Noise again...

VickiS

I have a few questions for you all this morning...



A couple of weeks ago you guys helped me get my boiler unflooded.  Once I'd gotten the water level back to the correct level, the system was extremely quiet.  Radiators that had been hissing and spitting no longer were, no more banging pipes.  That seems to have changed in the last week...while things are not as noisy as they were, the pipes have gone back to making popping sounds (but nothing like they had been doing when I thought they were going to fall off the walls) and a number of the radiators are now popping and hissing again and just very loud.  I've also noticed that the pressure in the boiler seems to be higher again.  When I was having the flooding problem, the boiler was showing about 5 psi.  I turned the pressuretrol back to 2.5 point (it was set originally at 5), got the water level back to the correct level and the boiler then showed a little less than 2 psi when it was running.  Now it's consistently at 4 psi but none of the other settings have changed so I'm not sure what's changed to make the pressure go back up again or why the popping and hissing sounds have started again.  Any thoughts on what might be causing this are greatly appreciated as I'm having a hard time sleeping due to the noise again.



Another question I have is that I know the steam pipes should be insulated.  Does that include the mains and any branched pipes off it in the basement...or is it really just the mains where the primary concern for insulation is?  I have about 22' of uninsulated pipe in the basement that goes to a radiator in my dining room...it's a 2" pipe branched of the 4" main (I think those are the diameters of the pipes). 



When removing a radiator permanently from the system, the pipe should be cut and capped as close to the main source as possible, right?



Sorry for the randomness of the questions.  I actually have one more but I need a picture for that one.  As soon as I get it, I'll post that question as well.  I'm trying to understand how the main vents work...or actually backing up further than that, what is considered a main line because what I thought was a main line might not actually be one, but I will be back with more details on that question.



Thanks in advance for the help.



Vicki

nicholas bonham-carter

Return of the gremlin

The pigtail could be plugged up, allowing the pressuretrol to overshoot the upper limit, because it can't feel the pressure. With the boiler switched off, the wiring on the pressuretrol must be disconnected, and then pressuretrol and pigtail removed. Check the pigtail with a magnet, and if it is steel, replace it with a brass one. If the magnet shows it to be brass, then wash it out thoroughly, and put everything back together.

Take a picture of your boiler piping and post it here before you insulate with fiberglass., as that may be part of the problem.--NBC

Rod

Pressure Gauge

Hi Vicki-  I was just looking over the pictures you posted before and I can't seem to find a pressure gauge. Do you have a pressure gauge? AlsoI emailed you some info on replacement parts for your LWCO, did you receive my email?

- Rod

VickiS

Email

Hi Rod -

I somehow missed your email when it came it.  Thank you for pointing it out and thanks so much for the information.  I've been keeping an eye on the leak from the lwco and I don't think it's a change I need to make immediately but I will keep the information on hand in case the leak gets worse.



The pressure gauge I was referring to was the one that is directly attached to the boiler.  Funny, it's not in any of the pictures except for this one and it's mostly hidden behind that curved pipe that is to the left of the pressuretrol.  Sorry for the quality of the pic.  The gauge is that round thing behind that pipe.  I know you recommended adding a 0 -3 psi gauge in one of your other posts but that is not something I have been able to do yet.  From what I've been reading that the gauge on the boiler isn't really accurate, I've been using it as more of a checkpoint...figuring if it stays about the same level when the system is running smoothly that the pressure is okay.  I'm concerned that the pressure has gone from 2 after I unflooded the boiler to now 4 which seems to correspond to the increased noise and the hissing/pinging radiators.  I can't figure out why the pressure would have increased...nor why the system has gotten noisy again.  I've been trying to blow down the lwco more often because the water is dirty in the site glass.



I'm not sure what to do to get the system to quiet down again.  Some of the rooms get really hot now.  Oh that reminds me of another question...we have the thermostat set at 62 but I've noticed that the system does not cut off until the temp reaches almost 68.  It was doing this when I was having the original trouble with too much water in the system.  Once I drained it, the temp on the thermostat was within a couple of what we had it set at...so if we set it at 62 it would cut off by 63/64....so that also seems to be contributing to why the rooms are over heating because the thermostat isn't kicking off when it should.  Any thoughts on what might be causing that to happen again?



Steam really is a good system right cause it sure is giving me a headache these last few weeks.    I'm asking that tongue in cheek because I know it is, I'm just having a hard time figuring it out.



thanks! 



