Missing Orifice?

vaporvac

Hello all,



Firstly, I'd like to thank everyone who responded with such helpful comments to my last posts concerning my Trane VaporVac 2-pipe gas system.   I also apologize for writing personally to a few replies.  I was feeling pretty desperate as I'm unable to post from my own computer and wasn't sure for how long the boiler would hold out . (Still not sure of that).  Anyway, the small changes I made have really helped.  I continue to try to troubleshoot the existing problems before replacing the boiler.



Most  recently, I noticed a 3rd floor radiator that  heated up last year had gone completely cold.  Even the inlet pipe was frigid.  The riser it runs off also feeds another radiator on the 2ndd floor that was HOT. Oddly enough, when I removed the outlet ring air came rushing out.  There are no traps on this system. Why did air come out if no steam was getting in? 

I then removed the inlet valve, and freed the entire radiator.  When I blew through the rad, dirty water came flying out. so I assumed no obstruction.  The valve did open and close, although the area where it seats was full of a nasty black liquid, possibly from old packing?  How do I repair this?  It is a Hoffman Equipped valve. There are no orifices at either inlet or outlet;.  should there be?  Is the valve the only thing controlling the amount of steam entering the rad ?  I recall Jamie has a Hoffman Equipped system.  What should the valves be like and where are the orifices, if any?



I should say that after this little experiment, the radiator heats!!!  I just don't know what precisely I did to affect this?  Possibly blowing through the rad?



I'm trying to fine tune the balance and wonder if I should check for orifices, etc in the other rads.  I still have many problems, but until I can consistently post with schematics, I'll hold off with further questions.  Again, thanks.  I don't know how endless hour were filled before i found this site!



Colleen

Jamie Hall

Hoffman Equipped

Most Hoffman Equipped systems did have traps on the radiators, but they didn't have to.  It did not have orifices.  However, what it did have is the valves -- which you seem to still have! -- and they could be adjusted to regulate the flow of steam to the radiator.  That is, they have an internal adjustment as well as the external lever handle.  Ideally, the internal adjustment (effectively a variable orifice) was set to the size of the radiator when they were installed (although this often was left out...) and then the homeowner regulated the heat given by the radiator with the external handle.  If the internal adjustment wasn't made -- and, as I say, the dead men weren't perfect and that step was often skipped -- you can achieve the same effect by simply not opening the valve all the way.  It almost sounds, though, as though you are one of the fortunate ones with a Hoffman Equipped system where the valves were properly adjusted.  If you are patient, you can set the valve so that the radiator heats almost all the way, but not quite, and the outlet pipe is very warm but not steam hot, and achieve all the results that could be achieved with an orifice!  In a pinch, you can even compensate for a failed trap this way.  There is a diagram of a Hoffman Equipped valve in the catalogue -- http://www.heatinghelp.com/files/articles/1308/89.pdf



As to why the radiator heats now and didn't before, well... um... possibly blowing out the radiator did it; more likely something in the valve was amiss, and you have managed -- quite unintentionally! -- to fix it.  I've done that, more than once.  The nasty black liquid?  Don't know.  Might be a failed packing, but I doubt it -- while they did have a packing, it was just around the outside lever, and was metallic and shouldn't fail (right...)(the same catalogue entry above says cheerfully that the valve lever can be turned with light finger pressure.  Don't I wish...)  Might also be accumulated condensate.

vaporvac

mystery gunk

Thanks for the reply.  I never thought I'd rue 66deg weather in Feb., but I really want to fire up that radiator!  The pdf on the Hoffman valves was very informative; mine definitely lacks that internal mechanism and doesn't have the gradations.  Would it be worthwhile putting an orifice in as suggested in various threads? Mine system is a Trane vaporvacuum and some of my valves are the original Trane.  They look very similar to those Hoffman and the article has helped explain the settings on them.  Some only move a fraction between the open and closed position.  I also think I have two other Hoffmans that are similar to the pictures.  The one in the bathroom is just a roundish handle, perhaps a later replacement. Were all Hoffmans meant to induce  vacuum.   I have a motley assortment of valves including Dunham and Detroit Original so I'm wondering if I should mess with them or just be happy they get heat. I'd be willing to go the orifice route if I thought it would help with the vacuum.



BTW, what prevents the steam from leaving the radiators as soon as it enters if there are no traps?  The system currently only pulls a vacuum of about 2 inches.  I'd obviously like it to be much greater, but am sure the leaky boiler  and air valve on one radiator don't help. How does one go about removing and  plugging an air valve.  It shouldn't be there and was obviously put there by some knucklehead. We used to think all the radiators should have had them.  I'm just glad we didn't go ahead and install more!



