Problem Steam Radiator

wanttolearn

My house is heated by steam radiators.  All of the radiators in the house are typical cast iron model (and they all work fine).  The only exception is in my master bedroom.  This one particular radiator is a different type.  Based on my online research, I think they call this type of radiator a convector type or so.

For whatever reason this radiator rarely gets warm, even when all my other radiators are running hot.  To clarify: the radiator does work somewhat when my boiler is firing for extended periods of time, but generally speaking this radiator gets warm much more rarely and slower than all my other radiators, and as a result my bedroom runs very cold in the winter. 

I have tried the following troubleshooting:

1.  This radiator is fairly close to the boiler room, and all the radiators in the nearby rooms get very warm, so I dont think it has to do with distance from the boiler.

2.  I have made sure the valve is turned all the way open.

3.  I have replaced the vent with a brand new Varivalve Quick Vent.

I am attaching three pictures for you to see.  One shows the entire radiator (approx 4 feet wide).  One shows the valve in a close-up.  One shows the vent in a closeup.

One thing I noticed is that the area around the vent shows signs of significant rusting.  Could it be that this rusting has clogged up the vent and does not allow for air to leave the vent?  If so, how do I go about opening this vent?

Another possibility is:  do I have the wrong kind of vent for this kind of radiator?  The Varivalve works well on my other radiators, but maybe it is not suitable for a convector type radiator?

Any other suggestions for what may be wrong??

STEAM DOCTOR

Radiator

1. Check to make sure that the radiator is pitched back to the supply valve.

2. Make sure that the supply valve is open.

3. Try running the boiler with the air vent removed from the radiator(obviously make sure that there are no children around).

4. When you remove the air vent try to blow through it. You should be able to blow easily.

5. Try shutting the supply valve to the other radiators.

If none of these things help then there might be some sort of blockage in the supply valve or there might be some issue with the pipes in the basement that supply the steam to that radiator. There are also other possibilities.

Did this radiator ever heat properly?

Patrick_North

Two things

I'm not a pro, but until the real thing comes along, here's a couple of things to consider.

First off, mixing and matching different types of radiators can be problematic. For example, this rad could be vastly undersized, proportionately, compared to the others. It's venting requirements will be different, too. For example, that vent is a VERY fast vent- even moreso given the small volume of air it needs to evacuate from that relatively small radiator. It may be that this vent is venting too fast. Its possible to "short circuit" a radiator so that steam reaches the vent and "shuts off" the radiator before it has a chance to get completely hot.

Second, while the shutoff valve may be in the "open" position, it's possible that some degraded parts of the valve have come loose, possibly restricting the flow of steam.

Rust around the vent hole suggests you're producing wet steam, possibly at too high an operating pressure. Are your mains well insulated? Are they well vented? Is the boiler sized properly? What is your operating pressure? Often, taking care of these types of system basics can alleviate problems manifesting at individual radiators. If you can provides some more of these details, the experts here can better assist you.

Good luck,

Patrick

Rod

Too Much Venting

I had a similar problem and what maybe happening is that the other radiators are “starving”  this one.  Vari-vents are very high capacity radiator vents. People think, that if they use Vari-vents, that the air in the radiators will exit faster and therefore the radiator will heat quicker.  While this is true that they vent a radiator quicker, there is also a big downside to this and that is that some radiators may starve.



What happens is this. With the Vari- vents,  air is quickly pushed out of the radiator and replaced by steam. This steam condenses and produces a HUGE vacuum. (When steam condenses, it goes from a cubic foot  of steam to a cubic INCH of water - about 1700 times smaller)  

   This HUGE vacuum sucks in even more steam which immediately condenses producing more vacuum. The result of this is the larger radiators compete of and hog the limited supply of steam. After these large radiators begin heating up, the condensing slows down and their demand for steam is consequently less which frees up some surplus steam that the smaller radiators like your convector. This is why this convector gets warm only, as you said, “when the boiler is firing for an extended period of time.”

You can check whether starving is the problem by shutting off the several of the large  “greedy” radiators near by on the main and seeing if that makes a difference.



If starvation is the problem, the cure is to use slower (smaller venting capacity) radiator vents.  There is an old steam adage: “Vents your mains quickly and your radiators slowly!” which seems to work pretty well.  I went through a similar situation as yours and ended up replacing my vari-vents after which the system was much better balanced and worked a lot better. Vari- Vents have their usage  but they sometimes cause more problems than they fix.  

The vent you probably want to use on that convector is a Hoffman 41 which are available from Pex Supply.

- Rod

moneypitfeeder

my 2 cents

I second looking at the piping to it with a level. sounds like a rad I had a problem with, same thin convector style. They are smaller on the inside and if the condensate needs to find its way out in a hurry. But we had a section of piping to it that had a sag, it created an airlock that steam could not get past, the only way we could tell was by cracking the line to the supply (very carefully) that must have caused enough of a pressure differential that the steam could overcome the airlock and you could hear water hammer, whoosing sloshing water trying to get to the rad and then steam would arrive.Good luck and I hope you have a warm bedroom soon!