Uneven Main Venting

Jeff_44

I have a one-pipe system that runs quiet as a mouse - no hammer, spitting, etc.

But I'm getting uneven heating results between the two mains. One main is 44 feet in length and feeds four rads with a load of 93 EDR. The second main is 53 feet in length and feeds six rads at a load of 193 EDR. The boiler is rated at 283 EDR and the total rad load is 286 - almost dead on. The first main is vented with a Hoffman 75 (see pic) and the second is vented with two gorton #2's and one Hoffman 75 and yet the first one gets hot sooner than the second. The single Hoffman vent closes sooner (and stays closed) while the other main's three vents only one or two of them stay closed (I can hear one of the gorton's internal rattling when I tap on it).



I overloaded the second main with vents to try to even things out...but I'm beginning to wonder if I have too much venting on this side. And to complicate matters, the vents were piped at the very end of the mains - shouldn't they be back about 18" from the end?



What other issues could make for these uneven conditions?



Any thoughts would be appreciated.

Mike Kusiak_2

Low firing rate?

Sounds like your boiler cannot produce enough steam to completely fill the system. Do you ever see any pressure rise on the gauge. Does the burner cycle by the pressuretrol at the end of a long run?



Even if correctly sized, if the boiler is not firing at it's rated input it will not meet its steam EDR rating. You can check the firing rate of your gas boiler by timing how long it takes for the gas meter to complete one revolution of the 1 Cu. Ft dial. (clocking the gas meter)



With a little math, you can figure out how many Cu. Ft. of gas the burner uses per hour. 100 Cu. Ft produces about 102,000 BTU, so you can then determine if your boiler is burning at its rated BTU input.

BobC

Slope and radiator venting

Jeff,



Check the slope of the slow heating main to be sure it all has the correct slope so you don't have any pooling water, The slope rate of both mains should be about the same.



What kind of vents are you using on the radiators? You may be venting the radiators on that first main too fast. Can you slow the venting down on the radiator near the thermostat so the boiler runs longer?



Also the check the slope of the antler you have the gortons on to be sure you have positive slope back to the boiler.



Do you see any signs (drops of water above the water in the gauge glass) of wet steam?



How long does the boiler fire to satisfy the thermostat and how high does the pressure get before it shuts down?



Bob

Dave in QCA

venting

Venting can be frustrating.  Before I attempt to answer some of your questions, we need to know about your radiator vents.  If your radiator vents are too fast, it can throw everything out of balance, and no amount of main venting will help.



In answer to one of your questions, you cannot put too much main venting on.  You will reach a point where additional vents will not have any effect, but they will not cause any operating problems.  That being said, there is a limit of air flow that can flow through a 1/2" pipe at 1 oz of pressure, and that is about equal to what can flow through 2 gorton #2 vents.   If you add more venting that 2 Gorton #2s to a 1/2" pipe, it will have no effect.

crash2009

Jeff, can you take one more picture

  Need to see how those two mains join together at the boiler.  Everybody here keeps saying "You can never vent too much"  Do you know what size of pipe your mains are?  Yes, in an ideal world, the vents are supposed to be back from the end.  Yours are up and back a bit.  On your main 2, you could put that first Gorton on a T, like you did with the Hoffman, and install an elbow, so your first vent is not on top of the nipple coming out of the main. 



If yours was mine, I would have 1 Gorton and 1 Hoffman on each side.  No matter if the mains are different lengths or diamaters.  This would eliminate your suspicion that you have too much on one side.  Also test the Gortons to make sure they are working and not seized up.  (blow test, right side up, and upside down)  Then let it run for a day, and make note of any changes. 



The second thing I would look at would be the radiator closest to the thermostat, it might be shutting off the boiler before main 2 has a chance to heat up properly.  Shut it off for a day, and make note of any changes.  ie: improvement to main 2



Third, main 1 might be venting through the radiators instead of the mains.  What kind of air vents do you have on main 1's, four rads?  What kind of air vents do you have on main 2's, six rads? 







   

Jeff_44

Thanks

for your input. I think one of the issues is that I have a variety of vents on the rads: varivents, Hoffman 1A, maid-o-mist. There are two BIG rads close to the bolier on the longer main. I have them set slow to allow for steam to get to the end of the line. The rad closet to the t-stat is at the end of the main and sometimes does not get any heat - sometimes is does. I've attached a couple of pics of the boiler piping and the way the mains are piped there.



