Venting the risers in the front of my building?

years_of_steam

I live (for a long time) in a 5-story brownstone in Manhattan with a one pipe steam system, boiler in the back in the cellar. This year for some reason the radiators in the front, especially on the top floor, are not getting hot though put a new Gorton # 1 at the end of the main to the front in the cellar (about a 50 foot run); I've also changed all the air vents (varivalves). It seems to make a difference but not enough.



I brought in a plumber to look at putting air vents on the top floor front radiator feed before the radiator valves, and though it's a bit tight he says he can do it. He discourages me from trying to put them high up on the risers on the floor below (which are more accessible), says I'll get water from the return condensate and it will mark up my walls and ceiling. But he also says the air vents won't make any difference, I should just turn up the pressure a bit. It's currently set at 1 (I think, maybe a bit lower) with a differential of 1.5 (I think). He says he's happy to run a test for me by disconnecting a radiator on the top floor and firing the boiler on manual to see if the steam gets to the top floor any faster.



He's a new plumber to me though recommended highly by my neighbors. I'm looking for any comments/suggestions?

nicholas bonham-carter

what has changed ?

some thing is now different, and the system is out of balance. if anything, this may be caused by a clogged pigtail.allowing the pressure to shoot up out of control, rendering the vents inoperative. get an accurate low pressure gauge [gaugestore.com--0-3 psi]. you can heat this building cheaper, and better with 8 ounces or less.

that gorton #1 is small for a 50 foot run of probably 5 inch pipe, so put 2 gorton 2's on it to start.

as far as the risers go, you might try gorton d's on the top rads, and hoffman 40's on the intermediate floors.. remember: vent the mains at lightspeed, then the risers at moderate speed, and the radiators slowly.

check the thermostat for anticipation or setup as well.--nbc

years_of_steam

a bit more info

Thanks for getting back to me so fast! Actually I think the main is no more than 4" and maybe even 3", it is 11 inches diameter? Still 2 Gorton 2's? It's a pretty funky vent setup, apparently the only way there was room. I am putting a photo here.



Also, I may be wrong about the settings for the pressure. Here are a couple of photos of that, maybe you can tell me? Looks like it's set at just under 1 psi, with a differential of 8 oz? does that make sense? Can I tell if the pressure is shooting up just by watching the dial below when the boiler is making steam?



Are you saying try changing the vents on the radiators to other brands (rather than changing the setting on the varivalve) and not worrying about venting the riser? I was under the impression it is better to keep the same brand of vents throughout the system?



Once again, thanks for guiding me!

BobC

DO NOT INCREASE THE BOILER PRESSURE!

I would check the pigtail feeding the vaporstat to be sure it's not plugged and I would install an auxiliary 0-3PSI gauge so I could monitor the pressure.



That 50 ft long 11" circumference pipe is probably a 3' pipe and it has about 2.5 cu ft of air in it; that air has to be evacuated fast. A Gorton #1 is going to take 8-9 minutes and that just isn't fast enough. A Gorton #2 will do it in about 2.3 minutes, if space is a problem put in 3-4  Gorton #1's on an antler. Assuming the steam mains are a similar length, the venting on them should be about the same; if they are different lengths they should be proportional. You may actually need more but try that first.



the varivalves are very aggressive, i would dial them all down very low except for the ones at the top of the risers, I'd try setting those at a little below midway. That should help to vent the riser quickly and allow the other radiators to vent slowly. If that seems to work I'd move forward with adding vents to the pipe seeding the top radiators on the risors and then dial the vents on those radiators down. It will thake some experimentation to find the right mix.



DO NOT INCREASE THE BOILER PRESSURE, that will make everything worse. The varivalves don't have floats so you may get some water spitting out of them but if you keep them dialed down low you should be ok.



Bob

years_of_steam

followup questions

Thanks Bob for your reply also. Questions: Will the Gorton # 2 just fit in the same spot as the # 1 is now? are they the same size fitting?



And what is the dial that is just above the pigtail in the picture I sent? it's not the auxiliary guage you are talking about? Where would the auxiliary guage be installed?



