Air vent questions

ba123

First, apologies because I suspect this is a common question, though search did not locate anything.



Two issues:



(1)  I've got a 1-pipe steam system.  I've installed Hoffman 1A vents on most of the radiators and they work great.  Problem is that about 2 or 3 of these vents seem to fail every year.  "Fail" in this case means they no longer close when steam hits them, but just stay open with the steam coming out.  If I replace with a new 1A, all is well, but at $30 or so each this is getting expensive.



I've tried to pitch all raditaors away from the vent/toward the valve.  When I remove a failed vent, it does not seem to be filled with water, maybe a few drops but that's all.



Are these vents expected to fail over time?  Is there any way to revive a failed vent?





(2) I'm mystified by the Heat Timer Vari-Valves  I decided to try a few but I can't get these things to vent *at all*.  As in, whatever radiator I install one in remains completely cold no matter how I adjust the vent.  If I replace the Vari-Valve with a Hoffman 1A, the radiator works fine.  Suggestions?



Thanks for any help.

Patrick_North

Hmmm...

Re: #1- no, they shouldn't be failing with such regularity. Is it possible that you're boiler is operating at elevated pressures? High pressure among other things can ruin these vents in short order. What is your pressuretrol/vaporstat set at? Do you have a low pressure gauge (in addition to the code required 0-30# gauge) to monitor system pressure?

Re:#2- this is surprising. The vari-valve is a very fast vent- as in several times faster than the Hoffman. Can you blow air through the vent (make sure it's pointing upright)? Do you have the vent at its highest (wide open) setting?



Patrick

JeffM

strange indeed

That is strange behavior from the Vari-Valves. Even with the slider completely closed, these tend to vent a lot of air (I have a few on a 1-pipe system that doesn't currently have any main vents).

ba123

Follow-up...

Thanks for the suggestions.



For (1) -- I'm not at home now, but I know the pressuretrol (Honeywell unit, I believe) is set to the lowest possible setting, something around 0.5psi.  I've seen the boiler cut out when the pressure gauge on the pressuretrol reached this level, so I assume the pressure is appropriately low for this residential system.  I don't think we have a low pressure gauge, if I understand correctly.  There is a gauge attached to the pressuretrol, but full scale on that is probably 10-20psi (again, not at home to check).



In reading some of the comments to other posts, I'm now also wondering if the main vent might be not working as well as it should.  I will try to check that, since I assume a bad main vent might lead to a temporary rise in system pressure as the radiator vents slowly bleed the air?





For (2) -- Amazingly, yes, I have tried blowing thru the VariValves with my mouth.  Blew as hard as I could and never got any air thru it, no matter how I set the slider.  I have 6 of them, and they're all the same.  Maybe I got a bad batch?

Patrick_North

Spooked vents

I’m stumped on the Vari-Valve question. Some people don’t care for them because they vent so fast, so your problem is ironic to say the least. Can’t hurt to return them for replacements.

Without a low pressure gauge it's difficult to assess system pressure. Pressuretrols are notoriously inaccurate at the low pressures desirable in a steam system. Consider adding one- it's not a big investment and it can tell you a lot about your system. Also, if you suspect your main vents are inadequate they could certainly contribute to higher operating pressures.

As to the Hoffmans, my experience has not been favorable, though many people do like them. I was attracted to them because of the ability to fine tune the venting rate, but found that even when producing dry steam at low pressure and with radiators properly sloped the vents would collect water and eventually stop working. Some would merely gurgle/hiss as if under extreme pressure when shut (though my system cuts out at under 1#). Maybe this is what you are experiencing. I can’t be sure but I suspected dirt/condensate was preventing a good seat on the supposedly shut valve. I’ve since replaced all of my Hoffman 1As with Gorton vents- problem solved. Some folks have had luck with boiling fouled vents in a vinegar solution, but frankly, I think the 1A is just not a great design.

