comfortable trying to handle myself.

@ethicalpaul The sound seems to be coming inside - I initially thought it was the valve knob but I am certain that is not the issue. The slope seems level, although I am not sure how to check as it is in the wall (see the pic I posted earlier). Could be the condensate pooling as you suggest, but it is not a constant sound, it sounds like something dripping every few seconds.

ethicalpaul

Align a level with the horizontal lines on the front of the radiator. It should slope toward the pipe side. Every few seconds a puff of steam might be pushing through some pooled condensation