Thanks again..

BobC

Big vent

The Gorton #2 is a large vent 6-7" tall and it has a 1/2" thread so you may need to reduce a 3/4" fitting to a 1/2". If that overhead pipe is to close just use a couple of elbows and short nipples to clear it. A good hardware store should have whatever you need. You can buy vents at pexsupply.com if you can't get them locally.



Your current gauge on the pigtail is a 0-30PSI and they are pretty much useless (but they are required) for seeing what is going on with low pressure steam. People usually use a "T" and a couple of short 1/4" nipples so they can mount a 0-3PSI gauge besides the Vaporstat (just make sure you kill the power before un-wiring anything).



Bob

years_of_steam

A bit further

Thanks Bob again. That explains what I am looking at when I check my boiler, and (I imagine) why the needle on that 0-30 guage does not budge when the boiler is firing ...... Mind you I am not doing this work myself, I will be getting a plumber to do it, but I do need to have a clear understanding for my conversations with him. And I may buy the parts just to simplify things.

years_of_steam

specific unanswered questions

Will removing a radiator on the top floor and then firing up the boiler, to see how fast the steam rises when that pipe is wide open, (of course ready to shut the valve as soon as the steam shows up) yield useful information about whether it will help to add a vent at that location (just before the radiator valve)?



And would the answer to that change depending on whether we have or have not yet put in the Gorton 2 on the main already? or does that make no difference to the test?



And lastly, if trying to put a vent up high in the building, is it a bad idea to put it on the riser in the floor below the top floor, and if it is OK to do, should it be near to the ceiling or can it be lower down? or is it much better to put it actually on the top floor at the feed line just before the radiator valve.... the only place on the top floor that we can reach.

nicholas bonham-carter

Open vent test

Generally you would do the open vent/valve test to see if there is a blockage, such as a sag in the supply line preventing the air from escaping. In your case, you want to speed up the air removal from the riser, and I believe that putting a large radiator vent on the radiator at the top of the riser, after slowing down the intermediate floor rad vents, will get the riser filled before the steam begins to go into each floors radiator. So you have minutes after firing, all the mains, and risers filled with steam, now ready to push against the greater resistance of the intermediate floors radiator vents.

You can never have too much venting on the mains. You can certainly calculate the volume of your pipes, and add in the capacity of the boiler steam chest, and arrive at the number of main vents you need; however my advice is to keep adding main vents on the menorah, until the back-pressure is below a couple of ounces. The calculations will give you an idea of how many to order first, and the back-pressure will tell you if you need more.--NBC

One more thought as I now see you mention the front of the building--do all the risers in the same way at the same time, with the switch to lower velocity radiator vents for the intermediate floors!

years_of_steam

So I understand...

And the low pressure gauge you recommend is what tells me the back pressure?

Thanks again

Dave in QCA

fighting radiators

First, I will say that I agree with everything that BobC and nbc have said regarding main venting and radiator venting.  Venting is likely the problem.  Especially, if the problems may have started when the varivalves were installed, or even when someone adjusted them.



In addition, I want to expand a little bit on over venting of radiators.  When radiators are over vented, it allows steam to wander freely into what ever radiators are the nearest to the main flow of steam as it comes roaring down the main upon start-up.  Steam is fickle, and which radiators become the favorites of the steam is hard to guess because it can be affected by so many things.  But, when radiators are over vented as they are with varivalves, the first few radiators to get steam will get too much and get it too fast.  Since the vents are so unrestricted, the air freely leaves the radiator to allow the radiator to quickly fill with steam.  A radiator that is not fully heated, but full of steam, will draw much more steam than what it is rated - way more than that 34% allowance.  It will act like a huge vacuum, sucking all the steam that it can for long enough time until the iron is fully heated, at which point the steam flow will slow down to the actual rating of the radiator.



But all that time that the greedy radiator (s) is sucking way more than its fair share of steam, there will not be enough to go around to the rest of the radiators on the playground.  The dilemma is to figure out if you will require vents at the tops of the risers to correct the problem, or simply slower radiator vents throughout the system, or even perhaps, both.