Also on the long main, there is a take off that goes to a rad in the garage - I removed the rad long ago and the line is capped but there's still steam that travels down this line. In the house it's very hot but in the garage no heat is there - the line is about six feet into the garage. I wonder if I'm losing some heat here?



I'll try some things you've suggested and report back.



Thanks as always!

BobC

Hot pipe

If that capped pipe is hot to the end you may well have a steam leak in that pipe.



Bob

crash2009

I drew a little sketch

 using the Paint program, and saved it as a jpeg.  If you really want to find a solution, you should figure for yourself, how it really looks.  At this point, this is how I see it, and I may or may not have it right.  You told me that you have 4 rads on main 1, and 6 rads on main 2, and recently we have a main 3 going to the garage.  Put all your EDR's and VENT MODELS in the boxes.  The boxes at the end of the mains are for the main vent MODEL. 



Is there a main vent, or leak, in the garage?   

Mike Kusiak_2

Thermostat settings?

Jeff, how long are your typical burn cycles? if the cycle time is too short, the boiler may be shutting down before all the air is expelled from the system. Naturally the longest main will take the longest time to purge, so if it takes 12 minutes to vent the air completely and the burner only fires for 10, it might explain the problem

Jeff_44

Thanks Again

I drew a map detailing the system. One thing I noticed is that on the short main (in blue) there is a T off the main where one rad gets steam on the left side of the T and on the right is the rest of the main. This may not be a problem as this is the side that heats more quickly. On the cycles, the blue main heats faster than the red and the single Hoffman 75 gets hot and closes up. On the red main, the two gorton's and the one Hoff 75 never get hot enough for any of them to close off (you can hear them rattle).



I may have been misleading on the take off that goes to the garage (it's not a main). it's the first take off on the red radiator side and ss it leaves the main, it's very hot - out in the garage the pipe (which is about 6 feet in length) does not get any steam. I don't have any plans to use this line and I wonder if I should cap it inside the house and to let the any steam that is drawn into that line be used elsewhere.



The boiler cycles are typically about 20 minutes in length (or longer in the morning).



The other mystery is that on almost every cycle, at least one radiator does not get heat - it's random so you never know which rad will be cold.



Thanks for the input you've given - you guys are great!

Mike Kusiak_2

Pressure?

Do you ever see the system indicate any rise in pressure?



It still seems to me that you are not generating enough steam to completely fill the system. The fact that you mention that a radiator in different random locations will not heat seems to confirm this.

crash2009

I got your pdf

 turned back into a jpeg

crash2009

Mike is right

Start the troubleshooting at the boiler.  Clock the gas meter to make sure the boiler is putting out what it should be.   http://www.mstove.com/imgs/gas.pdf  What is the model of the boiler?

Jeff_44

I'm on it...

The boiler is a Dunkirk PVSB-4D installed in Jan of 2006. In looking at the 0 - 30 gage, it's clear it's stuck on '1'. I'll stop by my local supply house and get a better gage. A while ago, the boiler came on the three rads got no heat while the other seven were nice and hot. I just had the boiler cleaned at the beginning of the heat season - the mechanic took out the three burning tubes to clean - is this where the proper firing rate is determined. I'll let a pro handle this.



On this Dunkirk boiler, the gage is recessed in top of the boiler. Should I my new one on a pigtail?



Thanks again.

Jeff_44

I Clocked the Meter

And the '2 feet' dial went around one time in 68 seconds. I divided this by 7,344,000 and got 108,000 and the boiler is rated at 112,500 BTU. I don't run these numbers in my everyday life but it seems that 108 is lower than 112.5. If I did this right than the boiler is under firing by 4,000 BTUs. I don't have enough experience to know if the difference is significant or close enough for jazz.



As far as the pressuretrol, I don't think it's cycling at all. But on my old 200,000 BTU 1940 Weil McClain, I don't remember the pressuretrol shutting cycling either.



I did notice that on a recent cycle, I could hear the hoffman 75 opening and closing while the boiler was on. Don't know what that means...



Thanks so much for your input.

