radiator steam traps vertical pattern single union

Al_Service

In an old church in rural Virginia with a two pipe steam system (about 3 psi) built about 1950, I have learned that apparently none of the 70 or 80  1/2" steam traps at the convectors have been replaced for about 25 years. (some are still working and the system has been in use every winter).  Some rooms do not heat and I am convinced there is too much pressure in the condensate side.  Most of these traps are vertical pattern single union radiator traps.  There appear to be 4 or 5 different makes.  I am having trouble locating traps of this pattern which I fear is about obsolete. The inlet is centered and the outlet is on one side but turns upward with a union on top.

Can anyone recommend how to proceed and maybe which brand to go with? The majority of the old ones seem to be Hoffman Specialty. Much appreciated.

JStar

Traps

Instead of spending a lot of money on trap upgrades, you could remove their elements and install orifice plates in all of the radiator supply valves. If you do want to change that many traps, you can look at Barnes & Jones or Tunstall for parts.

Al_Service

orifice plates?

Orifice plates sound better to me if they will work. I can remove the trap elements but there are no radiator supply valves.  I can put orifice plates in the unions at the supply side of the convectors.  I'm interested in hearing from anyone who has made this kind of change successfully. Is the size of orifice something which needs to be determined by experimenting or can it be calculated?

JStar

Orifice plates

We install orifice plates in almost all of our two-pipe systems with great success. They can be installed in unions as well as supply valves. They allow you to remove the traps, which need to be maintained and replaced every 10 years or so. The size of the orifice is very precisely calculated. The sizing charts are top secret, though. Talk to TUNSTALL and they can make them for you.

nicholas bonham-carter

Hoffman system

I wonder if the system was designed to run sub-atmospherically ie. vacuum.

Perhaps the pressure was raised to push the air out of some badly maintained main vent.--NBC

Al_Service

orifice plates?

I don't think this was ever a vacuum system. 



I appreciate any and all suggestions about converting this system to orifice plates and I will be talking to Tunstall. 



A big question is this: Don't the orifice sizes need to be calculated from the given pressure?  The radiator steam traps have been bad so long that many well-meaning people have tried adjusting the pressuretrol.  I am not sure what pressure to use to design the orifice sizes.

Jamie Hall

Top secret?!

Joe, I love it.



You are right, though -- sizing the orifices is a bit of a hit or miss proposition, although there are sizing guides which can get you close.



In answer to the pressure question, you can make an orifice controlled system work on almost any pressure, believe it or not -- but it is much much easier to make it work on a very low pressure, such as you can achieve with a vapourstat set to cutout somewhere around 12 ounces or so, and cut back in around 6.  That should be all the pressure you would ever need for this system.

Fizz

Copy of proper siziing of orifice chart

Attached is copy of orifice chart sizing plate edr and pressure of steam. Hope it helps.

nicholas bonham-carter

A very useful chart

It makes me think that a good supply valve could also be used to regulate the steam, and indeed why not regular steam valves adjusted with a very careful hand, and relying on no knuckleheads to disturb the settings.

Sadly the poster here has no such option, as he has no valves.---NBC

Al_Service

Useful chart

Thanks for the chart and the rest of the advice.



This is all encouraging, however, we had hoped to fix one zone at a time for budget reasons and there are three zones on the boiler. I am hearing here that the orifice plates ought to work fine and that lowering the pressure a lot more ought to work fine.  I have already lowered the pressure in stages over several winters from about 7.5 psi to 2.5-3 psi. (Previous service men convinced the owners the system needed more pressure). I wonder whether if we lower the pressure to one psi or less (buying a vaporstat), we ought to go ahead and convert the whole building to orifice plates.  I am optimistic and I'd like to try it, but there is reluctance here to make so many changes at once.



To be clear, what I want to do is go around to about 80 convector type radiators, remove all the trap elements, add orifices to all the supply unions, and lower the boiler pressure to match what we sized the orifices to.  Then turn on the heat in the fall and hope it all works better than before. 



