Best radiator vents?

RobO · January 2011

I want to change the vents in my steam radiators. Can somebody recommend the brand and/or type I should use. Also, it would be great if somebody could point me to a web site where I can purchase them.

Thanks!

Dave in QCA · January 2011

Vents

There is a wide range of opinions relating to the best vents. It seems that most of the pros have their favorites, with Gorton probably being the most popular.

I have seen some system rendered completely unsatisfactory after new vents were installed, so a few questions are in order here, along with some serious evaluation before you fork over money for new vents.

1, Why do you want new vents?

2. What kind of vents do you have now?

3. Does the system work now, ie, does the steam arrive at the radiators about the same time and do they all heat at about the same rate in mild weather. That is to say, in mild weather you will have shorter heating cycles, and if the cycle is such that it heats the radiators half way, then they all should heat half way.

Tell us more about your system, any problems you may have, and what you hope to accomplish with new vents.

A very important part of venting is the main vent(s). What kind do you have now? Is it working? How long and what size of pipe are your steam main(s)?

The recommended approach to venting is "Vent your mains VERY FAST, and your radiators slow."

nicholas bonham-carter · January 2011

vent selection

very well put dave!

i will also repeat the need for capacious main vents. the majority of my 55 radiators have vents which are 40 years old; however my main vents are many and new.

the main vents do all the heavy lifting of piping/steam chest air removal, while the radiator vents only handle the air removal of the riser and radiators. they should be sized to let the air out, instead of having it pumped out under pressure by your fuel company!--nbc

RobO · January 2011

Vent replacement

I have one vent in particular which is reflecting a larger, more significant system problem I'm having. I have had an issue with wet (very wet) steam for a number of years. The system pumps this radiator, which is the closest one to the boiler, full of water. I can hear the water gushing into the radiator and gurgling while it fills up. I can see water spitting from the vent where it screws into the radiator. It appears to be either cross threaded or needs teflon tape.

After reading The Lost Art of Steam Heating I thought I had a near boiler piping issue. Specifically, my A dimension is not tall enough. Not being an expert on the subject, I recently found a contractor I trusted and had him take a look at the system. His diagnosis was consistent with what I thought. And he is coming next week to reconfigure the header and the equalizer setup. He will also replace my two main vents and change the pigtail on my Pressuretrol. I'm hoping this will address the fundamental system issue.

Now, back to my radiator vent. I wanted to fix the radiator vent so I didn't have any remaining issues. I need to remove it and replace it at a minimum to resolve the leak. Given that, I figured I would just replace it. I'm not sure if the vent is good or bad. The radiator is situated in a corner with the vent on the inside, in a very tight spot. It will be a bit of a pain to change. So I figured that if I was going to take it out, I would put a new one in while I had it out. And, if the nipple on the vent is cross threaded, I didn't want to be caught out having to hunt one down at that point. Just trying to be proactive.

Dave in QCA · January 2011

And so the remaining questions are.....

What type of vent is on this problem radiator right now? Is it the same as the rest of your radiator vents? What type of radiator vents to you have on the others?

It sounds to me that perhaps in combination with improper close boiler piping, sending lots of very wet steam up into your mains, that this radiator might be so aggressively vented that there is not much chance for the water to drain back out. But that is just a hunch.

The most important thing when selecting a vent is that it be in balance with the rest of your system, otherwise you will have problems.

I have been recently spending a great deal of time helping a friend get her steam system balanced after being knuckleheaded by a very reputable local mechanical contractor. The house is large and the rads are vented by Hoffman #40 vents. The upper floors are two-pipe, no traps, but return drip legs with the a vent installed in the drip line at the ceiling level in the basement. The first floor rads are the standard one-pipe setup. When she had a new boiler installed a couple of years ago, they replaced all of the 40s on the rads with Hoffman 1A vents, but no effort at all to balance them. They were left wide open. They didn't touch the vents at the ceiling level in the basement that were taking care of the 2nd and 3rd floor. The result was completely inadequate! There were rads all over the house that would not heat, and others that got hot immediately. The system is finally back in balance by gradually turning down the 1A vents to the slowest setting possible. All in all, this system would have worked best if they had just left the #40s in place.

Of course, they didn't even touch the to main vents, yes... they were #40 too, and way way way undersized! But this is a whole other part of the mess.

My point is, it really does make a difference what type of vent is in the rest of your radiators, and what the sizes of the various radiators are. Are they roughly the same size, or some huge and some teeny. If your system has mostly Hoffman #40 vents, except the radiator of concern, and if someone has changed it to a Heat Timer Vari-valve and it is in the wide open position..... That is a recipe for trouble and it needs to be corrected.

However, we don't know what's going on in your system until you tell us.