Vicki

VickiS

Re: gremlin return

Hi Nicholas,

Here are a few pics of the system.  There are more in this post although I'm not sure they will help much....http://www.heatinghelp.com/forum-thread/142802/Knocking-pipes  I need to take some better ones which I won't be able to do until the end of the week.

The pigtail is the thing that the pressuretrol sits on?



Vicki

VickiS

Main line question...

I'm not sure if the two pictures I've attached here are enough to answer this question, if not I will get pictures of the entire room so you can see what is going on...



The first picture shows a picture of the boiler.  The mains head off to the right and left.  The one to the right goes thru the wall, makes a T and heads to the front and back of the house.  In this area is where I have the 22' of uninsulated pipe that is off the main line that is heading to a radiator (and maybe pipes to the 2nd and 3rd floor but I need to double check that). 



The main to the left hits the far wall and makes T.  The line to the right of that T heads to the back of the house, the line to the left of the T, continues until it hits the wall of the room that the boiler is in then turns left and heads along the back wall of the room.  So the 2nd pic is what things look like if you originally start out looking at the boiler and then turn 180 degrees so you are facing the other way.  My question is if this is a main line or something else because no lines come off of this pipe...it has the vent at the end and then the pipe goes down to the floor to the return pipe.  Is this part of the Hartford loop?  I haven't quite figured out what that is yet.



I just realized that the pipe is hard to see in the 2nd pipe...the one I'm referring to is the lower one that below the black one and runs right above the doorway into that back room.  There is a vent at the very end of this pipe and I can definitely hear it working now when the system is on.  I'm curious what this line does as it doesn't seem to have branching pipes leading to any radiators...it seems to come off the boiler, go around the room and then head to the floor.



Vicki

Hap_Hazzard

That's a dry return.

It's just there to carry the condensate over to the drip that goes to the wet return. It looks like it's above the A dimension, and the main vent is right at the top of the drip, which is okay.



The problems are located closer to the boiler.



You have, in effect two or three headers, but no vertical rise that's more than about 12". Without a straight, vertical rise of more than 24", preferably right from the boiler, you're going to get wet steam, and the harder it's steaming and the more oil there is in there, the wetter it's going to be.



Since you recently drained a lot of water, and the noise went away, I suspect the oily gunk that has accumulated in your radiators and piping has found its way back to the boiler and it's making the boiler surge and foam and splatter water up into that header, where it easily sprays up into the next level and the next and out into the mains. That crazy-looking equalizer isn't helping matters much. They should have put the reducer at the water line instead of at the elbow, and they shouldn't have run it horizontally until below water line. You've got a horizontal pipe filled with steam within the A dimension. That's a Bad Thing.



Your system could really benefit from some changes in the piping, and, ironically, there's probably more than enough pipe and fittings there to do it right just by changing how they're connected, but right now I think you would be able to see a dramatic improvement in your heating and the noise level if you skim the boiler. You might need to do it every other weekend for a couple of months before it stays clean, but if you're not afraid to get your hands dirty you can do it yourself. Just let us know if you're interested and we can talk you through it.

VickiS

Re: Dry return

Thanks for all the info.  I think I followed most of what you were saying.  Can you explain what the equalizer is and the reducer?  I'm not sure what those are or where they are in the picture.



As far as getting dirty, I have no problem with that.  I'm about to crawl into our attic this weekend which we discovered had a massive fire in it at one point...so charred joists and insulation will make for quite a mess...but that's another story in my house saga...



I've seen other posts about skimming the boiler but I have no idea how to actually do it.  If you wouldn't mind walking me through it, I would greatly appreciate it.  Thanks so much!



Vicki



I've been reading the We've Got Steam Heat book and I think I've figured out what the equalizer is...in my pic of the boiler, it's the sideways looking U piping on the right hand side of the boiler, right?  I'll have to take a look to see where it's actually connect back into the boiler because that must be happening on the backside of the boiler which I don't have a picture of.  I'm still not sure what the reducer is.

Hap_Hazzard

Careful in that attic.

I assume you know how to recognize asbestos, but old attics were often insulated with vermiculite (expanded mica), which often contains asbestos. If you come across any, don't disturb it until you've read up on safe handling procedures.



