vapor system conversion problems

steamfitter

I'm trying to help out a friend who has an old home with a two-pipe steam system that has a lot of issues. I think this system was originally a Hutchison System." The LAOSH Companion has a drawing and explanation of this vapor system which included packless graduating valve and union elbows on the returns. There are no traps on the rads and the union elbows are not the type with a ball or baffle; not even a water seal. This system worked with a trap-receiver and damper regulator combination in the boiler room.

Currently it has two- 2" supply mains going around the basement and then dropping into a wet return which is about 4" under the boiler water line. No main vents. The returns wrap around the basement together with the supply as a dry return and then there's a Dole main vent before it too drops down into a wet return. Right before it connects into the wet return there is a swing check valve. The wet return circles around the basement and then connects to the hartford loop at the boiler. There is approx. 46" between the end of the supply main and the boiler water line and maybe a little less space between the end of the dry return and the boiler water line.

The rads are huge old column type with a 1/2" supply graduating valve on top and a 1/2" union elbow on the bottom return. Both on the same side of the rad.

There are near boiler piping problems that I won't get into right now because this is getting long. The boiler is running constantly and not building much pressure. The pressuretrol is set to come on at 1 lb. and turn off at 3 lb. Some rads are not heating up at all and most are only partially heating up. Those that are partially heating up seem to get hot on the top, while the return elbow feels cool. One rad in the hallway only gets hot in the first couple of sections.

There are a couple of small relatively modern rads with a regular rad valve and thermostatic traps that are completely cold.

I'm thinking those rads are completely airbound and the traps may be broken in the closed position. I thought that a main vent at the end of each supply main would help. Also replacing the union elbows with rad traps and removing the check valves on the return drips would help. However I'm not so sure the air would leave the huge rads properly because of the rad valve and traps are only 1/2" and there on the same side. I was thinking of drilling and tapping the opposite side of the rads and putting in air vents. Does this make sense?

I know I have to fix the near boiler piping because they capped one outlet on the boiler and reduced the other from 3" to 2." I intend to bring the 2- 3" lines to a full size header with swing joint elbows and use two 3" x 2" tees for the supply mains. I will also drop into the equalizer with a full 3" and reduce on the vertical pipe to the existing 1 1/2" equalizer.

I took apart one of the rads and took a peek inside the union elbow to see if there was any unique trapping type of fitting. The only thing I saw was a very small piece inside that may have possibly been a stopper for a ball that may have disintegrated by now or may have been removed. Then again the old Hutchison system states that there was no trap on the individual rads.

I am worried about the supply and return on the same side. Would the air get out ok? Is there something I'm missing here? I wouldn't want to do all of this work and find out that I have to replace the rads or redo all the piping. I believe the branch piping is small because of the vacuum system. But I figure that the rads are grossly over-sized and the smaller piping may be ok. Any thoughts on that theory?

I appreciate any help on this very old system that probably hasn't worked right for a long long time. The owner has only been in the house a few years. The boiler is pretty new (2009). It is in the neighborhood of 250,00 Btu and runs on natural gas. Thanks for your help.

nicholas bonham-carter

old hutchison system

when you say that the boiler is running constantly, and not building much pressure, that makes me wonder where the steam is going. these old systems need only a few ounces of pressure, to work properly, a pressuretrol is so inaccurate, that without a good gauge, there is no way to tell what the pressure is.

possibly, in the absence of traps, the radiator inlet valves are graduated to let only a tiny bit of steam in which can be completely condensed.

if the air is unable to get out, then i would expect short-cycling.

this is time to post some pictures of the rads and valves, as well as a diagram/layout of the supplies and returns so we can see how the steam gets up to the rads, and the air gets out.--nbc

moneypitfeeder

whew

Where to start, when there are so many issues...Well first things first, I'd be looking for a good deal on a vaporstat and a low psi gauge. You'll need to get the pressure down if you can, and its helpful to have a gauge to tell if your getting there. Start looking for a good place to break your mains near the end so that you can get some main vents added. Having the supply/return on the same side is fine, and rather than break every return elbow (and possibly change the pitch/height of the return piping by doing so) I would start researching orifice plates for the supply side. (give tunstall a call) I would imagine they are more cost effective too, and it looks like your friend is already going to be investing a good bit in his system. I wouldn't worry yet about the distribution pipe sizes, it will probably be fine, my old 2 pipe vapor system distribution pipes aren't that large and they work just fine. Welcome aboard!

Jamie Hall

That steam has to be going somewhere...

as nbc says, though, the question is where?



But before we even get there -- how is the boiler size vs. the total installed EDR?  It will do you no harm to check that, to make sure that the boiler is big enough to handle the load.  If it isn't, you'll never get pressure -- and never get warm.



Second, are the steam mains all insulated?  If not, they should be, and it's not a tough job.



Third, as moneypitfeeder notes, it's time to put a low pressure gauge and a vapourstat on that system; the Hutchison -- and any other system depending on graduated valves or orifices -- works very poorly indeed on any pressure higher than say 12 ounces per square inch.  Not that you are there yet, but hopefully you will be.



