gurgling in one room, no heat in another

puff_puff_hiss

---reposted from main wal---

Good morning,

I have read Dan's book and searched this site and I've had trouble finding anyone with my specific set of circumstances. I am hoping that someone can help me!

I am new to the house, first winter coming up. Boiler itself is just a few years old and works seemingly perfectly. All the radiators in the house are a different story. Upon first firing up the heater for the first few cycles, I had pretty severe water hammer. That lead me straight to the books and research. I have taken care of most or all of the hammer (from time to time it seems to want to remind me that it can hammer if it wants to) by trouble shooting pitches and vents. All that said, I think i have cause other problems that I didnt notice when it used to hammer..... or maybe i just couldnt hear these new problems over the hammer.

I have the one pipe system with two, arguably three mains. each main 1 and 2 has a freshly replaced vent, main 1 size gorton 1 and main 2 is maid o mist 4 (these were replaced on a like for like basis for what was already there,  i will trouble shoot this at a later time since the maid o mist 4 is probably too small).      generally speaking, i think i can get the two mains and all radiators on those runs figured out by continuing to troubleshoot pitch and vent size and having a little patience. I have already taken it a pretty far way from where it was. My house is organized as follows:



Main 1 feeds 1st flr living room (biggest radiator in house), 2nd flr master bedroom, 2nd flr master bathroom, and 1st flr office.



Main 2 feeds 2nd flr hall bathroom, 1st floor family room (where thermostat exists), 2nd floor guest bedroom, and 1st floor powder room.



Main 3, even though it is not a horizontal run in the basement with a main vent, but rather a third pipe coming from where mains split from each other. This third pipe goes basically straight up from where the mains split off (with 45's and 90's to get to a exterior wall so that it can rise to the 2nd floor). This third "main" rises from basement in an exterior wall to the ceiling of the 1st flr, and takes a horizontal 8 foot horizontal run where it turns up to feed the nursery on the 2nd floor.



Most of my problems seem to be on the line that feeds the nursery. From the minute the boiler turns on, the nursery radiator starts puffing air, arguably the fastest one in the house to start with air. However, every radiator in the house will come up to full warm in about 20 mins and the one in the nursery keeps puffing along, not even the supply valve gets warm at the 20 min mark. It continues to puff past the 30 and even 40 minute mark, most of the other boilers vents have closed and they are warm and silent by now. maybe 40+ mins into the cycle, the radiator switches from blowing air and blows 6-8 ounces of water out of the vent and then things start to heat up.

regarding pitch of this line, If anything, i tend to think the radiator and horizontal supply pipe might be over pitched. to troubleshoot water hammering on that line, I raised the enitre radiator about 1 inch on the supply side and 1.25 inches on the vent side. I raised the entire radiator thinking that the 8 foot horizontal leg might have had water laying in it and since there was some play in the pipe that went through the floor, I knew i could get some pitch back. Up til the time I made that adjustment, the supply pipe as well as the pipe in the basement that feeds this radiator water hammered violently and that has subsided since raising the whole thing. However, i never had the 8oz of water thing happen.... before raising the radiator, i would get some spitting, but nothing too too bad.

I guess my questions are:

1) how can i displace air out of that line for 30-40 mins straight without the line and radiator warming up?

2) Can overpitching cause that?

3) is the vent too big? is the vent too small?

4) do i need to slow the rest of the house (main 1 and main 2) down in order to force more steam up that third leg to the nursery? bear in mind that i had water hammer in main 3 before replacing main 1 and main 2 vents and repitching the radiator in the nursery.

5) why, if i am over pitched, am a getting so much water (8oz) up to that vent? especially without hammering. I would think the steam would need to build pressure in the line and throw that slug of water up the line, but i don't think anything like that is happening.

6) will my heating system behave so much differently when it is winter time and 20-40 degree instead of 40-65 degrees like it is now that i should just be more patient and wait and see if the system runs better when it cycles more frequently throughout the day?