The equalizer is a pipe that runs from the header to the return leg of the boiler. It's purpose is to equalize the pressure of the generated steam pushing down on the water column, allowing the water to return to the boiler and helping to release the steam from the boiler. In the middle picture in your second post, it's the pipe connected to the right side of the header through the elbow with the reducing bushing in it. By reducing the size of the exit from the header, they reduced the amount of water that could be entrained into the equalizer. It would have been better to use a larger pipe and drop it straight down, then go horizontally to the return. Any reduction should have been made at or below the water line, but the diameter should not be less than what the manufacturer recommends.



There is an excellent article here on skimming your boiler. If you have any questions, you know where to ask. He mentions three chemicals that can be used to help clean the boiler. Of the three, I recommend the sodium carbonate, also known as washing soda. It's less caustic than lye, less environmentally harmful than TSP, and the alkalinity it adds helps to prevent rust, but try skimming without any additives first.

VickiS

Re: Skimming

Thanks for the article.  It looks pretty straight forward but was not at all how I was expecting skimming to be done although I'm not quite sure what I was expecting now that I've said that.  This isn't something I will be able to do until probably Friday but I have a couple of initial questions around what I was reading and the diagram shown....



- the skim tapping that the picture shows is some kind of hole that is on the side of the boiler?  is it normally plugged and I remove the plug to give the water the ability to drain out?  I don't remember seeing something like that on the side of the boiler but I've been very focused on the side that contains the lwco up til now.  I don't have any pics of the other side or the back of the boiler but I will take a look and see what I come with. 



- what does it mean by attach a full size nipple?  I understand that it's a way to allow the water to get out without running down the side of the boiler, I'm just not sure what it is or how to attach it.



- how do you control the temperature of the water so that it gets hot enough for the skimming purpose but not hot enough to produce steam?



I have a few others but they have to do with after the water has been skimmed so I'll wait on those for the moment.



Thanks!



Vicki

Rod

Check the Pigtail

Hi Vicki-

   Regarding your new problems as NBC mentioned, I think you first need to inspect the pigtail and path from the boiler to the pressuretrol to make sure no openings are restricted. When the boiler was flooded, there may have been some debris enter the port which that is now blocking the line / passageway. This should be inspected annually anyway as part of the annual servicing. If you want a list of parts necessary to renew this let me know and I’ll put one together for you.



Skimming - I don’t think this is a practical consideration at this point.  You would need to get the skim port opened and with an older boiler this would need to be done by a professional with the experience and tools to do the job. They are very hard to loosen when the boiler is new and after rusting in place over time are an absolute *&%$$##**  to get out!!

I’ve attached an Independence I& O manual. If you look on Page 8 in the manual, Tapping “L” is the skim port.

- Rod

VickiS

Re: Pigtail

Yes, if you could put a list together for me that would be awesome.  I will take a look at the pigtail.  What else is involved in checking the path from the boiler to the pressuretrol besides checking the pigtail for blockage?  Thanks!



Oh, and I see what you are referring to in the manual about the skim port.



Vicki

Hap_Hazzard

Skimming

Yes, the skim tapping will be plugged. You need to get a square socket and use a flex handle or breaker bar and break it loose. It's above the water line, so you don't need to drain the boiler. Since you don't want to go through that again, install a 1 x 4" pipe nipple with a full-port ball valve, then put that plug in the ball valve when you're not using it.



To control the water temperature, a lot of people just turn the thermostat way up and then tilt the rocker on the pressuretrol to turn off the burners. I like living on the edge as much as the next guy, but I just think it's safer to use a clip lead to bypass the thermostat and disconnect it to cut the burners. Besides, I'm lazy, so that last-minute sprint upstairs to turn down the thermostat, when I realize that that's the only way to shut it down without holding that rocker, doesn't appeal to me. I use an electronic roast thermometer with a long metal probe to measure the temperature. When you're skimming, you keep adding cold water, so the temperature stays just about steady with the burners going.

VickiS

Stepping back for a sec

I appreciate all the advice and I hope you guys don't mind if I step back for a sec to make sure I understand what the different troubleshooting thoughts are trying to do.



1)  Checking the pigtail for a clog is trying to determine if the reason that the temp is overshooting is because the pressuretrol isn't able to sense the temp correctly?  And because the temp is overshooting, the boiler keeps making steam, therefore building pressure and sending more thru the system which could contribute to the pinging and hissing that I'm hearing again?   



2)  regardless of whether 1) above is true or not, there is also the possibility that the excess noise is being caused by crud being on the water that the steam is fighting to get through, which is throwing junk into the mains which was the reason for the skimming suggestion...to clean the water up so that it's easier for the steam to get up to the mains?