Fourth, check your dry return.  Nowhere should it be any more than warm.  If it's hot somewhere, you could be getting steam into it through a bad valve or one which someone replaced or otherwise altered the setting on; that won't help.  While you are at it, check the pitch on it.  It must be pitched to drain everywhere.  If there is anywhere where a water pocket could form, that will cut off the flow of air in it, which will cut off steam to the radiators upstream of the pocket.



Are the steam mains connected to the dry returns, for instance by a crossover trap?  If not, vents on the steam mains are probably a good idea.



The swing check on the dry return where it connects doesn't belong; you can probably leave it, at least for the moment, but if the pressures are correct it is unneeded.



Don't even think about replacing the graduated radiator valves and union elbows.  If the valves are properly adjusted, the radiators will get hot almost all the way to the bottom, and all the way across, but ONLY after the boiler has been running for quite a while -- an hour or two.  The idea is that the valve lets in just as much steam as the radiator can condense and no more -- and if the system is adjusted properly, such an arrangement is absolutely goof proof.  The radiators aren't meant to get hot all the way on a normal cycle -- which, however, brings us back to the boiler running constantly.



Let's worry about the two modern radiators later...



If it really is running constantly -- 24/7 -- and the radiators aren't hot and pressure isn't building it is either seriously undersized -- or you are losing steam somewhere.

gerry gill

before doing anything

else.. my first trouble shooting measure would be to remove the main vent from the return leaving just an open pipe and turning on the system to see how things heat and if steam is appearing where the vent goes..you cannot leave it like this..you must either put back the vent, or a new vent, or a group of vents that equal the capacity of the open pipe..this is an experiment to see if you had venting that equalled the capacity of an open pipe how does the system heat..i would do this test before doing anything else..

steamfitter

old hutchison system

I'm having trouble sending the pictures through attachments. Not too computer savy! The LAOSH Companion has the system on pages 5 & 6. The rad supply valve is a graduating type with a numbered dial on the top and a lever handle. It looks just like the fig.2 in the book. The old system used a trap-receiver along with a vent to the chimney. The piping plan is very similar to the one in the book, less the old boiler room specialty items. There are two- 2" supply mains, one for each half of the home. The mains run 2" all around and then drip into the wet return on the other side of the bsmt. opposite the boiler room. 

I just don't understand how this system can begin to work without main vents on the supply. If I were to install supply main vents and change the pressuretrol to a vaporstat do you think that would help? I would change the gauge to one which reads ounces of steam. I know the near boiler piping has to be redone. They capped one of the two outlets on the steam supply and they bushed the outlet they piped from 3" to 2."  I plan on repiping using both outlets full size into a 3" header and tying in the two- 2" mains that feed both sides of the house with 3x2 tees and then drop down to the equalizer. 

I have to find a chart which can give me EDR of old two column type rads. I used to have one but can't find it. Would you know a website where I can get such a chart? Not sure but I think my friend said his two story home, not incl. bsmt. was around 2700 sq. ft. There are roughly 8 huge rads and a couple of really small ones with the traps on them. I think the boiler is around 250,000 Btus. I have to double check all of that.

I believe they said one of the valves may not be working. How would I replace a rad valve that's obsolete?

Just thinking: can this type of system be converted to one where therm. traps and non-electric therm. rad valves are installed? The rads are tremendous but the connections are all 1/2 in.

  

Can this system still operate as a vapor system by using main air vents? I'm guessing changing the rad valves and installing thermostatic rad traps would not be a good idea at this point?

steamfitter

old hutch sys

Posted a response to nbc. I appreciate all of the great help you guys are giving me! I was wondering if you have seen a vapor system like this operate with just a return main vent at the end of each of the two dry return mains. I'm thinking the supply mains need a vent and the boiler header needs to increase to the outlet size on the boiler (3").

Will have to check the EDR on all of the rads and the boiler capacity.

Is it possible to vent a system like this too much?

There was one rad that only got hot in the first two sections. It was in the hallway. Most of the other rads got hot mostly on top, but through almost all of the sections after about an hour.

What about the idea of installing therm. rad. valves and traps? Most of the supply braches seem to be 1" or 3/4" and then reduced to 1/2" before it went through the floor.The supply and returns are on the same side of the rads. Would that effect the operation?

Thanks again!

Jamie Hall

A few responses...

I was wondering if you have seen a vapor system like this operate with just a return main vent at the end of each of the two dry return mains.

Yes.  In fact, many vapour systems have the vent(s) only at the boiler end of the dry return(s).  The steam mains vent via crossover traps into the dry returns.

I'm thinking the supply mains need a vent

not necessarily...

and the boiler header needs to increase to the outlet size on the boiler (3").

Probably.  You should check the manufacturer's near boiler piping diagrams -- remember that they are minimum.



Is it possible to vent a system like this too much?

Not really -- but it may not be worth the trouble and effort.  That said, if the pressure compensating device(s) or other fancier contraptions used on some vapour systems are still there and working, you need to use the same style of venting that was intended (well, not necessarily vacuum vents -- but at least the same locataions).