7) I have a size D on the nursery radiator, it blows air but doesnt get hot. anything aside from slowing down the rest of the house that anyone can think of to help get this balanced?

8) do i want to mess with slowing main 1 and main 2 down?

My system is operating on the low side as another adjustment I have made to the pressuretrol. It was running up to 3PSI at points during the cycle, and now it is running less than 2 always during the cycle.

The guy who lived there before me only had two or three radiators in the whole house on (had supply valves off) and I suspect he threw the system all out of balance by changing vent sizes to meet his needs in the way he heated the rooms he wanted to heat. He only used 1 of the three bedrooms for example and I believe he kept the other two off. (this is somewhat speculation, he may have shut valves off to pass home inspection without getting a water hammer comment on the inspection report).

As an aside, It sounds to me like my main 1 and main 3 may have a wet steam compared to dry steam. this is just a gut feel judging on what i can hear even on the radiators that work well. I hear some very quiet gurgling and water dripping/draining at the different radiators. on main 2, i don't hear any of that and everything gets warm and is quiet.

So sorry, lots of questions. I am wiling at this point to bring in a professional, but the one conversation i've had so far in taking steps toward hiring someone, lead me to the guy telling me that he'd only be doing all the things I am doing and charging me to do it... not sure if that is what i need.

your help is greatly appreciated

nicholas bonham-carter

see my reply to this on the wall!

couldn't cut and paste so it's on the wall.--nbc

puff_puff_hiss

follow up info

i called my main vents out as D's in my original post, but i could be mistaken as I am not at home to double check. I replaced "like for like" with what was there and didnt really pay too much attention to the number before installing, my mistake there clearly - but they do seem to allow air to pass as soon as boiler starts and then close shortly thereafter.   - i will double check that and reply tonight.



with that being said though, even with the mains venting correctly (which i think they do because they start puffing immediately too, something is going on with that riser/horizontal leg/radiator that goes nearly directly from boiler to nursery (bdrm). taking 40 mins to get a blast of water followed by finally heating up.



any additional help would be appreciated.

Paul48

Piping

Can you post some pictures of the near-boiler piping? Your description of the mains sends up some "red flags", but a picture is worth a thousand words.

Rod

Need Pictures

Hi- As Paul mentioned pictures really help. Also could you tell us the make and model of your main vents and of your radiator vents?  On the boiler pictures take them from different sides and from back away from the boiler so the boiler and the piping show in the same picture. This allows us to trace out your piping so we can see where it leads. If we need detail we can zoom in.

- Rod

puff_puff_hiss

vent type

ok,  thanks to everyone who tuned into this thread!!!!  

on main 1, which services the front of my house and has 1 problematic radiator on it (the master bedroom that is gurgling and sounds like it is full of water, albeit working),  the main vent is a Gorton #1. 

on main 2,  which services the back of my house and I would consider to be working nicely, meaning most radiators come up to speed at similar times and are quiet, I have a Maid o Mist #4.    It is possible that Main 2,  despite having what i believe is an undersized main vent,  is working well because the last radiator on that line that is on a riser just before the main vent has a radiator that has a Gorton #1.  That radiator gets hot very quickly.   I think it must be helping what i believe is an undersized main vent to help air get out of the way on that line. 

Main 3,  which as i mentioned isnt really a "main" but rather piping that comes off the boiler piping (main 1 specifically) and heads to the nearest exterior wall and rises 10 feet to the first floor ceiling where it takes a 90 and heads about 8 feet on the horizontal before taking another 90 and feeding through the second floor into the nursery bedroom radiator which currently has a D size vent on it.  That is the only vent for that "main" as far as i can tell, unless there is a vent buried in the floor or the ceiling somewhere.  This is the radiator that starts venting air right when the boiler kicks on and doesnt stop puffing until 40 mins later when it blows about 6oz of water and then heats up quickly.   There is plenty, possibly too much pitch on that line as far as I can tell.    This radiator is the reason that I am spending hours trying to learn about this system -  it is the baby's room and its just not working for me to have it huffing, spitting, banging, and spilling. 

here is my plan of attack for this weekend: 

1) I don't want to mess with main 2 because it is the only one that works well in the house, but i understand it isnt vented the way conventional wisdom would say to do it. I will therefore change out the maid o mist 4 on the end of the main with the gorton 1 that is on the last riser of that same main which currently feeds a 1st floor powder room.  