I would recommend making the main vent changes that have been suggested.  But, at the same time, or immediately, you can check to see what the effect is of slowing down the radiator venting by closing each and every one of those varivalves to their minimum position.  That position is not closed by any means and should provide enough venting for any radiator.  After you main vents have been improved, if you still have radiators that are slow to heat, you might adjust those to the half open position and see where that gets you.



Keep us posted!

years_of_steam

just to be clear

Thanks Dave, and while I am doing the testing do I leave the varivalves on the top floor wide open to (in effect) vent the risers?

Dave in QCA

As a Starting Point

You could do it either way, but I think as a baseline starting point, I would put ALL of the varivalve in the minimum position and see how it runs.  If the 3rd floor rads are a slow, then you could speed them up by opening those vents to 50% and then see what happens.  It will be mostly trial and error, but I would start with them all in the minimum position as a starting point.

years_of_steam

Feedback- big improvement already

Well the Gorton #2 and low pressure gauge have shipped to me already but not yet arrived, will arrive tomorrow and Monday. Thanks for the internet resources.



In the meantime I have closed down all the varivalves except on the top floor which I shut half way and may shut all the way tomorrow. Already quite a DRAMATIC IMPROVEMENT in most of the radiators (excuse my shouting, I am quite enthusiastic already) even without yet improving the venting of the long main.



Thanks to all and especially Dave for making the reasoning clear to me about the varivalves. I've been using them for years pretty happily but I'm happier now that I'm educated.



Looking back on it I'm speculating partly the problem this year started when my water level in the boiler was too high at the start of the season, I lowered it following advice on the Wall, but maybe before I did that it sent a lot of water up and messed up my vents? I think the water level was high because a plumber replaced a section of corroded return during the summer and when he refilled the boiler filled it too much? (My regular heating contractor twice had said that the high water level was not a problem so I sort of lost confidence in them....)



Anyway thanks to all, I'm really impressed with how closely you follow the questions. And thanks to Dan for writing the books and creating the Wall.

Jeff_44

For What it's worth,

I had the same issue with Vari Vents. I was having real balance problems even though I had two Gorton #2's on one main and 2 Hoffman 75's on the other. The Gorton's never closed at the end of the main and I thought I had too much venting. But...thanks to all the great folks here, I learned that the rads with Vari-vents were hogging most of the steam. The only way I could slow them down enough was to place them on the slowest setting and then put aluminum heating tape over the aperture. Now everything is nice and even and much better.

years_of_steam

Still need advice

Following your suggestions, I now have 2 Gorton 2's on the end of the long main (50 foot main, I think 3 inches though one consultant told me my mains are 2 inches); and I have a Gorton 1 at the top of the riser that's farthest from the boiler, just before gate valve for the radiator in that corner on the top floor. Most of the radiators are now heating pretty well, with the varivalves on the lowest setting. But one corner of the building, with the riser farthest from the boiler, is still slow and not hot in spite of the Gorton 1.



This is a five story building, built in 1900, so high ceilings. In the cellar, at the end of the long main, which goes down the center of the house, a branch goes off to each front corner of the building-- a 10 foot run in each direction. Then it goes vertical through the first four floors, supplying radiators on each floor, before getting to the top floor radiators. Say maybe another 50 feet vertical, through inch and a half risers.



That top radiator is still not getting very warm; and it's slow to start getting warm. The two radiators on the two floors below, on that same line, also are not getting very warm. Below that is an enormous radiator in the main entry hall.... it has a varivalve set to the lowest setting, and it does get warm. And below that is a small radiator in the lower entry that also gets somewhat warm. But that whole line is the last to heat of the 25 radiators in the building.



Would you put a Gorton 2 up there instead of the Gorton 1 I have? Or would you do something else?



Thanks in advance for your help.

BobC

Slow everything else down

The steam will take the path of least resistance so maybe the answer is to slow the other radiators down a bit so this last line gets a bigger share of the steam. A varivalve at minimum is still a big vent on lower floor radiators. Problem is with a building that size experimenting gets pricey.