Regarding the black gunk;  it's almost like indelible ink and is located where the valve comes to rest in the off position.  Were there any gaskets or seals there? It just look like something was once there originally and I'd like to replace if practical.  Thanks everyone for the input. Hopefully, the answers to my questions can help others.



Colleen

Jamie Hall

Let's see here...

Why doesn't the steam go whistling out of the radiator as soon as it gets in, if there are no traps?  Because it condenses in the radiator before it has a chance to.  The objective of the orifice or properly adjusted valve is to limit the flow of steam to just slightly less than what the radiator can condense.  This, however, is very sensitive indeed to pressure!  If you are depending on orifices or valves, rather than traps, you absolutely must use a vapourstat, and it must be properly calibrated and set to limit the pressure to -- in most vapour systems -- 6 ounces or so.  Otherwise, the steam will go through the radiators -- which is a waste of money, if nothing else.



Vacuum systems required vacuum vents -- Hoffman still makes them -- to allow them to pull a vacuum when the fire died down (note that I don't say turned off).  Most modern vents won't close against a vacuum, and let air in as fast as can be.  With modern burners -- which are mostly either on full song, or off -- and modern boilers, which are tiny compared with those we had in the day! -- I honestly don't think that there is much advantage to trying to hold a vacuum.  With coal fires and huge boilers which took forever to cool off, a system holding a vacuum could still produce steam, although at a lower temperature, when the fire was banked or was allowed to die down because of the vacuum.  This gave you a lot of flexibility in managing the fire, which was a big help.  Then.  Not now.



It's easy to remove a radiator vent -- get a plug (plumbing supply store; big box or hardward sometimes) the same size as the vent.  Unscrew the vent, put a bit of pipe dope on the plug, screw it in tight and that's it.



I wouldn't worry about the mix of valves, so long as they turn on and off.  I'd leave 'em be.



Orifices wouldn't make any difference to the vacuum bit.



I still have no idea what the gunk is... maybe someone else will.

Rod

Inlet Orifices

Hi - Steam is lighter than air so it tends to fill the top of the radiator first and then work its way down from there, condensing back to water as it touches the cold inside surfaces of the radiator. Using an orifice or a metering valve, the idea is to allow just enough flow of steam into the radiator to match the condensing surface so therefore steam never reaches the outlet, it condenses first  The orifice size/ valve setting is sized to match the size of the radiator. With the inlet valve metered/ orifice sized properly, the radiator will never completely get (steam) hot close to the exit pipe.  Have you read Henry Gifford's article on radiator orifices?

- Rod

vaporvac

Should the valves have a gasket?

Thanks for those latest replies. That totally explained the issue of what keeps the steam in the rads.  As I lowered my pressures down to about 6oz. with a 2oz diff. based on my prior posts re short cycling, I think I may be good.  I hadn't really thought of the relationship between the two, but now realize my rads  staying warm so MUCH longer must be due to this!

 I did actually read Gifford's article on orifices which is what got me thinking in the first place of inspecting all the rads and installing them.  Not sure that I'll due that at the moment.

I still need an answer about any seal/gasket  at the bottom of the valve that would ensure a perfect closure.  I can't tell from the Hoffman article if they have anything like that.  Do valves usually?  The black gunk just looks and feels like a dissolved seal. 

Any input would be appreciated.

I'll leave the subject of vacuums to another post!

Thanks again.



Colleen

Mike Kusiak_2

Sealing washer?

Are you describing the sealing washer which mates with the valve seat at the bottom of the valve? There was a discussion recently about making replacement washers for old radiator valves:



http://www.heatinghelp.com/forum-thread/75498/steam-valve-washers-rubber-composition-disks

vaporvac

That's exactly what I mean!

That is just what I meant!  I think I may have some of that high-temp gasket stuff lying around.  Does it have to be a specific thickness? Do the old ones just fail after so long...I should probably check them all. Is their purpose to completely close off the valve or something else?

Wow!  All of my original questions answered which, as usual, only leads to more questions. Hopefully, when the boiler goes back on, the radiator will still heat.



Thanks.

CD

Rod

Valve Seal

Hi - Attached is a PDF on the Hoffman No. 7. It is very similar (uses the same artwork) as the one Jamie posted though there are a few phrases more describing it. I've never seen one of these valves but from the description it would

seem there is a seal on the end of the stem (sort of like a Jenkins

disc) to shut off the valve. I would be amazed if any of the original seals were still there. Rubber seals in those days had no where near the durability they have now though I doubt if even a seal made out of modern materials would last 75 + years! 

 Mike gave you a good lead. McMaster Carr has all sorts of high temp materials - a lot of valve seals are now PTFE (Teflon) though there are also lot of other good materials to choose from.

- Rod