BobC · January 2011

radiator pitch, pressure?

Is this a single pipe steam system? If so all the radiators should be pitched so any water can drain back towards the input valve. If you find a radiator with the wrong pitch or even dead level, try putting quarters under the vent end legs to achieve some pitch. use a 2x4 and a fulcrum to gently lever them up.

Then go down cellar and put a level on the pipes to make sure they all are correctly pitched. The radiator pipes should be pitchedback towards the steam main. The mains pitch will depend what type of configuration you have. In a counterflow system the mains slope up from above the boiler to the end of each steam main; there should be a main vent after the last radiator takeoff. In a parallel flow system the steam main starts high above the boiler and gently slopes past the last radiator takeoff and then drops to a wet return so water can flow back to the boiler; the main vent is after the last radiator takeoff and before the drop down into the wet return.

Another question is what pressure is your system running at? What limits is the pressuretrol set to? Steam systems run best at low pressure, 1-1/2 PSI max is good.

Dave and nbc''s comments are valid and should be followed. Collect all the information and get back to us. Photo's of the boiler and the piping going to and from it as well as any problem radiators will help them see what your dealing with.

Bob

RobO · January 2011

Pitch and pressure

I don't know what types of vents are on the radiators. They seem to be a bit of a mix based on shapes. I don't know the difference in brands or type. But, of course, that's why I started this post! I would have to remove the one I've been referring to look at it as its hidden behind the radiator. I do know that one of them is an adjustable vent. It has a slide on it of some sort. Perhaps I should replace them all to get the system to some consistent state.

Its a single pipe system. Its a relatively small, square, two story house (28' X 28'). I have 3 radiators on each floor. The boiler is in the center of the basement. There are two mains, one that runs to each side of the house. They are about equal in length. I have a parallel pipe system in the basement where the drains run under the mains. I've checked the pitch and they are all pitched correctly. I have two main vents, one at each end of the dry returns where they drop into the wet returns

There is a wide variation in radiator size and configuration. The problematic one is the biggest. Its tall and wide. Its probably twice as big as any other one. I have two low and wide ones, two tall and thin thin ones. I can measure them and count the columns if that helps. Finally, I have one cast iron baseboard that probably replaced a older traditional radiator when an upstairs renovation was done before I bought the house.

I've checked the pitch on all the radiators. I had to shim the one I've been referring to a couple years ago. But, they are all pitched back correctly now for draining purposes.

The pressuretrol is set to cutoff at 1.5 lbs.

BobC · January 2011

venting

It sounds like your mains are about 25 ft long each and you said the vents are located on the horizontal return pipe before they drop into the wet return. the volume of each main alone is about 0.54 cu ft, so you would want a minimum of a Gorton #1 for each main vent. Do you know what kind of main vent you have now? Do you know if they are working? take a picture and we can probably ID it for you. If the main vents are clogged the radiator vents are trying to do all the work and they really don't do a good job of it.

Is the vent on the problem radiator that stuck in the corner loose? If it's just a bit loose a half dozen wraps of teflon tape might do for now. If you can buy a Hoffman 1A adjustable vent that would give you a range of 0.03CFM to 0.225CFM which should be enough. You will have to judge what kind of vent you have room for. If it's really loose you may need something like a JB Weld that will seal it in there but I don't know if you'll be able to get it back out. The right way would be to drill out that tapping to a 3/8 tapping (if there is enough meat to do it) and then reduce it down to a 1/8" tapping. the problem is you will have to remove the radiator to work on it and make sure you have room to fit everything and there is always the chance that things will go wrong - not a good thing in January.

The air vent with a lever on it is probably a Heat Timer VariValve, they are extremely aggresive and have to be used with care because venting that fast can make a wet steam situation worse.

Usually you want to vent the steam mains very quickly and the radiators slowly but all systems are different so how slowly can be a matter of experimentation.

Measure up the radiators so we know how tall, how wide and how deep each one is. Also are they 2 column, three columns deep; or perhaps they are 5 or 7 tubes deep? From that we can guess at the relative venting you need on them.

It sounds like your pressuretrol is set correctly but do you know if your pressure gauge reads ok at the bottom of it's scale. it might be worth adding an auxiliary low pressure gauge so you know exactly what pressure your running (not an urgent item right now). Also is the sight glass bouncing up and down a lot when your making steam?

good luck,

Bob

RobO · January 2011

Details...

OK. I went home and checked out all the radiators and vents in detail. The details on each radiator's dimensions and valves are listed in the attached table.

The main valves are Dole no1933. I don't think they are working now, actually. They used to hiss like crazy, but they don't make any noise now. As I mentioned above, I'm having them replaced next week by a contractor.