For starters try slowing the venting on that giant radiator down by putting a Hoffman 40 or Gorton #4 on it and see what kind of difference that makes. That vertical riser has to be 40 ft long, how far from the main vents is the base of that riser? If it's a significant distance a vent near the base of that riser might help.



If that problem riser has 5 radiators on it then the other 20 Heatimers at their minimum setting are expelling 1.3cfm verses the the 0.33cfm of that Gorton #1 not counting the venting on those radiators so it might well be starved for steam.



Bob

years_of_steam

following up

I can easily put the Hoffman 40 on the giant radiator, will try to do that tomorrow. The vertical riser starts about 10 feet from the end of the long main.... it's actually not so easy to put a vent on it. Are you saying not to try to put a bigger vent at the top of that riser? that would be easy to do at this point.... thanks!

BobC

Try it

More venting at the top of that riser might help along with small vent on the huge radiator, if not start looking at closing down some of the other radiator venting, especially those on lower floors.



Bob

years_of_steam

Thanks

Certainly worth a try! And you're right about experimenting with lots of vents being a bit pricey.... but so far I'm well ahead with all the helpful expertise at no charge. Slowing down all the varivalves certainly was a big help already. And if I can take it one step at a time it should be manageable. Thanks, and I'll keep you posted.

nicholas bonham-carter

Rebalancing the system

By now you should have the low-pressure gauge on next to the pressuretrol.

Next get Hoffman 40's for all the radiators on the intermediate floors, with the remaining varivalves put on the top-set to their minimum settings.

As the boiler begins to make steam, you should see the gauge registering an ounce or so. If you don't see that, then put another gorton #2 on each antler, and verify the low back-pressure. When the mains have filled. And the main vents close, then the pressure may jump up to 3 ounces or so, which is the increased resistance of the air leaving the radiator vents.

With this venting scheme, the steam will not rise up in the closest riser, but will wait until all the horizontals in the basements are full of steam. Then all the risers will fill with steam at the same time, and steam will arrive at each radiator on a given floor at the same time.

Therefore Mrs. Smith's bedroom radiator will be at the same surface temperature to Mr. Jone's bedroom radiator, even though each is on a different riser.

The radiators on the top floor may need more venting, but my preference would be to use gorton d's.--NBC

years_of_steam

That's helpful too

I do have the low pressure gauge in hand, but it's not on the boiler yet because I don't have someone qualified to do it available yet. So far I've been working with a handyman-plumber who's willing do follow the diagrams for the venting piping without understanding the reasoning, but he doesn't work on the boiler itself. The boiler person I have at the moment disagrees with your (collective) advice altogether and says people on the internet don't understand NYC. He began to get a bit huffy. But as you explain to me, I will expand my search for someone qualified to install the low pressure gauge.



I will take your advice about the Hoffmans on the intermediate floors.



There is another wrinkle I haven't fully explained yet, which is that the boiler is actually in the very back of the house (which is a townhouse, 20 ft wide by 60 deep by five stories above the cellar; with a 14 by ten foot extension in the back that is three stories high) The radiators in the back of the house are served by mains and risers that are much closer to the boiler and only one of those back mains (to the extension) is vented. The riser closest to the boiler actually has a very very short main, and serves only two radiators, on the top two floors. I haven't been talking about them because they are getting hot but maybe they are taking too much steam too soon? Not sure how to deal with that....



I'm thinking for now, one step at a time, within the limits of my abilities and helpers. And see what I can do about the low pressure gauge.

nicholas bonham-carter

2nd gauge placement

Please see Rods excellent advice on low-pressure gauge location. All of us have learned to do as much of these modifications, as it take less time than waiting for the pro. The beginning of winter has more opportunities for shutting down the boiler for several trips to the hardware store/plumbing supply house.--NBC



http://www.heatinghelp.com/forum-thread/139950/How-to-properly-install-a-second-pressure-gauge

years_of_steam

Helpful suggestion

That's really helpful guidance and I still think putting that gauge on is beyond the range of me and my handyman, I will be looking for someone willing and able and will be looking over their shoulder as well...

years_of_steam

low pressure gauge

Well first of all a report ..... venting with the Hoffmans at the intermediate radiators immediately allowed all the lower floors to heat up much more completely. The top floor was still cold. Added more vents yesterday so now have 3 gorton 2's on the long mains, and 2 each on the top floor front risers. Turns out one of the two radiators was a giant cast iron, 8 bars across and 6 deep. I left the varivalve on that one half open, and put a hoffman 40 on the other smaller one. Seems to be helping a lot though I will check as the day goes on.