2)  The water level in the sight glass looks about right, about halfway full... but i don't know if that means the wet return is or isnt full or what that means.  I read another thread ("knocking pipes" by Vicki S)  and I feel like her and my problems might be similar.   I had an incident that i forgot about: after I settled on the property but before i moved,  a contractor put the thermostat to 85 and left the house.  The boiler ran for close to 24 hours  (it was end of last winter) and filled the house with steam through a supply valve that was leaking on a radiator that wasnt hooked up.   This is pretty similar to what Vicki S did.   I hear gurgling in the master bedroom on main 2, like there is a lot of water in the radiator,  and I get lots of water shoot out the vent on main 3,  and i feel like I am having wet steam or too much water in the system.  I think Vicki S experienced the same thing after a similar episode.  I want to see if my wet return is too full but not sure how to do it.  I have a drain valve on the wet return with a hose hooked up to it, so i guess someone has done it before.  

I will post pictures of near boiler piping in a few mins.   

puff_puff_hiss

pictures

picture 1 shows the wet return along the wall and turns down in the background of the pic and in the foreground of the picture is a hosebib that is labeled "boiler drain" with the tag that hangs from it.   in the background, you can see the piece of black hose on the wet return drain valve. 

picture 2 is the front view of the where the wet return turns down toward the floor and the black hose on the valve for the wet return drain

picture 3 is the site glass, the pressuretrol, gauge, and other. 

picture 4  is meant to show the near boiler piping..  What you are looking at is as follows: 

Main 2 is the first insulated pipe you see branching off the 4 inch line that comes off the top of the boiler.  it is heading slightly toward me but mostly to the left toward the read of the house. 

Main 1 is the one that is heading straight toward me and over my head.  that services the front of the house. 

Main 3 is the insulated pipe that you see turn horizontal to the left at the very base of Main 1.  what you cant see in the picture is that main 3 comes off Main 1, goes bout 10 incches on the horizontal as shown, turns 90 degrees and heads away from the camera toward that wall in the back near the window, turns 90 again and goes in front of that window in a bay of the floor joists, turns 90 degrees again and heads up to that nursery bedroom radiator in the exterior wall (taking an 8 foot horizontal run in the 2nd floor floor joists along the way) 



yes,  that is an old set of tv rabbit ears on top of my boiler, and no, I don't have the antennas hooked up to the boiler for better reception.   





Main 1 is the insulated  

BobC

Check pitch

Use a level and check all the mains and runouts that you can get to, don't rely on your eye. make sure you don't have any dips where water can collect. You mentioned the problem radiator has about a 8 foot run above the first floor ceiling. Check to see if the floor above is roughly level, buildings settle with the passage of time and you might have to jack that radiator more than you think.



That one radiators valve might have a problem as well but rule out the piping before messing with that. Also does the water level in the gauge glass move around a lot when making steam?



Bob

puff_puff_hiss

thanks for feedback

thanks so much for the reply. 

on main 3 with the horizontal run,  I definitely have pitch and a lot of it, not just by eye.   i have jacked the radiator (both supply side and other side) to make sure the horizontal run has lots of pitch.  This removed the water hammer that used to happen at this radiator and to this line in general (since some of the water hammer was on that line in the basement near the boiler), but it has not stopped the water from coming out the radiator vent.  if anything, it has made the amount of water coming out the vent worse.  Its also conceivable that something else i did besides changing pitch removed the water hammer because at the same time i changed the pitch, i replaced "like for like" the main vents on 1 and 2 and the radiator vent on main 3.  (which is the only vent on main 3) 

