Need help understanding my system... Loonnggg post...

drtom

Okay, here goes.

Below I have attached a diagram of my system. I have only included the supply lines and radiators for the sake of simplicity. I have also taken some photographs to show examples of the system. The photos are labeled to match the diagram.



I have a two pipe system with air vents and without any traps. I am trying to figure out the best way to optimize it. It appears to have two mains, but they look like they are attached to the returns instead of the supply (see attached pictures of boiler and near pipes).



Radiator number 6 (see attached diagram) is a single pipe radiator that comes off of a supply line and takes a long time to get warm. I think the reason why is because radiator number 10 is in the upstairs bathroom and has a huge vent. Number 10 is the 1st one to get hot and I think it must be creating a vacuum that prevents number 6 from heating up until the vent closes.



Radiator number 2 is slow to get warm. I have the Balancing Steam Systems chart and I plan on using it to replace my vents.



The house heats up pretty well, but the water level at the boiler fluctuates a lot. When cold, I keep it filled almost to the top of the glass, and when the house is fully heated on a cold evening (outside temp 35 degrees F) the water level is almost at the bottom of the glass. I have also noticed a fair amount of surging in the glass while the boiler is getting warmed up.



I plan on purchasing the book "Greening Steam Heat" to try and minimize the costs of running the system, as it seems like I am using too much fuel right now. Last month my heating cost was $150 for natural gas. I set the heat to 60 at night and 65 during the day. It was a very mild month in terms of outside temp.



Please feel free to give me any insights you may have. All input is very welcome.

drtom

Diagram

drtom

More Pictures



Radiator #8





Radiator #7





Radiator #6





Radiator #2





Radiator #1

















Are these the "Mains"?

nicholas bonham-carter

loonnggg on post-short on main venting

the only main vent i can see appears too small. are there others?

if you have no traps, then the pressure should be low as already noted, and the floor is still nice--nbc

Jamie Hall

This is one OLD puppy!

The original two pipe steam... which didn't have traps, and did have vents, and had very confused steam... but did work, just fine.



The radiator vents are critical on these things.  Balancing them is the real trick, since all the radiator valves must be fully open for the system to work.  If you have a radiator which is getting hot too fast, and one nearby being slow, you can either slow down the fast one (number 10) by dialing its vent back (if it is adjustable) or by putting on a smaller vent, or speed up the other one (number 6) with a larger vent or dialing it up -- or better yet, do both.  It's not so much that number 10 is creating a vacuum -- it's just that it's easier for the steam to go there than somewhere else.



As nbc notes, main venting always helps...

nicholas bonham-carter

balancing a 2-pipe system

i would try the inlet valves for balancing, and i must say that main vents are critical in most cases.

since i do not have 2-pipe steam myself, i don't always know whether such a system has been "kludged" by the addition of radiator vents, or whether they were designed into the system at the start.

even so get the air out of the mains properly, or freeze while throwing extra money at the fuel co.--nbc

Oak Park Electric

Maybe it's a ...

Hmmm....



Two pipes, two valves, one a smaller pipe size, air vents and no traps.  Does anyone think it is the rare "two pipe air vent system"?  Look here   http://www.heatinghelp.com/article/11/Hot-Tech-Tips/280/Two-Pipe-Air-Vent-Steam-Heating  for more on this.  If it is, then you have an ancient oddball that was installed before man discovered radiator traps.  This type of system was the missing link between one pipe and "regular" two pipe ( with traps and no rad vents ) .  Like Jamie says, balance your rad vents or use adjustable ones to get it right.  A radiator with a big vent will get steam before the others.  Also you should have a pressure gauge on the boiler, there probably used to be one where the plug is in that tee by the pressuretrol.  Code requires a 0 to 30 PSI gauge, but put another tee in there and add a low pressure gauge too.  This one will show you the real pressure in the system, which should be so low that the 30 PSI  gauge won't even move.  Get a backflow preventer ( not a check valve ) on the water fill pipe,  and replace the safety valve discharge with copper that goes down to about 8" from the floor.  That mud on the side of the boiler makes me wonder if it's just as dirty inside.  This could be one reason for the surging.  Make sure the LWCO works, and blow it down periodically.

drtom

Dealing with the main venting...