About to arrange to put the low pressure gauge on, can it share a pigtail with my existing 0-30 one? or does it need its own pigtail? As you can maybe see from my pictures above, the current 0-30 pressure gauge is between the boiler and the vaporstat.



What a help to have you folks!



I will also have some questions about the vaporstat.

years_of_steam

is my low pressure gauge reliable?

I now have this low pressure gauge installed.

http://www.valworx.com/product/low-pressure-gauge-0-3-psi-bm



The old pigtail was not clogged but the heating serviceman put the new gauge on with a new (brass) pigtail. He also commented that this was not a steam gauge and it would not be accurate. (?)



My Honeywell vaporstat is set to 1.5 psi with a differential of 10 oz. But what happens when the boiler runs is that it takes about 20-25 minutes to come up to .5 oz on the low pressure gauge from a cold start, 15 min or so on later cycles..... and then it takes about 3 minutes or so more to get up to 1.1 on the gauge, at which point the vaporstat trips and the boiler turns off. When the pressure is back at .5 on the gauge (in about a minute or two) the boiler goes back on. Then we are cycling back and forth in that pattern, down to .5 and back up to 1.1 every two or three minutes.



So if the gauge is right, I am operating at about a half pound to pound of pressure, when it is set this way. So what does it mean that the vaporstat is set at 1.5 with a differential of 10 oz?



Haven't been able to monitor how the radiators are filling yet, as I've been pretty much stuck in the basement, but will get a chance to do that tomorrow. All I can say right now is that if anything we have too much heat in the lower floors.

BobC

You should be ok

Looking at one of your pictures it seems the pigtail should be rotated 90 degrees so you cannot see the loop in the pigtail. The pigtail expands with heat and is probably throwing the vaporstat out of level and that changes the setpoint because of the mercury bulb. Take a picture of the current setup so we can see if it's still like that.



Operating from 0.5 to 1.1PSI should be fine, you could even dial it down a bit more. The absolute numbers are not important as long as you are operating at a low pressure.



As long as there is a pigtail between the low pressure gauge and the boiler it should be accurate and the pigtail will keep the gauge well below it's temperature rating. My 0-3 gauge just gets warm, never hot.



Bob

Dave in QCA

answers

The new gauge does not care what it is measuring.  Live steam would destroy it, but that is why you have a pigtail.  It will work just fine.



Regarding the vaporstat, remember that while these work well at low pressures they still may not be perfectly calibrated.  That is why you have a gauge.

The Main setting on the vaporstat is the cutout.  1.5 psi is when the switch turns the boiler off.  Remember that 1.5 psi in ounces is 24 oz.   A 10 ounce differential means that the pressure must drop 10 ounces (to 14 ounces) before the switch turns back on.   Remember, your gauge is in psi.  .5 psi = 8 ounces.



It sounds to me like you're vaporsat and gauge are both working just fine.  How is the system heating?

years_of_steam

how low can I run the pressure?