 

The water in the site glass does move around when making steam.  it isnt crazy movement, but it is movement.  I don't know enough to know what is normal.  can you help define normal movement for me?



one final point,  the supply valve at the radiator on main 3 (so the valve right at the radiator in the nursery) works to shut steam off to that radiator.  it does not sound like it leaks steam, and when you open it, you immediately get air venting out the vent side.  I am not certain, but at least it seems to be functional.   the one thing i have noticed about the supply valve though is it takes a pretty good amount of turns to shut it off completely or open it completely.  I'd say 15 or 20 full turns of the wrist from close to open, maybe more?



 

Rod

System Problems.

Hi- Does each main have a return pipe attached to the far end (away from the boiler)?

What is the maximum pressure at which your system is now running?

= Rod

puff_puff_hiss

answers

just main 1 and main 2 have returns that drop down at the end of the main near the main vent. 

the max pressure my boiler was running at when i first started it this year,  the first few days when i still had lots of hammering, was 4 psi.  I opened up the pressuretrol and turned back that dial and now it looks like i am always at or below 1.5psi.

   

please bear in mind that main 3 is not really a main... because it doesnt have a main vent per se.   I just call it out as main 3 because insulated pipe runs off my boiler in 3 different directions,  main 1 to the front of the house, main 2 to the back of the house, and main 3, which is essentially a riser off main 1, but it utilizes thicker piping piping than my other risers that come off the mains.

 

      

BobC

#3 main pitch different than 1 and 2?

You said main #3 has plenty of pitch, does it all pitch back towards the boiler so all the water can get back to the boiler? If it were pitched the other way water would be trapped.



It's hard to be sure but in your picture it looks like the other two mains start high and pitch down away from the boiler and I assume that the wet returns are at the end of each of those two mains?



Also you might be better off using much slower vents on the radiators to slow the delivery of steam which would also slow the rate of condensation. Gorton D is a very aggressive vent and a Gorton #1 on a radiator is also just as fast as the D. How long is each main and what size pipe are they (outside pipe circumference)?



Bob

Paul48

What

you are calling main 3 is dumping its codensate back in the header, which will create very wet steam. That needs to be fixed. I know it's a bad position,but I'd like to see a better picture of how all 3 "mains" tie into the header.

BobC

That would be made even worse by the fast venting

Then if we break that third "main" before it gets back to the header a drip could be plumbed down to the return for the two mains (below the water line). Before doing that I'd still like to see how that line works with a much smaller radiator vent on the nursery radiator.



Bob

Paul48

Raining

Main 3 is raining condensate into the path of the steam for main 1. It appears to be teed in where main 1 comes off the header at 45*?

puff_puff_hiss

This is great!

Thanks again everyone participating.



Couple answers:



1. Main 1 and main 2 are pitched away from boiler with wet returns at the far end of each. You can see where it runs along the wall in Picture 1 and where it drops to nearly floor level in the back of picture 2.



2. Main 3 is pitched entirely back toward the boiler from the far side of the radiator where the vent is all the way back to the boiler. It isnt a true main as it isnt vented and doesnt have a wet return. To the comment that it is dumping water back into the boiler through the header, that is probably very accurate. Where it is tied into the intersections of main 1 and 2 at the header, it is pitched back to the radiator.



3. Main 1 and 2 have 8 inch outside circ. And are both about 28 to 30 ft. Main 3 and all other risers have a 6 inch outside circ. The header has an outside circ. Of 12 in.



4. Interesting comments...i agree that condensate from 3 is going into the header and even back to the boiler. I can drop a condensate drain in the horizontal run on 3 that crosses in front of the window and tie it into the wet return. That would prevent returning condensate from getting to the header.





I can slow everything down from a venting perspective (except main 1 and 2 of course) this weekend and see what happens. Do i only buy gortons if buying new or will maid o mist work as well? If i need to drop a condensate line off the horizontal part of main 3 that crosses in front of the window, that will take me a week or so to gather the materials and get my helper lined up.

