Venting converted two pipe vacuum system

Onepipe

So, I have a house that I am pretty sure was a coal fired steam vacuum system originally. Some one installed a new boiler 5 years ago and the current customer who is new to the home called me to see if I could help balance the system. Currently the main floor gets warmer than the rest of the house and especially one side of the main floor. What I have found is that the boiler has two mains that run the perimeter of the basement and risers take off and feed each radiator. it is a two pipe system without traps and there are adjustable supply valves at each radiator (pic included). The steam then leaves the radiator and enters a common dry return which have a NO.882 ideal VAC VENT just before the return drops to a wet return at the boiler. During operation the main vent hisses like
crazy and once the short side of the basement loop is full of steam the 882 shuts off leaving air in the remaining larger half of the system. Here is what I would like to do:
1: Master vent the supply mains in the basement so that I can get the steam out to the end of the mains asap.
2: split the dry return at the boiler so that both sides of the basement have their own return pipes which will be vented individually.

My question is do I need to have a main vent that will allow for a vacuum to be pulled on the off cycle or can I use something like a bigmouth on the end of my returns?

Steamhead

That's a Richardson Vapor system. The elbows on the radiator returns look ordinary, but they have internal components that are supposed to keep steam from entering the dry returns. Post some pics of the return connections to be sure someone hasn't changed them. See chapter 15 of @DanHolohan "s "The Lost Art of Steam Heating" for an in-depth discussion of this.

Master venting the steam mains will help, but if you keep the pressure under control, the steam will not get into the returns. The boiler should have a Vaporstat instead of a Pressuretrol. Set it to cut out at 6 ounces or so.

That vent on the dry return is way too small. A vent that's too small will require more pressure to move the air out, and will hiss like that too. Use a Gorton #2.

And last but not least- that boiler was not installed correctly. It looks like they used 2-inch pipe where it should have been 2-1/2", and they only used one steam outlet when they should have used both. This causes wet steam and inefficient operation. Though the brand name is Bryant, it was actually made by Dunkirk, and these Dunkirk steamers are very sensitive to improper piping.

Where are you located?

Onepipe

I am located in Michigan, grosse point to be exact. We have a lot of one pipe steam around here but this is the first that I have came across a system like this. I did notice that they only used one supply tap and have already talked to the customer about re piping the header. When I walked in the the the pressure patrol is a cut-in type that was set at 3lb with a 1lb differential. I brought it down to a 1/2”lb cut in with a 1 1/2” cut out for the time being. I will talk to them about a vapor stat. I will send pics of the elbows tomorrow. There is one radiator (cast iron baseboard type) that is a small steam trap. I am assuming that is ok to have in the system. The inlet valve on that radiator looks to be a standard steam valve you see on a two pipe steam system. 

Would you say that I need to split the common dry return and put two Gordon #2 vents on the end of the run. If you look at the pic with the 882 I would break the dry return where it comes into the tee just before the vertical drop and put a vent and vertical tie in to the wet return. That pipe has 3/4’s of the house that needs to be vented through it. The supply mains are separate but the return is tied together. My fear is that I’m going to get steam in the return from the shorter side and it will shut the vent off ( that’s what’s happening now.) and then the remaining cold radiators are air locked. Steamhead, you mention that there should not be steam in the dry returns but they sure get hot like they have steam so something must be leaking I’m guessing.

that said the boiler is very quiet, that I cannot figure out either with the one pipe header and lack of venting. Thanks.

also forgot to mention there is a condo safe drop and full perimeter wet return that comes off of both steam mains. That’s what the fry return ties into prior to the heartford loop.

Onepipe

Here is a pic of the return 90. The customer was able to send me a pic. 

Onepipe

Just looked at chapter 15…..loops like I have a lot of reading to do! Lol

mattmia2

A low pressure gauge will really help diagnose here too(like 1-3 psig). The system keeps steam out of the returns by those metering valves regulating the amount of steam that can enter a radiator to the amount that the radiator can condense. The amount of steam the valve allows through is proportional to the pressure so keeping the main pressure very low is critical to making the system function properly. If steam gets in to the return because the pressure is too high, the valves are set incorrectly or there isn't a vapor valve on the inlet to the radiator(the one with the steam trap is probably ok with a standard valve), the steam in the return will close the vent before some of the system has vented so that part of the system will never heat completely. Inadequate venting in the returns can also cause it to build pressure. You need adequate venting on the returns but you shouldn't need to split anything, concentrate on getting the near boiler piping right.

If the boiler is oversized so it builds pressure, a vaprostat is critical to making the system work properly.

Having the mains tee together and connect in to the header and having water likely thrown up in to the mains by the near boiler piping likely also aren't helping balancing.