Thank you for your feedback! I think the pigtail is put on right, I'll send a picture in the morning. The lower part of the house is if anything overheated, it's a mild day and I have to run the boiler a long time to get the pressure even up to 8 oz. The radiators on the lower floors get very hot while the pressure on the gauge is reading .1 to .15 I'll track it more tomorrow. So my question is how low can I set the pressure? maybe I'll run the boiler a bit longer with a lower pressure?

years_of_steam

Upper floors data not available yet

I know that at one point today the top floor radiators were hot when the boiler had been running for 20 mins or so at it's top range of pressure.... about 18 oz on the gauge.... but I didn't have full access to data since when I was available the occupants were asleep....

nicholas bonham-carter

Checking the temperature

Get some wireless (Taylor) indoor/outdoor thermometers, and put the outdoor sensors in the colder apartments. Each should be able to monitor 3 sensors, and will show you the maximum, and minimum temperatures (even when the occupants are asleep!)--NBC

BobC

overheating

The overheating close to the boiler sounds like you have to vent those radiators more slowly so they will heat up slower. The Heatimer Varivalve is pretty slow at the minimum setting but with such a wide range i wonder if they all go down as low as we would like.



I'd suggest the Hoffman 40 but you might want to get a handful of Maid O Mist #4 vents (less cash) if you can find them, they are very slow and the nice thing is you can remove and drill out the orifice if you need a faster vent. Try them on one warm apartment and see how they compare to the Heatimers. If you can't get them locally look here   http://www.pexsupply.com/Jacobus



The fact the boiler takes a long time to raise pressure is good, steam can heat in ounces of pressure when it is setup well. I think we just have to rebalance a bit more so we slow the bottom floors and divert the steam to the cooler areas.



Bob

Dave in QCA

Heat timer is fast..........

The Heat Timer Varivalves are FAST.  In the full open position they are .66 cfm at 1 oz.  Compare this to these main vents, Gorton 1, which is .33 cfm, the Gorton 2 at 1.1 cfm, and the Hoffman 75 at .5 cfm.  I have actually used the Heat Timer as a main vent and it worked great for that purpose.



For Radiators, it is just WAY to fast.  In the minimum position, it looks as if it is closed, but it's not.  In minimum at 1 oz pressure, it still vents at .065 cfm.  This compares to a Hoffman 40 at .042 cfm, a Hoffman 1A set at setting 3 (very unreliable because of the sloppy design) .1 cfm, the Gorton 5 at .08 cfm.



So, if I had varivalves in my system, I would close them all the way and see what I had.   If I had a few rooms close to the boiler that overheated, I would install Hoffman 40s.  If there were a few that were still chilly and slow to get steam, then I'd open the varivalve slider about a fourth of the way.   The problem with varivalves in an apartment building is that tenants won't be able to keep there hands off of them.  I am a fan of the good old reliable and slow Hoffman #4 radiator vent. 

years_of_steam

Hoffmans/varivalves

Thanks to everyone! Just to be clear, at the moment I have Hoffman 40's on all the radiators that can take them, except the top floor, and in fact even on one of the top floor front radiators.



I have several radiators that are recessed in the floor and need the tiny physical size of the varivalves because there is no space for the Hoffmans. They are all set to their low position. But they are also in the rear of the building which has never been the problem, as that is where the boiler is. And the top floor rear has no vents on the risers, I have left the varivalves there, set to their low position, and they seem to be venting the risers that feed them, which are not otherwise vented.



It's the top floor front that remains the problem, farthest from the boiler. I am still working on figuring out how fast the steam gets to the top of the risers...where I have 2 Gorton 2's on each riser. That's today's research question. The issue as far as I can make out at the moment is that in order to actually heat the radiators in those locations I need to run the boiler for an extra 5 or even ten minutes in its 60 minute cycle. By that time the rest of the house is way too hot. One of those two radiators is huge, I'll measure it later today. (On the huge one at the moment I have a varivalve at half way, and on the other, slightly smaller one, I have a Hoffman 40.)



In those last 5 or 10 minutes is also when the pressure gets up to the point of fluctuating between 8 and 16-18 oz on the gauge, and I am wondering if I can set it lower and still get the steam up to the top floors.

Dave in QCA

Top of Riser Questions

So, you have 2 Gorton #2 vents on those Risers at the front.  Please tell us about the comparison of how long it takes for steam to get to those vents compared to when the steam starts to go into the top floor radiators that are slow to heat.



When those top floor radiators do begin to heat is there ever any hammering in the pipes? 



What size in the riser?  What size is the main that it comes off of.  How is the slope on that main?  (Especially the part near where the riser comes off.)  Do the rest of the radiators on that riser heat OK?