3)  even if 1) & 2) are taken care of, I am still going to have problems because of the way the system is piped...because it's causing wet steam in the mains?





Those questions are all related to what we've been recently talking about.  I have a few others...



4)  is there any benefit to draining the boiler and getting as much crud out of it as I possibly can?  In my original post when the boiler was overfull it was suggested to drain thru...shoot can't remember what it's called but it looks like a nozzle that you would attach a garden hose to.  When we tried this, nothing came out and the speculation was that it was clogged and to drain the water thru the lwco...which worked to get the level down.  Should I go back and try to get that drain unclogged so that some of the crud at the bottom gets out and stops getting mixed around in the water during each cycle?  I know that doesn't address the oil and stuff that sits on top of the water which is the purpose of the skimming, I just wasn't sure if cleaning the stuff from the bottom would gain us anything.



5)  When doing the lwco blow down...that is done while the system is running, correct?  When I do this, I can hear the burning kicking on and off as the water level is fluctuating.  When I open the lwco the 3 times to let the water out, the water level jumps around and causes the burner to kick off...when I close it for tha 15 secs or so, the burner kicks back on.  Is that normal?



5a)  related to the blow down, this seems to reduce the water in my site glass somewhat...can I add water to the system at this time or because it's hot, I should wait to add water until the system cools down because we don't want to add cold water to the hot water?



I have more questions about the mains and vents but I will put those in a separate reply.  I think it would help me if I mapped out where my lines are and where all the radiators are attached and what kind they are.  Right now I can't figure out where some of my pipes are going.



Thanks so much for your thoughts!



Vicki

Rod

Answers to Questions

Hi Vicki- With regard to your questions-



Question #1- The Pressuretrol senses only pressure, not temperature. If the pigtail is restricted / clogged this means the Pressuretrol can’t get accurate readings and there fore isn’t responsive to the real pressure in the boiler.  The pigtail and piping needs to be checked and cleaned if necessary and annually cleaned and inspected.



Question #2 - Steam gets into the mains whether there is crud on the water or not. The problem is the quality of the steam. Take a look at the pictures of dry and wet steam I posted in another reply. http://www.heatinghelp.com/forum-thread/143161/How-does-wet-steam-behave

The difference between the two is that a tablespoon of oil was added to the boiler when it was producing dry steam and this increased the surface tension so that the steam now had to gather in larger bubbles to break the water’s surface.  The violent break through causes water droplets to be carried along with the steam and up into the mains.  This mixture of water droplets and steam is what we call “Wet Steam”. (as in the photo labeled “Wet Steam”)



Why is Wet Steam “bad”? -  Wet Steam is a mixture of 212 (plus) degree steam and 212 (minus) degree water. The water droplets in the wet steam tend to cool the steam which causes the steam to condense and turn make to a liquid.  You have to keep in mind that H20 (water) is very unstable as steam and it would much rather be liquid (water) than a gas (steam).  When this happens in the piping before the steam gets to the radiator the collapsing steam gives up the latent heat it is carrying and that heat never reaches the radiators to heat the room. It also makes noise!



Water Hammer- When a cubic foot of steam collapses (condenses) it instantly goes (volume wise)  from 1 cubic foot of steam  to 1 cubic inch of water. This creates a huge vacuum void and water (and water droplets) rush in from all sides to fill the void. The noises you hear are from the collision of water crashing together in the void.  Large bubbles of collapsing steam produce a “Bang” and small bubbles produce a “Click”

Here’s a link to a good video that shows collapsing steam and the noise it produces, (Be sure to turn your audio on)   http://www.kirsner.org/pages/WaterCannonVideo.html



  Our goal is having a system that produces dry steam.

This is accomplished by:

1. Having a good steam /water separator - this is the header pipe and properly configured boiler piping.

2. Having good boiler water quality - Reasonably clean water and low surface tension.

This is accomplished by the occasional cleaning of the system and be thoroughly skimming the surface of the boiler water to remove contaminates like oil



Question # 3 - That’s hard to answer. You do have problems with your boiler piping configurations though how much that affects the system is hard to determine.I would eliminate the other problems first and then see what happens.



Question # 4 - A thorough flushing of the boiler can’t hurt as it hasn’t obviously done in quite a while. The only thing I would be concerned about is that it really isn’t the time of year to do it. It may be better to see if you can limp through this heating season and address the issue of flushing and possibly replacing drain valves etc. in the spring.