BobC

Not a lot left on that table.

Your running at about 96.4% of the rated firing rate, when they come to service the boiler ask them to see if they can crank up the gas pressure a bit; just don't expect a significant change.



Rather than replace the original gauge just add another one on the pigtail. Go to  http://www.gaugestore.com/prodinfo.asp?number=33020 to see the generic low pressure gauge a lot of us use. Pipe it like the picture but add a 1/4" union between the pigtail and the T if you can, it will make dis-assembly for cleaning a lot easier.



Bob

crash2009

Here is the manual

http://www.ecrinternational.com/secure/upload/document/397.pdf

Dave in QCA

Very slightly undersized boiler...

It appears that your boiler may be very slightly undersized for the actual load of your system, or possibly, your radiator venting is to aggressive and is throwing your system out of balance.  I am cutting and pasting into this discussion, the words of BoilerPro, Dave Bunnell. 

You may well see this as a potential solution for systems that are not heating evenly due to “undersized” steam boilers….cut down the venting rate of the radiators and vent the mains well.   Well you’re right and in doing so we will be following the advice of one the ancient guru’s  of steam  “Vent your mains quickly and your radiators SLOWLY, but completely”. 

I dont' know which maid-o-mist vent you have, hopefully it is a 4.  My recommendations are, set your Hoffman 1A vents to 2.  Set your Dole vents to 1.  Let the boiler run and see where you are.  You can make adjustements as necessary to balance the system, but slow venting on the radiators is probably going to be necessary to get your system balanced.

crash2009

So the boiler is putting out close to what it should,

 I think Bob said 96%.  You said the boiler runs for 20 minutes then shuts off.  Maybe 20 minutes is not enough to fill both mains.  There are 3 ways that I know of, for the boiler to shut itself off.



1 The thermostat is satisfyed.

2 The Pressuretrol shuts you down because you have built too much pressure.

3 The boiler has run out of water, and the low water cutoff has shut you down. 



1-Would both sides get hot if you jacked the thermostat 5 or 10 degrees higher than normal?  The thermostat may need an adjustment (cycles per hour, differential, or anticipator)  If you dont have the manual, what is the model, I will get it for you.

2-You can't really test this one until you get a couple gauges installed.  You will need a 0-3 psi gaugestore.com and you said the 0-30 doesn't work.  Code says you have to have a 0-30.  So you need both.

3-Observe the sight glass, during a cycle.  One Cycle could take awhile as you have to measure from the minute it turns on, including when it turns off, and then when it turns on again.  Today mine is 15on, 35 off, a 50 minute cycle.  Make your self comfortable, this might take an hour or two.  You will need a clock, tape measure, a pen, paper and 2 beers.  Start with the time you got there and started watching.  Measure how much water is in the sight glass. Note if the boiler is running or off.  When you hear the hoffmans clink record the time, water level, go over and feel the Gortons, (they should get hot a bit before the Hoffmans clink) Just hang out down there for one complete cycle and write down your observations and sounds, but most important the height of the water at each event. 



These observations above will help us help you figure out whats going on with your system, and help you determine whats normal and whats not. 

toniboiler2

right btu for hot water

i am looking for a hot water boiler to give me 60 gal of hot water per min.someone suggested 1mil 200 btu that only gives me like 47 gal. a min. dose any one have the ansew for me please i need 60 gal of hot water a min.

Jeff_44

You guys are amazing

and I appreciate you're sticking with me on this. I bought a new gage today at our town's local supply house. The best they had was a 0 -15. I put it on and ran the boiler - I set the t-stat for a couple degrees higher and let it the cycle begin. I didn't see the needle even move - not once and the pressuretrol didn't shut kick in either. It's set for .5 (the lowest it can go). I did clean the pigtail a couple of days ago and it was full of junk.



On this particular cycle, the boiler ran for about 50 minutes and every rad was nice and hot.



Also, I noticed that as the steam filled the mains, that the drip connection to the wet return (which is directly below the main vent) was getting just as hot as the pipe attached to the main vents. Should steam be going down into the wet return as the boiler heats up?



I wonder if I should shut off all the rads and let the boiler run to see if any pressure builds up. I'm wondering if I could have a steam leak somewhere in the system. Yesterday, after the boiler finished its cycle the auto water valve came on and put a small about of fresh water into the boiler.