Dave in QCA

Have you checked the gate valves?

Valves seldom are the problem, but occaisionally they do come apart inside.  I had a new gate valve that loosened up inside, it allowed the stem to rise and it actually threaded completely off of the gate, leaving it in the down position.  Probably not the problem, but wouldn't hurt to double check.  While you're at it, put a level on the piping and make sure that it does not have a backward slope.

years_of_steam

further info from top floor

Thanks everyone!



So with a helper today I was able to track the steam a bit more precisely. The boiler had been off for three hours, just keeping warm for my hot water coil.



Five minutes to start making steam. Then one minute to the end of the long main in the cellar (3 Gorton 2's). There the main branches off to each side, ten feet each way, and then the two risers go vertical. The gorton 2's on the risers are at the top of the vertical runs, just before the gate valves to those last radiators.



After steam reaches the end of the long main, it takes 6 minutes on one riser, 7 minutes on the other riser, to get to those vents on the top floor. Of that, only one minute is in the basement, the rest is the upward time.



The radiator off the 6 minute riser is huge: cast iron, 25 " high, 8 sections, 7 tubes. It is the one that is now slowest to heat. It has a varivalve and changing the setting makes little difference, it only partially heats even after 15 minutes whether it is set fast or slow.



The radiator off the 7 minute riser is a bit smaller.... and a bit farther from the boiler. It is cast iron 25 " high, 7 sections, 5 tubes. It now has a Hoffman 40. It got hot about 15 minutes after the heat reached the gate valve.



The gate valves are brand new, do you still think they are the problem?



During most of this time the pressure on the low pressure gauge on the boiler stayed pretty constant around 2 to 4 ounces, until about 10 minutes after the top floor risers got heat where the Gorton 2's are-- so 10 minutes into trying to heat those radiators. Then it hit .5 on the gauge, rose to 1.1, cut off with the vaporstat.... and continued. (For the last 5-6 minutes I had put the boiler on Manual to over-ride the Heat Timer controls, so I put it back on the timer and waited for the next cycle.)



Maybe you have suggestions about the right air vents for those radiators?



Thanks again.

years_of_steam

answers to Q's about sizes etc.

One front risers start as 2 inches and on the 4th floor becomes 1.5 inches. The other one is 1.5 inches all the way. The radiators on those lines are heating well with their Hoffman 40's. All of them have Hoffman 40s.



The long main is either 2 or 3 inches, the branches are I think 2 inches. But in any event they all get hot in the cellar within a couple of minutes of when the boiler starts making steam.

Dave in QCA

More information needed

If you have recently put new gate valves on the radiators that are missbehaving, that could be a problem.  Undo the untion connections an look inside the valve.  If the passage is wide open than that is not the problem, however, if you think the valve is open but visually see that it is not, than you may have solved the problem.



Otherwise, it appears that the radiators are taking all of the steam that the boiler is making and there is nothing left for the top floor.  So, How many radiators in total do you have.  What is the EDR of each.  What are the ratings of the boiler, Input, Gross Output, and Net Steam, or Steam EDR.   Next, have you clocked the boiler to see if it is actually burning the gas at the correct rate.

years_of_steam

Vaporstat not level, in fact

After reading Bob's recent post I decided to check the level on the Vaporstat and in fact it is out of level, the bubble is positioned just to the left of the center where it's supposed to be. The pigtail is oriented correctly (though before it was changed Friday the old one was oriented the other way, so you look through the hole as you read the gauge).



Is this something to be concerned about or can I just rely on what it seems to be doing (cutting out at 1.1 and back in at .5, when the boiler has run for a long time)... ?

nicholas bonham-carter

Out of level vaporstat

If the vaporstat is a mercury switch type, then it must be level, in order to control the pressure. As the pigtail heats up, it can unwind its loop, and offset the control.

The pigtail loop should always be at right angles to the plane of the internal mechanism.

By now you should have the low pressure gauge installed, and therefore can see whether the vaporstat is doing its job.--NBC