BobC

Time for an experiment?

I can't tell from the picture but your probably right about it coming off the 45 that comes off the main and it sure would make for wet steam. 



I suspect that there is sitting water someplace in the ceiling run to the nursery, not enough to block the pipe for a long time. That pipe might take a jog up inside the ceiling and that could be where the water is collecting. The steam condenses as it flows over that sitting water making more sitting water. I think the puffing stops  just as that slug of water is getting shoved into the radiator and out of that cold vent and then steam enters the radiator. Maybe the vent is damaged and can't seal against water the way it should.



If it takes a lot more turns to open and close that radiators valve there might be something going there. I don't have a clue how to verify any of this without being able to see the pipe above that ceiling and that gets messy.



Maybe it would be worthwhile to install a slow vent and see how that works and then unblock that radiator to eliminate the possibility it is pitched to much (make sure the radiator itself has correct pitch).



I just saw your post and think you should consider venting all the radiators relatively slow and the mains fast. You could use a Gorton #2 on each main or at least 2ea Gorton #1's on each main to make sure you get all the air out fast. Then try small Gorton's or Maid-O-Mists on the radiators; if you can get the MOM's that come with multiple orifaces it makes it easy to experiment or you might be able to buy the small ones and drill them out if you need a larger orifice (I'm not completely sure about that).



Bob

puff_puff_hiss

Not the pitch in the horizontal ceiling run i dont think

I think i can rule out water laying in the horizontal run in the first floor ceiling that feeds the nursery radiator. I disconnected the radiator, tried to dump it out, it was empty. Then i raised the radiator 3 more inches for a total of 4 inches raised and reconnected. There was that much play in the supply pipe that came through the floor. I Cycled the boiler with the same watery result. Its only an 8 foot horizontal run so taking that radiator up 4 inches has to be giving it pitch and lotss of it

Paul48

puff

You're gonna have to get a steam pro in there. Where did they tie the wet returns together? Is that point above the normal water line of the boiler. Pitching the wet return is silly,it's always full of water.I hope that gradual pitch does not increase to the end of the mains.

puff_puff_hiss

Wet return pitch

--- deleted---- dont want to derail thread.

BobC

i saw that post

Just verify that the two returns are tying together below the water level of the boiler. If they tie together above or just at the water level things get strange.



Bob

puff_puff_hiss

Wet return height

The wet return starts at end of main 2 and follows outside basement wall around, picks up the wet return from main 1 at a height of 18.5 inches off the ground and continues around basement wall back to boiler. The water in the sight glass is 27.5 inches off the ground. I dont think my basement floor is 9 inches out of level. So i think its safe to say wet return joins each other below the waterline

BobC

OK

I just wanted to make sure because you just don't know unless you ask.



i assume you read my edit of the post above about themain and radiator vents?

Bob

puff_puff_hiss

Yes

Main 3 condensate is definitely going back into the boiler through the header. The reason for that would be that it branches off main 1 well below the high point of main 1 where any condensate on the near side (from the point of view you see in the photo) of the high point flows to the wet return. Not sure what happens when condensate goes back to the boiler or if the condensate would turn back to steam as it arrives back to the header.

puff_puff_hiss

Bob

Yes, i am reading and preparing to experiment following your advice this weekend. I have some more pics to post tomorrow too. I am very appreciative of all the help. I do have confidence i am going to figure this out with some help. Between my dad and i , we have the capabilty, tools, and know how to make just about any change.... We just dont have the expertise to know what changes to make other than following the process of elimination.