My mains are actually only about 12 feet long. The house is 28' wide. Each main goes from about the center of the house to about a foot from each side wall. If you were to look at the piping from the top of the house it looks basically like an "H". The radiators are placed roughly symetrically around the house. So there isn't any single one that is much further from the boiler than the others on that floor.

I removed the leaky vent, wrapped it with teflon tape and reinstalled it. This resolved the leaking issue. It is a very tight fit. The steam riser going to the NW bedroom actually runs right behind it. I have about 2" between the radiator and the riser. With the vent in place now, I can't even fit my finger between the vent and the riser.

I replaced the pressure gauge about 2 years ago when the old one jammed up. I set the pressuretrol then using the new gauge. But the new one is sticking again, so I can't really say what the pressure is right now. That raises another question: is it normal for these gauges to jam up every few years?

And, yes, the water surges in the sight glass.

So, based on the types of valves I have and the radiator sizes, should I think about swapping out the air vents?

Thanks!

Rob

RobO · January 2011

More Detail

Sorry, I'm having trouble attaching my table. So I'll try to lay it out below:

                                      Radiator Dimensions

Floor       Room     Columns     Rows      Height       Valve Type

First         Library            3                10            36"       Maid o Mist #4

First         LR                   6                14            19"       Maid o Mist #4

First         DR                   6                14           19"       Maid o Mist #4

Second   NW BR            3                  6           38"       Heat Timer Variavalve

Second   SW BR        2                   8           38"      Maid o Mist # 6

Second   NE BR/Bath    Cast Baseboard 8 'X 9"     Heat Timer Variavalve

BobC · January 2011

Venting and surging

The Dole #33 main vents should probably be at least a Hoffman 4A (0.22cfm) but a Gorton #1 (o.5cfm) would be better and I think they are a little cheaper.

The surging in the sight glass may mean the boiler has to be skimmed to clean up the boiler water. Skimming and installing main vents should calm things down.

Having your 0-30 pressure gauge fail after a couple of years prbably means they are making them out of crap these days; my neighbor has an old mummy that has to be 80 years old and that gauge works fine. The gauge may actually still work at the high end of the scale (where you never want to be), a lot people add an auxiliary 0-3PSI gauge just so they can see whats going on. A low pressure gauge can also verify the pressuretrol, they can get cranky when they get old.

The numbers below are based on tables I used that reflect what I think your radiators are. Usually you vent the radiator in proportion to the amount of air it contains. Also if one side of the house gets more wind and seems colder you could vent that side a bit faster. I wouldn't start messing with the radiator vents till you get the mains vented and your surging under control; you could well have to rebalance after the work is done so why do it more than once.

Your vent rates may be a little slow but if things are working don't change that. The Library vent does look a bit slow, it would seem you want about twice the venting capacity you have there (maybe a MoM #5?). I don't have any info on the baseboard so I can't comment on that.

Floor       Room     Columns     Rows      Height       Valve Type                    Volume

First         Library            3                10            36"       MoM #4 0.045cfm        1.25 cu ft

First         LR                   6                14            19"       MoM #4                        0.54 cu ft

First         DR                   6                14           19"       MoM #4                        0.54 cu ft

Second   NW BR            3                  6           38"       Ht Tmr    0.16-0.80cfm 0.75 cu ft

Second   SW BR        2                   8           38"      MoM # 6 0.24cfm         0.8 cu ft

Second   NE BR/Bath    Cast Baseboard 8 'X 9"         Ht Tmr                           ??

Bob

Dave in QCA · January 2011

Radiator EDR

Rob,

The EDR figures for your radiators, that is the square feet of surface area, the rating that indicates their capacity is as follows. Volume, according to chart on pg 134 of "Greening Steam" is .025xEDR for a column type radiator. Cast Iron Baseboard is .07xEDR for 10" tall baseboard.

Library = 50 sq ft, volume = 1.25 cf

LR = 70 sq ft, volume = 1.75 cf

DR = 70 sq ft, volume = 1.75 cf

NW BR = 30 sq ft, volume = .75 cf

SW BR = 32 sq ft, volume = .8 cf

NE = 20.8 sq ft. volume = 1.45

Your downstairs radiators are obviously the largest ones, and those long shorties are the biggest. Your Maid'o mist #4 vents are pretty tiny and are not adequate. Of course, the biggest venting problem is that your mains are way too small, and they are plugged. Your system is small and your mains are short, so I would go with Gorton #1 or a Hoffman #75 on each of your mains. For your downstairs radiators, the existing MOM #4 vents at .028 cfm at 1 oz of pressure. Even the old style Hoffman #40 vents almost twice as fast, at .042 cfm. I would be inclined to use Hoffman #40 on the radiators downstairs, perhaps all the way through the house. They are about the quietest vent, and are probably adequate for your radiators. Your upstairs radiators are a bit smaller, but you also have to take into account that the riser takes a little longer for the steam to arrive, so in proportion to the size of the radiator, you can vent a little faster. You could do this by using Hoffman #40 upstairs too.