Question # 5 - It is normal for the LWCO to turn the burner off when you blow down the LWCO. What is happening is the out rush of water lowers the float momentarily in the LWCO, and this cuts off the burner. This is an indication that the LWCO is properly operating.



Question # 5A - The small amount of makeup water will mix with hot water in the boiler so there shouldn’t be any problems with this. You just wouldn’t want to drain large amounts of water from a hot boiler and then add large amounts of cold water. Always bring the boiler water to the boil after adding new water to drive off the dissolved oxygen.



Mapping out your steam system is a really good idea. You might also want to get a 3 ring loose leaf binder and some 3 hole clear plastic sheet protectors . If you don’t have a printed copy of the I&O manual I would print out the manual from the pdf I sent you earlier and include it in the binder. The binder is also useful for storing articles on skimming, parts sources etc. might be useful to you in the future.



Skim Port- I’ve attached a photo of a typical skim port setup. Note the pipe cap. If you have small children around it is always a good idea to have a secondary backup/closure (cap or plug) on all drains on the boiler in case inquisitive young  hands happen to turn a valve handle. Having this “backup” could stop a tragic scalding accident. 



On removing the pipe plug from the boiler’s skim port- Again I would strongly suggest you get a pro to do this for you.



Pressuretrol/Low Pressure Gauge Piping- I’ve attached a pdf with drawings and a Bill of Material for this.  You’ll note it uses a Vapaorstat rather than a pressuretrol.

The fittings you may be able to get locally at a good plumbing supply store. I use McMaster Carr a lot as we lack a good supply store here locally in Maine and they are very reliable and ship parts the same day as the order was placed.



Planning- It sounds to me like things are slowly coming together for you. When you are new to steam, at first, it is pretty confusing but slowly the light bulb goes on and things begin to slip into place. At least that was how it was for me. I’d make a list of what needs to be done immediately to get through this heating season and a list what can be put off to a later when it is spring. You might also want to split the lists to what you need a pro to do and what you can do yourself. "We Got...." has suggestions on this.

- Rod



 



 

Hap_Hazzard

In addition to what Rod said,

I want to add that cutting off the burner is what the LWCO is supposed to do when the water level drops, and the off-on cycle you observed is exactly what you should expect every time you do this, and you should do it every week to ten days throughout the heating season. This is a critical safety test. There should be a conspicuous sticker affixed to the boiler jacket near the LWCO containing these instructions.



If the burners ever fail to cut out when you open the blow-down valve, it means the LWCO is not functioning, and if you were to lose water, there would be nothing to prevent the burners from firing under your empty boiler. At the very least, the boiler will be history. It could also burn your house down or explode.



But blowing down the LWCO is also preventive. Flushing the sediment prevents it from building up under the float and preventing it from sinking when the water level drops.

Hap_Hazzard

In addition to what Rod said,

I want to add that cutting off the burner is what the LWCO is supposed to do when the water level drops, and the off-on cycle you observed is exactly what you should expect every time you do this, and you should do it every week to ten days throughout the heating season. This is a critical safety test. There should be a conspicuous sticker affixed to the boiler jacket near the LWCO containing these instructions.



If the burners ever fail to cut out when you open the blow-down valve, it means the LWCO is not functioning, and if you were to lose water, there would be nothing to prevent the burners from firing under your empty boiler. At the very least, the boiler will be history. It could also burn your house down or explode.



But blowing down the LWCO is also preventive. Flushing the sediment prevents it from building up under the float and preventing it from sinking when the water level drops.

VickiS

Thanks Hap...

I appreciate you confirming things and your additional thoughts.



Since the systems to not have been properly maintained in the past, is there any benefit in me doing the blow down more frequently?  I'd had a brief discussion with the previous owner of the house about the system prior to purchasing the house and he indicated that he only flushed the water once during the heating season.  I had no idea at the time that was not how it should be done.



There is no information on the boiler anywhere, stickers or otherwise, and definitely no instructions on how to do things.



oh, unrelated to steam, you had mentioned to be careful of asbestos when in my attic...no worries there as right now there is no insulation at all in the attic.  So I get to look forward to climbing around over burnt rafters while spraying in insulation.  Should be a fun, and cold, Saturday. 