Thanks again for your guidance, advice, and help!

crash2009

It must be hard for you to see the sight glass

  After looking at the manual, yours appears to be under the smoke pipe and the boiler riser.  You said you pulled a lot of gunk out of the pigtail.  That pigtail is connected to the upper part of your sight glass.  Is it possible that the sight glass tapping is plugged also?  This would explain why the pressuretrol is not working.  If so, this is not good, and possibly unsafe.

Is the gauge on this same pigtail as well?

crash2009

See page 28 of the manual, and look at part #11.

  If the pigtail was plugged, likely so is part #11.  I suspect that your boiler is shutting down on low water and that is why it doesnt run long enough to heat the entire house.   



Also read page 17 of the manual, it explains what the safety controls are for, and why they need to be working.



And I got some bad news for you.  If it is shutting down on low water, You might have to re-pipe it to manufacturers specifications to correct the problem.  Manufacturers piping specs are on page 6.

Jeff_44

It's not shutting down on Hot water

In fact, the cycles are quite long - at least 20 minutes. I removed the pigtail as well as the valve at the top of the site glass and it (part 11) from page 28 was wide open and clear. I thought there would be lots of gunk but alas, there was none. When I put the new gage on, I installed it in the old one's place. But as I said, it didn't move at all. (I do remember that the old one used to show a pressure reading.) When I had the pressuretrol of the pigtail, I checked it and it was clear. Then, just to trouble shoot, I put the new gage atop of the pigtail (in place of the pressuretrol and ran the boiler - again, the gage did not move at all. So I shut it down and replaced the pressuretrol. As far as I can tell, it's shutting down when the t-stat is satisfied.



The T-stat is a White Rogers - type no. 1F80-361 - I don't think it is specific for steam because it has a fan switch on it.



I think my next move is to close down all the rads and the main on each side and cycle the boiler and see what happens.



This is getting frustrating - it has been working so well and without trouble since we had the boiler replaced in 2006.



I have to say, I think what may set it off is when my daughter wanted to sleep in the attic during vacation and asked me to turn the radiator on up there. I had it completely disabled but hooked up back to the system and let is run up there for a couple of days - I've since disconnected it.



Thanks again for your help.

Mike Kusiak_2

Hole above the water line

Jeff, do you notice any unusual amount of steam or smoke from the chimney when the boiler is running? If you had a hole in the boiler above the water line, steam could be escaping up the chimney, which would explain why you now develop no pressure. It would also explain why the water autofeeder is coming on as you mentioned.

Jeff_44

No -

I don't really see any exhaust from the chimney when the boiler is firing - the only time I can see anything is when the outside temp is very low - I'm in upstate NY and it's in the teens tonight so I'll check the chimney in the morning. The boiler is new enough it should still be under warranty (I hope).

Jeff_44

No -

I don't really see any exhaust from the chimney when the boiler is firing - the only time I can see anything is when the outside temp is very low - I'm in upstate NY and it's in the teens tonight so I'll check the chimney in the morning. The boiler is new enough it should still be under warranty (I hope).

crash2009

Here is the manual for the thermostat.

  In the configuration menu (page 4) there are 2 settings for cycles.  One setting is FA and the other is SL.  FA cycles at the system at less than 1 F.  SL cycles at 1.5 F.  Steam should be set for SL.  They suggest that other settings can be achieved, but they recommend that you call a technician.

Jeff_44

Thanks Crash2009

And everyone else for your help. I checked the thermostat and it was set to SL. This morning, when the boiler came on, it cycled for 1 hr and 15 minutes. It was 14 degrees outside and we keep the house at 60 at night and up to 64 during the day. All the rads got nice and hot on this long burn.



I watched the chimney this morning right after I bumped up the temp on the thermostat - the boiler had been off for an hour or so but on the initial start up I could see some white exhaust - but this came right away before the boiler was even making steam and it came after I shut off the boiler (and we have a automatic flu damper that open and closes with each cycle) And as is usual, we typically see some white exhaust when the temps in the teens. On warmer days (in the 20s or 30s) we don't really see any exhaust from the chimney. I guess I'll have to wait till it's a little warmer to see what's coming out of the chimney. Is there any other way to tell if there is a steam leak above the waterline.