This system is obviously not typical, which is why I am totally unsure how to handle venting the mains. The current "main" vents appear to be attached to the returns, not the supply. Does this make any sense?

Jamie Hall

I do indeed

think that this is one of the old old two pipe systems, as Oak Park says, before man discovered traps.  Do take a look at the link in Oak Park's post for how these things were set up!



As to where the main vents are on one of these things, it really doesn't matter much whether they were on the mains or the "returns" -- the idea is to get the air out of the piping when the boiler fires.  Having them on the mains would be a little bettter, but think about it: the boiler fires, and the tendency is for the steam to head out the mains.  Pushing the air in front of it.  Then through the radiator -- both valves being wide open, please, they aren't meant for throttling! -- and then into the "returns".  So a main vent on a return will see air, and vent it.  Just not quite as fast as a vent on a main.  So what would I do?  If the vents on the returns are working (actually venting -- which can be a little hard to tell) I'd leave them be and not worry about it.



The surging might suggest that the boiler could use a skimming; it could almost surely use a blow down.  It really shouldn't surge that much.  The drop in water level when the system is operating suggests that one or more of the returns, after they go below the water line, may be somewhat plugged and slow to let the water back.  Depending on how the thing was piped, it may or may not be easy to flush the returns.  On the other hand, the drop could indicate excessive pressure, with water backing out of the boiler and finding various places to lurk in the mains and returns.  I'd check the pressure first.  Should never be more than 1.5 to 2 psi...

BobC

vents

One of your pictures shows two vents where the returns turn down to the boiler return. that has worked for some 80 years but  todays boilers build steam a lot faster than the old coal boilers so venting is more important. Figure out the volume of the piping feeding those returns and put enough venting capacity on them to allow the air to completely vent in a few minutes.



Looking at your diagram it looks like you have some long runs so the venting has to be increased by a substantial amount. You may need more venting but I would start with a Gorton #2 vent on each return and see how it goes. Are those vents screwed into a 3/4" fitting? You present vents are probably 0,1 to 0.2 cfm, the Gorton #2 is 1.75cfm (@2 oz); you can always add more venting later if you have to.



Bob

TomM

looooong reply

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I too, am one of the lucky and brave souls with a two pipe air vent system. 

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The major problem with balancing (if you have dry returns) is that steam will go through one radiator from the inlet to the outlet, and into another radiator through its outlet, effectively having steam coming into a radiator from both directions! 

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Venting is crucial in this case, (well, its crucial in any case) because you have twice the air volume than a one pipe system, but it acts like a one pipe system, only with two pipes.  Two pipes is twice the fun.  But would three pipes only be 50% more fun?

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anyway, you should really post a diagram including your return lines.  I think your diagram only shows one pipe per radiator.  Also, make sure your rad vents are vertical, some are cocked to the side.  I am very surprised that nobody mentioned this yet.  (well, maybe they did, damn bifocals)

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(Side question:  whats the circa date for two pipe air vent systems?  i've been trying to date my system for a while, to no avail.   my house was built in 1875, but the steam system was put in later.) 

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Also, i would think that if #10 was the first to heat up, #6 would be the second to heat.  Maybe check your pipe pitch and pipe capacity on the #6 one pipe rad.   You mentioned 'vacuum', does the vent suck air in and out while heating?  Also make sure no vents are staying open.  Some look pretty old.   Dole's? 

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Lastly- get the books.  you will see 10x return on investment.

Steamhead

It's definitely 2-pipe air-vent

with some nice looking radiators!



When we're talking about returns, it's important to distinguish between returns that handle condensate only from the steam mains, and those that handle condensate from the radiators. The former can be vented if that's the best place to install vents for the steam mains, but the latter must NEVER be vented. The vents on the rads are all that's needed for the return side.



I'll go further and say this system should never be operated at more than 1 PSI. That's Vaporstat territory. This will minimize the amount of steam going into the return piping.