Jamie Hall

It is a vapour system as has been said. You need to get the pressure low enough -- as I think @Steamhead said never ever of 6 OUNCES per square inch for the cutout. What you now have is still way too high.

The other thing is that once you get the pressure where it belongs, you will not have steam in the dry returns. You want the dry returns to tie together above the water line -- don't split the as you enquired -- and you need generous main venting on the dry returns where they join, before they drop to the wet return.

Now a question -- perhaps I missed it. How do the steam mains connect to the dry returns, if they do? in many vapour systems - but not all -- there will be crossover traps on the steam mains which allow air in the steam mains to get into the dry returns. If they are there, they function as the main vents for the steam mains and you don't need any others.

Onepipe

Jamie, 
The steam mains only connect through the radiators to the dry returns. There is a drop to a wet return at the end of each main that runs the perimeter of the basement back to the heartford. I can double check again but I’m 90% sure there is not a cross over pipe.  

Jamie Hall

Actually that will probably work pretty well -- although the most distant radiators may be a little slow.

Steamhead

Onepipe said:

Here is a pic of the return 90. The customer was able to send me a pic. 

Yup, that's a Richardson.

Steamhead

Onepipe said:

Jamie, 
The steam mains only connect through the radiators to the dry returns. There is a drop to a wet return at the end of each main that runs the perimeter of the basement back to the heartford. I can double check again but I’m 90% sure there is not a cross over pipe.  

Not having a vent here was fine in the Coal Era, but not with gas. Coal burned all day so once all the radiators got hot, they stayed hot.

I'm sure the insulation on the main is asbestos- don't touch it! You could cut the horizontal part of the drip (1-1/4"?) and put in a tee for a vent.

How long are the steam mains, and what pipe size?

Onepipe

So yes I was hoping that master venting both of the mains would help out the system. The mains are two sizes. 2-1/2” for the long run @ 50’ and the short main is 2” @ 40’ and the drip at the end of each main is 1-1/4”. I have an an abandoned tee with a plug in it on the short main about 20” from the end of the run from a kitchen Reno that would be perfect to use for my vent. The longer main in the pic yes does have asbestos. 

Onepipe

@Steamhead so……I have not had all my coffee yet. Ha! I just caught what you said. So I can tap in on this 1-1/4” drip for my main? Just bring it up as high as I can above the header? I sketched  on the pic as reference. Thanks

Mad Dog_2

Steamer..what year did Boynton join or bail out?  Mad Dog 🐕 

Jamie Hall

exactly. So long as the vent tapping is well above the boiler water line, that will work just fine. And help -- perhaps dramatically.

Onepipe

OK, First off I cannot thank all of you for the help so far as I am learning a ton with this job. I have verified that all of the radiators still have the correct Richardson return 90's. two of the radiators have had their supply valves replaced but they look to be modern vapor system valves and not normal steam valves. So here is where I am at:

1. I am going to dry out my steam and re-pipe the header with a double drop header that has 2.5" mains off the boiler tabs and a 3" supply to the Tee that feeds the two supply mains.
2. Install a vaporstat and low pressure gauge with my cut out at 6oz
3.Master vent the end of the supply mains. I might be able to use a Gordon #1 on the shorter 2" main but for sure the longer 2.5" main will get a Gordon #2.
4. Remove the #882 vac vent on the dry return and replace it with two Gordon #2's (keeping the dry return tied together)
5. Verify all pipe pitch and hanger placements for correct condensate drain.

I think that's going to get me into a pretty good position to start to work through the radiators and valves as I know that they will need adjustment and servicing based on age. Please let me know if I have got off in left field some where with my list.

OK so next round of questions:
I got my laser in the basement today to start looking at pitch and I discovered that some of my wet return is now above my boiler water line....I am guessing this happened during the the installation of the new boiler. I have provided a picture that shows' the dry return (red arrow on the top of the pic that does not enter the wet return until just before the Hartford) and the supply main drip leg that drops down to what I think should be a wet return that runs the perimeter of the basement back to the boiler. I have a lower red arrow in the pic that shows a rolled 45 that actually raises the pipe which would cause condensate to puddle if it was a dry return. SO... am I correct this should be a wet return and I need to raise the boiler when I re pipe the manifold?

Second question: is there a proper way to adjust these Richardson radiator supply valves once I get the pressure under control? i know that I am shooting to have them supply 80% of the radiators EDR capacity so that they don't allow steam to enter the dry return but I not sure how to do that other than by the old trial and error approach.

Last question: Should these Richardson radiators be pitched towards the return drain pipe or sit level?

Thanks for all the help!

Jamie Hall

Sounds like you are well on your way there!

The wet return which isn't any more... oh dear. Is there a handy dandy way to lower it? They don't usually cause trouble in a vapour system, but... it would be nice. On the other hand, wet returns don't care whether they go or down or whatever, so long as they stay wet so that odd 45 you note shouldn't be a problem.

