Air Vent for 2-Pipe Radiators

ansky

Can anyone recommend what type of air vent I should be using on a 2-pipe steam radiator? I have a 10' baseboard and a 13' baseboard and my heating guy put Hoffman HS-115 air vents on each. <a href="http://www.bellgossett.com/literature/files/7245.pdf">http://www.bellgossett.com/literature/files/7245.pdf</a>



A few people mentioned that these are designed for hot water systems. So what type of vent should I be using? Would the Heat-Timer Varivalve vents work, or are those only for 1-pipe radiators? I posted a picture of what my baseboards look like. The bottom hole on the right goes to the steam trap and the top hole on the right has the vent attached.

Dave in QCA

No Vent Needed

In a 2 pipe system, the steam trap does 2 jobs.

The first job is to act as a vent.

The second job is to let the condensation out.



The steam trap closes only in the presence of steam.  This means, that when steam is coming up and venting is needed, the trap is open and provides the function of a vent.  When the steam gets to the trap, all of the air is gone, and the trap closes.  As condensate collects at the trap, that condensate is cooler than the steam, and the trap opens just enough to let the condensate flow out.  As the steam comes in contact with the trap again, it closes.

ansky

Close vent

Thanks for the reply Dave. So my question then is, should I be keeping the Hoffman vents in the closed position (to simulate no vent at all)? I can't just remove the vent completely or there would be an open hole. I once tried keeping the Hoffman completely closed and it seems to take a very long time for the 13' baseboard to heat up. So I opened the vent just a little and it seems to speed up the time it takes for the radiator to completely heat. The reason I raised this issue is because occasionally I notice that my Vaporstat doesn't kick in, so my boiler will run continuously until the thermostat is satisfied. So I'm getting very inconsistent results with the Vaporstat. So theoretically should I be getting the best results by closing up that Hoffman?

Dave in QCA

keep it closed perhaps

You can keep it closed if you don't want to remove it and put in a proper pipe plug fitting.  

If it is taking a long time to heat, the question is whether it is heating at the same rate as other radiators and baseboards on your system.   If it is not heating when everything else is piping hot, it probably has to do with piping problems.  Perhaps a vent is needed if fixing the piping is not possible.  But, you don't have a steam vent, and the vent you have should not be used for venting steam.

When you say your vapor stat doesnt' kick in, I assume you mean that it doesn't shut your boiler off.  And, of course, it is supposed to shut off based on a pressure setting.  What is it set for?  What was the pressure?  If it is failing to shut of the boiler when the pressure exceeds the setting (and remember, they can be off calibration by an ounce or 2) then your vaporstat is faulty and needs to be replaced.



You are giving us little tid bits about your system without giving us enough information to be able to really address your problems, and whether in fact, there even is a problem.

ansky

What type of vent?

I'll try closing the vent for a longer period of time and see what happens.

Since the vent I have is not supposed to be used for steam, can you recommend a vent that is used for steam that would work on this type of radiator?

Brad White

It may be 2-pipe but

does it have traps?

If no traps, the condensate return from each radiator runs express to the wet return, usually but not always knee-high around the basement.



If you have such a system then yes, you need air vents at the radiators. Gortons, Vari-Valves, whatever is appropriate to your venting strategy so they all get hot at about the same time.



p.s. Yes, the cast iron baseboard is made for HW but they can be used with steam provided the lengths are held short. I believe nine feet is the limit, but yours seems to be well below that, at least in that photo.

ansky

Yes there are traps

Brad, yes my two radiators have traps. One baseboard is 10 feet long and the other is 13 feet long (the photo attached above was just an example of the type of radiator I have that I found online). I'm guessing that because of the long length that's probably why they added the vents to help speed up the heating of the baseboards.

Brad White

Oh good

You are right, I missed that you said the lengths and you did mention traps. Personally, I would not use the Heat Timer Vari-Valves. I have found that they spit unless the steam is very dry.



I suspect in your long radiators with low volume, you may have velocities and moisture in play more than standing cast iron would. I think the appropriate size Gorton would serve you well.



Keep in mind that your trap is an air vent first and if these radiators are unlike the others, they may heat too fast, ahead of the others.  Not sure that would be a problem. 

ansky

Which Gorton?

Can you point me to an example of what type of Gorton you think might work? I'm not too familiar with these and don't really know what to look for. Thanks.

Brad White

http://www.gorton-valves.com/specify.htm

If you go to the Gorton web site, they can assist you. Basically there are several types. Their #1 and #2 are main vents. Their radiator vents are known as #4, 5, 6, C and D, in increasing venting capacity. (The "D" has the same venting capacity as a #1, essentially a main-vent for a distant or large radiator.



Without making a project out of it, go to the Gorton site and go by their diagram. I am suspecting that because you have a trap in place (a primary air vent), you would use one of the smaller vents, a #4 or #5, as an assist. Just a guess.



These are like small hockey pucks, not the vertical cylinders you may be used to seeing.

ansky

#5

Thanks for the info. Based on the diagram I'm thinking maybe #5, because the radiator is so long (13') and there is so much air to get out it takes a long time to heat. With the vents I have now it is taking about 10 minutes to heat up from one end to the other. Does that seem reasonable?

Brad White

I would start with the

#5. There really is not that much air in a Baseray, but the vent you have now is not the type you want anyway. If any doubt, get a #5 and a #6 and try them on each one to see the difference.

Not being there, trial and error is a default.