Paul48

puff

Read the section about "A" dimension. The vertical drop is critical. http://www.comfort-calc.net/Steam_FAQ.html

puff_puff_hiss

Dimension A

I can estimate my dimension A on main 1 and main 2 to be about 35 or more inches. The dimension A on main 1 looks to be more than same dimension for main 2 because main 2 pitches away from boiler slightly more plus the retrun pitches slightly down between main 2 and main 1. Both are more than 28 inches of drop though. I can post a pic of the wet return tomorrow as well. 

puff_puff_hiss

more pics

i took a picture of the near boiler piping and added arrows to show which way things were pitched.   main 2 to the left pitches away from boiler after it gets to its high point at top of picture,  main 1 to the right does the same.   What i've referred to as main three is in the middle, tying into main 1 near the header, pitches back to the boiler.  Main 3 services only the nursery radiator and has no wet return or main vent.   any condensate from that line comes back down from upstairs and drains back into the header and back into the boiler through the top. 



the other picture is of the smaller of the two dimension A drops.  it is the wet return on main 2.  I cant get all the way back to get an exact number on it,  but I estimate it to be 30+ inches vertical and then turns and goes another 16 or 18 inches  on the angle to get to the bottom of main 2.  The larger diameter pip you see at the top of the picture is my sewer line.



***dumb question,  but is my header pitched the wrong way?     in the previous pictures i posted,  there is a vertical pipe that drops from the right side of the header down to the side of the boiler.  without knowing for sure, it would make sense to me that condensate in the header would be better off flowing left to right and dropping down that vertical pipe into the wet return piping rather than flowing back in the top of the boiler.   I can't imagine the installer would make a mistake of that magnitude, but i guess it could happen?  I put a level on the outside of the insulation and I am sure that my arrow is right,  i guess if its wrong, i need to tear the insulation off to double check. 

BobC

That feeder looks ok

It might not be optimal but it should be ok if we get the rate of condensate down to a reasonable level. That picture tells me the condensate is not raining water on the main or header so you should not have to install a drip on the nursery feeder. You should still change the venting rates on the radiators to slow down the production of condensate.



http://www.maid-o-mist.com/jacobus.html



This shows you the orifice sizes of the various maid O Mist air vents, If memory serves you can buy the smallest vent, unscrew the orifice and drill it out to your needs. i would start with everything small and adjust from there.



Having the header pitched like you said is not good but lets wait on that till we address the venting, it may well work out ok in spite of itself. Steam systems can be pretty forgiving.



Bob

Rod

Checking Pipe Slope

To check the pipe slope don't remove the insulation! Just use 2 awls or long finishing nails. If you have a choice, get the awls with a flat spot as it is easier to balance the level on.  Poke the awls through the insulation where there isn't a fitting till they touch the pipe and put your level on the flat spots.

- Rod

puff_puff_hiss

Awls!

What a tip! I will get the vents slowed down tomorrow and report back. Hurricane prepping got me side tracked today.

puff_puff_hiss

funky looking sight glass

Hi,

I tried slowing down a few radiators by reducing the vari vent.  But through all my research here on this website,  i started to think it was something else, particularly a thread made by Vicki S about accidentally running the boiler very hard for a long period of time and thinking that it was now overfilled with water (which running the boiler hard by accident and venting steam into the house in mass quantity while no one was home is something that was done to my home just prior to me moving in - a long story that involved a contractor turning on my heater and the vent being removed on a radiator and the thermostat not getting satisfied so it just ran and ran and ran and blew steam into the house through the non-existent vent).

So anyway,  last night,  the radiators all clanked,  spat, and sputtered along in the middle of the night, and this morning when i got out of bed, they were all cool to the touch since the boiler hadn't cycled in two hours.  So before the boiler started on its next cycle, i decided i would run downstairs and try to drain a little water out of the boiler.  I took about 1.5 to 2 gallons of murky water out of a combination of the condensate drain hose and the boiler valve itself.   The water in the site glass dropped from where it is in this picture to about 1/4 or a 1/2 inch from the bottom.   The automatic water fill did not kick on, even though i know from previous testing that it works.

The boiler fired up a few minutes later and the entire house came quietly up to warm,  all radiators, no hissing, sputtering,  water out of vents or anything. 