We've maintained our boiler with yearly cleanings, etc since it was installed in 2006. Dunkirk warranties the heat exchanger and cast iron sections for 12 years so I hope if there is a compromise in the system that we're covered.

Mike Kusiak_2

Pressure?

Did you see any measureable pressure on the gauge during the long burn this morning?

crash2009

Well Jeff, we eliminated a lot of possibilities

  I just searched the entire thread for "glass" so I could see how many times it was written.  We have 4 references to the sight glass, but no answer to sight glass questions.  Maybe your solution has something to do with the answers to our sight glass questions.  I have repeated the references to sight glass for you to review. 

Observe the sight glass,

It must be hard for you to see the sight glass,  

removed the pigtail as well as the valve at the top of the site glass and it (part 11),

 Do you see any signs (drops of water above the water in the gauge glass) of wet steam?

Jeff_44

Sorry I missed this...

I can see the sight glass well enough and no, there is no evidence of water in the top of the glass. When I removed the sight glass to check if the fittings were plugged (as was the pigtail), they were bone dry.



Just now I tried an experiment. I closed all the rad vents in the house. Fired up the boiler until both sets of main vents shut. I was glad to see that they both shut at almost the same time. I quickly shut off the boiler and then let the system set for about five minutes. During this time, neither set of main vents open up. I then opened one radiator (the biggest one) and it hissed like crazy - releasing the pressure.



I then opened the four rads on the first floor and fired up the boiler again. Just as before, the shorter main vents closed up before the longer ones - the longer main vents never shut all the way. I checked the four rads on the first floor and the biggest one near the boiler had the most steam. It seems that this one may be a steam hog and taking steam before the mains can be fully cleared of air.



As I understand it, the mains are supposed to be cleared of air first. Once the main vents close, this allows the steam to work its way into each radiator per individual venting speed. This occurs because the air has been replaced by the steam all the way to the end of the mains and the steam has no where else to go except to the open air vents in each individual radiator.



I'm a little worried because when I tried my experiment, the gage did not register, nor did the pressuretrol shut down the boiler. I mounted the gage in place of the old one and I think the fitting is plugged so I'm going to mount it on an 'antler' on the pigtail along with the pressuretrol.



Is there a safe way to test the pressuretrol?



Thanks so much for all your help!

crash2009

We may be on to something

1- When you removed the pigtail, wasn't there any water in it?  There should have been.

2-Good experiment, this shows the main vents are working and holding pressure.

3-Slow the venting on that rad. 

4-Right On!

5-a-On mine, I had to clean the tapping all the way inside the boiler, there was a piece of teflon blocking the hole.  It was laying there like a flapper, I could blow in but could not suck out.  This prevented my pressuretrol and gauge from working.

5-b-Does your sight glass ever have water in it?  One or both of the tappings may be plugged (more likely the top one), right inside the boiler.

5-c-If the upper sight glass tapping is plugged pigtail/antler/gauge/pressuretrol does not work.  

6-There is a test rig that you can build, I will look it up for you. 

crash2009

Pressuretrol Testing and Adjustment

http://www.heatinghelp.com/forum-thread/133195/How-does-pressuretol-work

http://www.heatinghelp.com/forum-thread/132867/How-do-you-test-Pressuretrol

http://www.heatinghelp.com/forum-thread/128249/why-do-Honeywell-vaporstats-suck-so-badly

Jeff_44

There is water in the sight glass

Yes, there's water in the glass. When the boiler is off, the water is about 2/3 full. When the boiler is running, the glass is about 1/3 full - but there is no water forming at the top of the sight glass. When I removed the pigtail, a little water trickled out - should it be full of water?



Over the last few days, I've put a piece of masking tape to mark the top of the water level in the sight glass - when I check it after the boiler cycles, the water level returns right back to where it was before.



Thanks for the info regarding testing the pressuretrol, I'll do that next.

crash2009

Bump

Bump

nicholas bonham-carter

60 gal hot water

did you ever repost this on the "wall", or if you have a steam boiler, then repost here.--nbc

Steve_175

Required Reading

Fig 6B on page 7 should be a required sticker on the side of every steam boiler made.