If you’re antsy about giving up on variable capacity vents, (heck, even if you’re not) I recommend looking at “Balancing Steam Systems Using a Venting Capacity Chart,” available through this site. It’s a quick read, but it’s packed with clear, actionable info. For me it has been very helpful in selecting the right vents (for both mains and rads) and knowing why they were the right ones. You may find, for example, that mixing those high capacity Vari-Valves (if you ever get them to work!) with the more modest Hoffmans causes new problems.

Good luck,

Patrick

nicholas bonham-carter

Venting problems

Do you have any main vents? If not the the poor rad vents are trying to do something which they do not have the capacity for: venting the mains, and steam chest of the boiler.

If in spite of the low settings on the pressuretrol, the pressure has gone up too high, then all the debris in the system may be inside the radiator vents.

Put on your to-do list the following:

0-3psi gauge.

More main vents

Nbc

Long Beach Ed

Vari-Vents

Sure you're not holding the Vari-Vent's upside down?  



We've had lots of trouble with them, but not like you're having.  They'va all worked great out of the box.  About 3/4 of the Vari-Vents we've installed have failed closed in the first year.   They have a design defect which permits the silphon to dis-attach from its top mount and fall closed.  



We've tried and tried to alert to manufacturer to this problem but they haven't even answered our correspondence, no less replaced the dozens of worthless valves we've thrown away. 

ChrisJ

Hoffman 1A

I too have problems with a random Hoffman 1A getting water in the top orifice where it vents occasionally.  My system runs at less than an ounce most of the time and just a drop of water in that opening is enough to stop a radiator from heating.



What I have found is tapping on the valve with my fingernail right when the system shuts down is enough to clear the water if it happens.  If this doesn't work removing the nut on the top by unscrewing it and then using a can of air with its plastic hose can clear the water.



I have not had them fail to seal,  yet....



Chances are mine may get replaced with Gorton's slowly.

ba123

Follow-up #2

Thanks again for the help.



Yup, I'm sure the VariValve was right side up, both when I was blowing into it with my mouth and when I  installed on the radiator.  No air was vented in either case.  I'm just going to give up on them.  I think I prefer the Hoffmans and, recently, Gortons anyway.



In terms of main vents, we have just one main vent as far as I know (old house, we didn't install the system, and some of the piping is hard to see).  The main vent failed stuck open a few years ago and was replaced, but I don't know with what.



How would I verify that the main vent is working properly?  It works like the radiator vents and opens until steam hits it?  Can I just listen to it rather than trying to get near it to feel the air being vented? It's in a location that is hard to reach without taking a piece out of a wall, and the wife surely would not approve of that...



Will add a 0-3psi gauge to the to-do list for warm weather in case I muck it up and need to call a pro.

Long Beach Ed

Pressure

As Patrick was getting at,  vents often fail when pressure is too high.  Among other problems, it causes dirt to get into them.  Your system can also be very dirty. 



Make sure the pressuretrol is set low -- to about a pound or pound and a half.  Make sure the pigtail leading to it is unclogged.  Make sure your main vents work.  Either remove them and blow through them, or feel with a wet finger or look with smoke to see that they are venting air and closing when hot. 



If your system is making wet steam -- if piped incorrectly -- this will also shorten a vent's lifespan. 



We like Gorton vents.  They seem to take the most abuse, though the Hoffmans serve very well on good systems.  Both will outlive all of us if treated right.   

conversiontime

hoffman 1a design flaw

Must be something in the modern hoffman 1a design that is causing water droplet vacuum. I ordered a sixer of 1a_s in October because the 15 year old ones on some rads still work great. But this new batch has the same problem chrisj mentions, it appears they become vacuum plug with condensate and then rad goes cold. I have had to remove and drain a small amount of water out of the same 2-3 ones multiple times already. I changed them out on some other rads to see it it helped (did not).  Cannot recommend this valve until design flaw is fixed esp given the price point.

ChrisJ

water problems

Though it sounds mean I'm glad to see others are having the same problem.  I just had two more of them do it recently though one was only partial.



Sometimes its enough to stop the radiator from heating until I blow into the top of the vent with a can of air + straw, but sometimes it just slows the venting up.



My hopes are to swap all of my almost new 1As with equivalent Gorton's for whatever my approximate settings are.