Of course, another approach would be to use Hoffman 1A vents. They are adjustable. But, you will want to have them at very low settings.

I suspect that your problems of water coming into the problem radiator, while you already know is related to faulty near boiler piping, is also worsened by the fact that you have no working main vents, tiny vents downstairs. You have a couple of heat timer varivalves, depending on their setting can vent from 3-30 times faster than your MOM #4. So, if you have a leaky vent in the downstairs, that leak is doing a great deal of the total system venting, and causing water, from your wet steam producing boiler piping, to be pushed into the radiator and held there.

I'm sure many of the others on the board will provide their ideas for vents as well. The old Hoffman #40 is not very popular, but I have just spent a great deal of time balancing a system where a dozen of them were replaced with Hoffman 1A vents, they were not carefully adjusted, and the whole system was out of whack.

The Gorton's are popular, and I'm sure someone will offer a recommendation on a Gorton setup, indicating which models for each radiator.

RobO · January 2011

Bad Vent?

Thanks for the very detailed and thoughtful responses!

Two follow up questions:

1) Now that I sealed the valve on my most problematic radiator with Teflon tape, its not spitting water out around the nipple which screws into the radiator. But I now have water spitting out of the hole in the orifice on the air valve. I know I have a fundamental issue with wet steam. And that should be addressed next week when I get the near boiler piping reconfigured. But, meantime, shouldn't the valve, or more specifically, the float in the valve, seal the valve so it doesn't piss water out of the orifice.

2) The cf calculations on the living room and dining room radiators above vary significantly (the others are the same). Sorry to be critical when both of you have been so helpful. But, it seems one of you made a mistake. Can somebody please verify which numbers are correct?

Meantime, I am excited to have my piping, or more accurately, my boiler's piping, reconfigured next week. I'll post an update when its all done.

Thanks again,

Rob

BobC · January 2011

calcium buildup?

Your newly sealed vent may have a calcium buildup that is preventing the vent from closing completely. You could try swapping it with one of the others to test that theory. You could try boiling that vent in white vinegar for 15-30 minutes and see if that fixes it. By the way one thing to be careful about the Heat Timers is they do not have a float so they can spit water under the right circumstances.

i agree with Dave on the Maid o Mists being on the small side. I would wait till the main vent is installed to get fussy with the radiator venting rates. Then you will have to decide between fixed or adjustable vents.

As to the volume of those two long low radiators I based my numbers on them being 19" tall and 6 tubes per section (1930?) - 3 cu ft per section X 14 sections = 42sq ft. For that area I used a volume of 0.013Cu Ft / Sq ft which works out to .013 X 42 = 0.546 Cu ft for that radiator. That is all assuming I selected the correct radiator type from my copy of Dan's books. That is my best guess.

Dave in QCA · January 2011

tube or column type??

Bob, I used figures for column type radiator for both the shorties and the 38" tall rads. I looks like you used figures for column type for the tall ones, and for large tube radiators for the short ones. I assumed that since he counted the number of columns in his chart, that we were dealing with column type rads all around. Perhaps I missed something. If they are column types, the sq ft per section for a 6 column rad is 5. Since I was thinking they were column type, I used .025 as the multiplier for volume. So, my calculations were 14 sections x 5 sq ft/sec=70 sq ft. For Volume, 70 sq ft x .025 cu ft/sq ft = 1.75 cu ft

Do we need to confirm whether these are Column or large tube radiators? If so, I posted a bunch of pictures on a thread a couple of days ago. It is.... http://www.heatinghelp.com/forum-thread/133585/Radiator-sizing-questoins#p1214756

Dave

BobC · January 2011

We don't know

Dave,

i think you've nailed it. i assumed they were tube radiators but I really don't know. Let's hope the homeowner looks at that link and tells us which type of radiators he has.

have a great weekend,

Bob

Dave in QCA · January 2011

Happy 2nd weekend of the new year!

Bob, Thanks for the reply back. I am uploading a file that I scanned the other day. It is another very useful source for EDR information.

Also, A spent the day helping a friend with her very old steam system. One pipe on the first floor, 2-pipe to the upper floors, no traps, but a valve at each end of the rad. The return pipes have a vent in them at the basement ceiling level, and then they drop on down to a wet return. A rather ingenious and unique way to do it. It allowed for much smaller risers to the upper floors. I am going to try to get some photos and post on it, because it is different than anything I have ever seen before.

~Dave

Best radiator vents?

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