Not to sound doubtful, but I keep wondering, if orifices vs radiator traps are such a good idea, why didn't the old guys build systems this way in the first place?  I have never seen them.  (in Virginia)

Jamie Hall

They did build them that way

In fact, there are a lot of systems which were built with orifices.  There are a lot more systems which were built -- as nicholas noted -- using valves for the same purpose (the one in the place I take care of is in that category).



Traps on such a system are somewhat in the belt and braces category -- they serve to control things in two situations: first, someone monkeys with the valve and gets it open too far and, second, somehow the pressure gets too high.



I'm reaching a bit out on a limb here, but it is my feeling that you won't be any worse off if you reduce the pressure first, and I'd be very much inclined to bring it right down to about 12 ounces cutoff with a vapourstat.  If your church just doesn't have the cash to do that, try taking the existing pressuretrol as low as you can get it to work reliably, which will probably be around a pound and a half cutoff.



This won't hurt anything at all.



Then start with one zone, and put orifices on the convectors which have failed traps first.



Then do the next zone, and so on.



Then go back and work on the ones you didn't do the first time around.



Believe me, I sympathise with the budget woes of churches...

Al_Service

They did?

I meant old systems with orifices or valves and without traps.  It seems they almost always had traps.





I wonder why didn't they simply leave out the traps and valves and use orifices alone if indeed it works so well that way?  Less reliable pressure controls in 1950 maybe?  Or fear that someone would eventually raise the pressure?





I am getting the idea there would need to be a posted sign warning not to raise the pressure due to no radiator traps...and of course I get it that we effectively have no traps now.



A vaporstat could probably be in the budget if indeed we are saved from buying all those dreaded traps.

vaporvac

Yes, on old systems.

Many, many old two-pipe systems have orifices and the metered valves. These were generally higher-end systems. My own two-pipe Trane vaporvacuum system has the metered valves, but where some were replaced over the years, I'll be putting in orifices. I'm not sure if anyone still makes the metered valves.

I don't know the history of traps, either when or why they were introduced, but many early systems lacked them; maybe it's like today when there's planned obsolescence! Once you have traps, you have to maintain them. I also had some knuckleheads over the years tell me I had to ADD traps because my system couldn't possibly be working correctly without them!



I'd follow Jamie's advice and lower that pressure STAT, then look into adding a Vstat and orifices. Don't worry about lowering it further; it can go much lower. For comparison, the Empire State Building runs on about 2 1/2lbs of pressure! You can get a Vaporstat for less than the price of ONE new trap. The pre-drilled orifices are not expensive, but if you use the charts, you could custom-drill the blank ones that are sold for even less.



I might also add that a properly vented system will not allow the pressure to go too high. Without any vstat on my newly installed boilers, the pressure rarely reached over 1lb and generally never exceeded 1/2lb. I had the pressuretroll set for 2 with a cut-out of 1.



I also wouldn't be too sure your system wasn't designed to run in a vacuum as many folks here have discovered. Good luck.

Colleen

gerry gill

the original Mouat systems didn't

have traps..neither did OE systems, or Broomell systems and countless others. A radiator can either have its steam controlled at the entrance door or the exit door..its easier to do the exit door..you can also run the system at higher pressure (like 2 or 3 pounds) if the exit door for the radiator is trapped and a boiler return trap is used..that may explain the transition to steam traps instead of graduated, metering inlet valves..Mepco still makes those inlet valves though if your interested.

nicholas bonham-carter

Traps vs orifices

The steam trap was probably seen as a better way of getting the steam into the radiator,quickly, because of its larger opening, (when cold). The orifice can slow down the arrival of steam, during recovery. This is just another reason not to use short term setbacks.--NBC

Al_Service

Adding orifices and removing traps

Ok, thanks everybody, this is all helpful.



I read 'the lost art of steam heat' years ago and I don't remember anything about removing radiator traps and adding orifice plates. 



The main idea that stayed with me is that most problems are caused by changing or removing things the "dead men" had provided in steam systems.  I have great respect for how it was and great timidity about abandoning anything in this old system.  This is why I keep wondering what is the down side (what might be lost) if I add orifice plates and don't maintain the traps. The church has money right now to address radiator traps and I want to use the opportunity in the best possible way for the long term.