There was one rad that only got hot in the first two sections. It was in the hallway. Most of the other rads got hot mostly on top, but through almost all of the sections after about an hour.

That doesn't sound too far off.  As said in an earlier post, double check the EDR vs. the installed radiaton -- but remember that the radiators aren't meant to get all hot, except for long run times.



What about the idea of installing therm. rad. valves and traps? Most of the supply braches seem to be 1" or 3/4" and then reduced to 1/2" before it went through the floor.The supply and returns are on the same side of the rads. Would that effect the operation?

I would consider TRVs only -- ONLY -- if you have some rooms which are seriously too warm.  Otherwise, when they close the boiler winds up oversized by that amount, and that can cause problems.

As to traps, why on earth add a gadget which has moving parts and is sure to fail sometime, sooner or later, when the original system does the job just fine, thank you, by controlling the pressure and flow to the individual radiators with the valves or orifices which will last forever?  Don't add traps; you don't need them.

steamfitter

Thanks for your helpful response

I have to get insulation on as much of the supply piping as possible. There is none! Going to add up the EDR. Should I then multiply by 1.33 for the pick-up factor? I read somewhere that some old systems should use a higher multiplier, like 1.50, to calculate the pick-up factor. The boiler is rated for 240,000 Btus.

There are no crossover traps from the supply to the return mains. The dry return mains ( two- 1-1/4 in., one for each side of the house) have a vent before dropping into one common wet return( I think it's 1-1/2 in.). I was planning on venting the two - 2 inch supply mains, only after doing the vent test on the existing dry return main vents. I was planning on adding vents on the returns, if needed, first. I am wondering now that you mention crossover traps, if that would be better for the supply mains.

The manufacturer's near boiler piping calls for 2 1/2"  out of the boiler to the header when using both outlets and 3" out of the boiler when using one outlet. I think, because they are minimums, I'll go with both outlets, the full 3" and tee them into a 3" header. The vaporstat has to replace the pressuretrol and the low pressure gauge has to be installed. A supply house guy said that the town codes require you to leave the standard 0 - 30 psi gauge and you would have to install the other gauge elsewhere. Don't understand that one.???

Have to take a close look at all the pitch. I noticed the hartford loop has a larger than close nipple in it. Do you think that's an issue? I don't hear any hammer down there, but then again there's not much pressure yet.

Well I will let you know how it goes. Need to do a bit of work for now. I want to thank you kindly again for all your help. 

Jamie Hall

More replies...

have to get insulation on as much of the supply piping as possible.

That will make a big difference...

Going to add up the EDR. Should I then multiply by 1.33 for the pick-up factor? I read somewhere that some old systems should use a higher multiplier, like 1.50, to calculate the pick-up factor. The boiler is rated for 240,000 Btus.

If you are looking at the EDR rating of the boiler, the pickup is already in there.  If you convert EDR to BTU, and compare that to the boiler BTU, you do need the pickup factor.  I personally don't think that the 1.5 factor is needed, unless the mains are huge or there is a lot of uninsulated pipe.  But that's my opinion.

 

There are no crossover traps from the supply to the return mains. The dry return mains ( two- 1-1/4 in., one for each side of the house) have a vent before dropping into one common wet return( I think it's 1-1/2 in.). I was planning on venting the two - 2 inch supply mains, only after doing the vent test on the existing dry return main vents. I was planning on adding vents on the returns, if needed, first. I am wondering now that you mention crossover traps, if that would be better for the supply mains.

Strongly suggests that the original system was venting through the radiators -- which isn't really the best thing now (it worked in the old days with coal, as the boiler built steam much more slowly).  It's probably going to be easiest to add main vents to the steam mains, at the ends -- that will get you more even heat quicker.



The manufacturer's near boiler piping calls for 2 1/2" out of the boiler to the header when using both outlets and 3" out of the boiler when using one outlet. I think, because they are minimums, I'll go with both outlets, the full 3" and tee them into a 3" header.

Sounds like a plan...

The vaporstat has to replace the pressuretrol and the low pressure gauge has to be installed. A supply house guy said that the town codes require you to leave the standard 0 - 30 psi gauge and you would have to install the other gauge elsewhere. Don't understand that one.???

The code requirement (and most insurance companies, too) is that there must be at least one pressure gauge on the system which goes to twice the pressure of the pressure relief valve.  This is protection in case the pressuretrols/vapourstat don't work, or somebody messed up the wiriing.  My own preference on these things is to keep the original gauge and pressuretrol, set at say 5 psi, and put a separate pigtail and T arrangement to mount the vapourstat and the low pressure gauge.  Then wire the pressuretrol and vapourstat in series.  But then I always was a belt and suspenders kind of guy.



Have to take a close look at all the pitch. I noticed the hartford loop has a larger than close nipple in it. Do you think that's an issue? I don't hear any hammer down there, but then again there's not much pressure yet.

It's nice if the Hartford loop is a close nipple, but so long as it isn't hammering and isn't too long (like feet) I'd leave it be.  If it ain't broke...