The radiators should be pitched to the return, but -- unlike one pipe -- it doesn't have to be much. What they shouldn't be is pitched towards the inlet.

And is there a good way to adjust the valves? Um... not really. Trial and error, changing one valve is likely to change the way other radiators on the same main operate. And it's usually easier to slow down an overenthusiastic radiator than it is to speed up a laggard. Main thing is to get the heat you want, where you want it.

mattmia2

Onepipe said:

1. I am going to dry out my steam and re-pipe the header with a double drop header that has 2.5" mains off the boiler tabs and a 3" supply to the Tee that feeds the two supply mains.

If you're going to re-pipe the near boiler piping then get rid of the tee above and bring both mains in to the header separately, the tee could cause balance issue although it certainly isn't your biggest problem.

The return could either be lowered or you could create a false water line at the boiler. Are there multiple connections to the now dry return that could interfere with each other? If you don't need the water seal between connections you shouldn't need it to be full of water until the place where the returns connect together at the boiler when you can drop down to get a water seal.

Make sure the valves that have been replaced are metering type valves, if they are not you will need to put an orifice plate or steam trap on those radiators to keep the steam out of the returns.

Steam in the returns will keep other radiators from venting, both by closing vents prematurely and by blocking the flow of air out of other radiators. Your returns should never be steam hot.

I suspect the original documentation for the Richardson system or the valves had a setting for the valve based on EDR. There may be some Richardson documentation here somewhere.

It would be worth it to add up all the EDR and compare it to the boiler to see how well they match.

Onepipe

Jamie, Thanks for the info. The wet return is partial wet but at the far end of the system it raises above the water line. Currently it is not causing any issue but I would like to take care of it especially because its that 45 area that is now dry. I thought about lowering the wet return pipe but there are a few drops that i would have to extend. I figured if I was rebuilding the manifold anyways the easiest thing to do at that point would be to raise the boiler a bit and adjust the Hartford, but both are an option as the return pipe is 100% exposed. I'm not sure if the "A" dimension comes into play on a vapor system with the low pressures but I have plenty of height. Do you know a good supplier for new radiator vapor supply valves incase I need one?

mattmia2

New vapor valves are no longer manufactured. I think Tunstall has rebuild kits for some valves. NOS Hoffman vapor valves seem to be available on ebay(though searching by part number seems to yield more than by vapor valve).

Onepipe

An operational question. Once the system is running correctly I should not have steam in the dry return, so that said the pipe at my return vents (end of run just before it drops to the wet) should be warm from condinsate passing through the pipe right? Not steam hot but not cold either. 

mattmia2

Correct. The condensate will make some of the returns warm or hot but not as hot as the mains that are full or steam.

In theory the returns of a 2 pipe system could be open to the atmosphere because there should never be any steam in them if the rest of the system is working properly.

tim smith

Tunstall does not have a rebuild kit for the vapor valves, per Woody. Too bad, I just finished rebuilding a bunch of Webster Sylphon valves with his rebuild kits. Great solution. Good luck.

Onepipe

Progress is going good on the Richardson  boiler system and have the return piping all re pitched and the vaporstat installed with a cut out of 6oz. The system is WAY quieter now. I’m about to re pipe the header and add my main vents. Before I do this work I wanted to verify my thoughts. Because my steam mains all have drip legs that tie into wet return at the end of the runs my thoughts are that the supply mains should be pitched to the returns not the boiler. Is that correct? See attached photo. Thanks for the help.

Jamie Hall

Correct on the pitch. Parallel flow of condensate is much preferred whenever possible!

Onepipe

Richardson system update:
The system is now running pretty good but the steam is taking a wile to get up to some of the upper radiators before the stat satisfies. I am going to be moving the stat as it’s in a poor location and also taking a few of the inlet valves apart for a rebuild as they are stuck in position. I am trying to keep the system under 6oz with out short cycling so as I have been thinking about it venting came to mind.

My question: can I add smaller main vents to the second floor risers (before the vapor valve) so that I can get steam to not only the end of each main but to each vapor valve roughly at the same time? 

My thoughts are if I do that I can then just adjust each valve as nessary to ensure no pressure drop, balance and keep my water seal. That way I’m not depending on that small bleeder hold in the Richardson elbow to vent all my air in the riser and let it only worry about the radiator once the steam is there. 

I have added main vents to both of the supply mains and the dry returns. Currently I have steam to the end of each main in a little over 5 min at an operating pressure under an 1/8 of a pound of pressure. It is a large house 3 story 3500sqft and the t stat is located in the dining room with a very large radiator at the beginning of the main. 

I have used this technique on one pipe systems and it have increased efficiency and control of heat 10 fold. 

Thanks for the help