You can see in my previous thread that i had a host of issues including spitting 6-8 oz of water out of the radiator in the nursery before it would warm up as well as some water hammer and other problems. 

can anyone make sense of this?  was it a coincedence that everything got warm this morning quietly?  or can too much water cause all those problems?  how can too much water happen?  how can I make sure it doesnt happen again if this is what you think caused all my headaches?  

Final question.  the water in my sight glass looks like it has some weird dust or gas suspended just above it.  the suspended dust/gas/whatever it is bounces with the water as the water bounces about 1/2 - 3/4 inch up and down as the boiler cycles.  Is any of this any more of a clue to what is happenning in my system?

Do i need to skim the boiler to remove whatever this is? 

puff_puff_hiss

one more picture

here is a slightly better view of whatever funkiness is in my site glass -- just below the little reflection of the flash on the sight glass is where it switches from water to whatever else is in there.   it almost appears to be suspended, whatever it is,  but i cant be sure.

Mike_p

response

Hi,



I had similar issues with my steam heat system when I moved into my house last year.



To address the water hammer, I needed to make sure all the radiators were pitched at an angle to allow the water inside the radiator to drain back into the supply piping. If the radiators are not pitched back to the supply piping (and shutoff valve), the water sloshes around inside when new steam enters the radiator and causes the water hammer to occur. I used a stack of old pennies to prop up the ends of the radiator. Be careful as they are probably heavy, may require two people. If this doesn't work, they sell vibration dampeners that can reduce the effect of the water hammer on the pipes. This would go in-line with the supply piping so a plumber or if you have the know-how you can install yourself.



I also had spitting at the shutoff valves and steam vents. This was happening because the system pressure (even at 0.5psig boiler operation when operating for a long time) was too high due to improper sizing of the steam vent orifices. Some of the vents didn't work or it took very long to get air into the radiator due to being undersized and didn't release enough air. I ended up replacing ALL the steam vents with Maid o Mist after trials with other products. I tried using the Maid o Mists in combination with steam vents from other companies and found it was a waste of time because I couldn't control how they operated. I love the Maid o Mist vents because it really allows you to fine tune and tweak the system the way you want it to work. After I replaced all the steam vents and sized them properly to minimize the hydraulic restrictions, the spitting went away and the boiler worked much easier to fill the system with steam. The one issue now is some vents release a lot of air if the pressure builds up, but no water spitting. I need to tweak the orifice sizes seasonally depending on how long the boiler is on to make it easier for other radiators to release the air and minimize the noise at any one location.



It is also important to understand how the supply/return piping between the radiators and the boiler are connected. I have what "could have been" a two zone setup because there are two independent supply/drain lines and were interconnected at some later point in time when the new boiler was installed. The first "zone" only has two radiators on the loop where second "zone" has five on that loop. The supply/drain lines for each zone are interconnected near the boiler. I currently run both zones as 1 zone therefore proper vent sizing was critical to make them both work together. To make my system work the way I wanted it to, I needed to increase the orifice sizing on the vents on the two radiators in the first zone to make sure the airflow was great enough to draw the steam there at the greater rate because the zone with 5 radiators and 5 air vents was competing as the "path of least resistance" for the steam to enter. I also needed to provide restrictions to radiators (i.e. near the thermostat) to allow them to fill more slowly and allow the second floor radiators to heat up before the system shut off.



One off-topic thing I learned is that using double reflective "denny foil" like the kind used for wall/attic insulation taped to cardboard and placed behind the radiators not only looks cool, but it literally stops almost all heat from getting absorbed into the wall. Don't use aluminum foil as it degrades over time and eventually the effect wears off. I've noticed a huge difference in radiator performance now that we are not heating the garden! The cardboard was free, I picked up a roll of dennyfoil from the local plumbing contractor store for $50 and I had enough to do all the radiators and have plenty to spare.





I'm no expert on the subject matter, but I hope my findings can help.

Mike