So far I have heard of only two possible negative results of this change:

Loss of a safety system against too-high pressure, and

Potentially slightly slower recovery after setback.



I think these two are acceptable, so will try to proceed and hope we never need to add back those traps because who knows when there may be another budgeting opportunity. I'll keep checking this thread.



Al

jumper

dual orifices?

At the exit of a terminal you want to hold back steam while letting air and condensate through. At the entrance you want to retard steam to prevent overheating. To do the latter you keep putting in smaller orifices until you're satisfied. Lost Art describes devices to perform functions of steam traps. That traps are the most common indicates either that those devices were unsatisfactory or that trap vendors were effective.

Al_Service

Add orifice plates, abandon radiator traps

I've been talking to the Tunstall people about calculating the orifice sizes to limit the steam to amounts the convectors will condense, but they keep telling me I should still maintain the steam traps (by buying their capsules) as well as install the orifices.  We think this shouldn't be necessary if the calculation is correct for the pressure and room temp.



I'm going ahead with the orifices alone, but against Tunstall's recommendation.  Hope this works. Thanks again for reassurances.



Al

Al_Service

A hitch in converting to orifice plates...

I can't believe I didn't think of this sooner -



1. The success of removing the radiator traps depends on calculating the EDR of each convector and sizing the orifice to limit the steam to an amount the unit can condense.

2. Tunstall (making the calculations and supplying orifice plates) wants to know the outside dimensions of the units and the pressure.  And they say we still need the traps.

3. There are no input valves, just manual internal air dampers which are sheet metal flaps closing over the finned tubes for room temperature control (one of the thermostat zones has 16 Sunday school rooms).

4. But if the damper is closed, the finned tube can't let go of its heat at the same rate and that convector won't be able to condense nearly as much steam!  Some of the steam will shoot right through into the returns!  So THAT is why the traps are needed.

5. Unless we fasten the dampers open...here is a photo of a convector with the front removed.



Most of the damper chains are broken and the plan is to restore them.

So, restoring the dampers means we would need to restore the traps.

Abandoning the radiator traps means we would need to block the dampers open.

I'm thinking that even w/o dampers and w/o traps, the orifice plates will make the system will work far better than it has for decades.  I'm for keeping it simple, at least for now.



Any other ideas?



And thanks again to all for your input, especially  JStar, Jamie Hall, and Fizz,

Al

BTOW2MMR

go with barnes `n jones

I worked on an old campus years ago as a steamfitter. Rebuilt alot of the same traps you`re talking about. Barnes `n Jones had the internals for any trap (some manufactured in 1917) ever made. Easy to deal with too good luck.  Deepwell socket does the trick.

Al_Service

I need help with orifice plate sizing.

We are working on the input union orifice plate solution. Can't find the helpful pdf chart that Fizz kindly attached on here "orifice sizing based on edr and pressure of steam". I was sure I had downloaded and printed it but it has disappeared! Could you please send it again?

Thanks!

Bio

Find some info here http://www.energysavingscience.com click on orifice article

Al_Service

Thanks, I got that. Still need the chart that was posted here on August 13 if anyone can find and repost it. Thanks!

BobC

Page 5 of this article might be what your looking for -

https://78462f86-a-1c056b1f-s-sites.googlegroups.com/a/energysavingscience.com/www/articles/henrysarticles/BSEOrifices.pdf?attachauth=ANoY7cq0HC9Clv6Kd3dyIWa7P3m-UJPkYxy207TAWvCH9vDw4xSVg4-pCh3gusB6AlzniG9KSEY-HIpUC20csSCGfC0BloscO4fOiqOhLbLRVxz94G2tGJe5sbcOuN1iec4kS2tNpJ3rAu94Rndbpb2K8i9RfV5VisfLh3Mo0-un5i6LhJ2MzRU5qY6J3VgY-Qn8NdeIpKTefxcMQf57_GfpHaU876hp9euwQSr9qCVzX5GuxR8G43arKCz1sPZK56yr-J6oDrqq&attredirects=0

I am attaching the pdf but sometimes that doesn't work.

Bob

Al_Service

Thanks, but that one is only for 2psi.