Vicki

VickiS

Re : Answers

Thanks Rod for all the answers.  It is greatly appreciated.  All your explanations, attachments and pictures are great and very helpful.  I'm going to take your advice and put together a notebook that contains all the information I've been gathering so I have it for easy reference.  Some things are slowly starting to make sense to me...but other things are just beyond me at the moment.  Like why a radiator that hasn't heated in the two months we've been in the house would suddenly start heating when I've done nothing to it.  It was behind a screen that needed to be unscrewed and I just hadn't gotten around to working with it.  I realized when I was standing in front of it the other day that it was throwing out heat.  So strange to me.  I've read so much talk about boiler size and radiator output that it has me curious as to what our house is.  I know someone commented early on about how big our boiler is, and we do have a big house, but  I'm wondering if the boiler is the right size...not that I can do anything about it.  Just curiosity on my part.    I know this boiler was installed within the last 10 years to replace what the previous owner says was a coal converted to gas boiler.  This is probably why the piping looks weird because the new one was put in and tied into the existing piping with as little changes as possible although that is purely speculation on my part.



Can you help me make the connection between the pressuretrol, thermostat and boiler?  Right now I am missing how the three interact together.  I know the thermostat is set at a certain temp and when the room reaches that temp a signal is sent to shut the heat down.  The pressuretrol registers the pressure in the boiler and when the boiler reaches a pressure that is higher than what the pressuretrol is set for a signal is sent to shut the boiler down.  What if the boiler reaches a pressure higher than the pressuretrol setting before the temp setting is satisfied?  The boiler shuts down but how is the temp then reached?  It would...or once the pressure in the boiler decreases it would kick back on allowing the temp to rise until it reaches the target temp?  I'm not sure I was able to coherently ask my question but hopefully you understand what I was trying to get at.



I have a question about vents that goes back to my previous posts from a couple of weeks ago.  You made a comment about them being shot and at the time I was a bit overwhelmed with the water hammering going on that I misread what you wrote and thought you were referring to the main lines.  Now I realize you were talking about the vents on the lines.  Are you thinking that I should replace those vents?  I've attached the pictures of the 3 vents I could find although there has to be at least one other one that I am unable to see at the far end of the system.  Vent 1 is at the end of the dry return, vent 2 is off the right main line that heads towards the front of the house, vent 3 is off 22' L shaped piping that comes off the same right main line.  There's another main line that heads left and towards the back of the house but I've been unable to find the vent for that one because I can't easily access the space where the pipe runs.



Vicki

Hap_Hazzard

Blow-down

I can't see any added benefit from doing it more frequently, but in the spring you should definitely take it apart and clean and inspect it. You're supposed to do that every other year anyway.

VickiS

Re: Blow-down

Cool.  Thanks Hap!



Vicki

VickiS

Regarding pipe insulation

Should all the pipes over the boiler be insulated?  They seem to only be partially insulated.

Rod

Function of the Pressuretrol & Thermostat

Hi Vicki-

   I’m trying to think of a good way to answer your question on thermostats and pressuretrols and what/how they operate.



Very basically a thermostat controls the temperature of the room (in which it is located)   and a Pressure Controller (Pressuretrol)  controls steam  pressure in the boiler. They are both “high limit” switches.  “High limit” meaning that when a maximum setting is reached, they switch the off the power (electricity) running through them.  



A thermostat is a just a specialized electrical switch that senses heat. It is a high limit switch which means that when it reaches a  maximum set temperature, it turns off.



A pressuretrol is just a specialized electrical switch that senses pressure.. It is a high limit switch which means that when it reaches a maximum  set pressure, it turns off.



*** For the burner to be operating,  BOTH the thermostat  switch AND  the pressure switch have to be  ON.  If only one of them is ON, the burner won’t be activated. (producing heat) ***



    Now let’s discuss boiling potatoes. To do so you place a pot (boiler) filled with water and a few potatoes on the stove above the burner.  You then turn on the gas to High so the water boils quickly. After the water has reached the boil, you turn the burner down to where it’s just enough to keep the water boiling.

     Let’s say we didn’t have a nice dial control with the settings  Off, Low, Medium and High and Marks in between the settings and just had an ON -OFF Switch.  Visualize what you would have to do to cook the potatoes with just an ON -OFF switch. You would have to turn the burner to ON and wait until you saw the water start to boil and then quickly turn the burner OFF so it wouldn’t boil over. You would have to repeat this cycle until the task was completed  (Task = the  potatoes are cooked)



  The situation is very similar in your steam boiler. There is a pot of water (the boiler) and a high capacity burner (large flame) controlled by an ON -OFF switch.  Like  boiling the potatoes  using just an ON -OFF switch, we could do the same with the steam boiler. We could turn the switch controlling the burner to ON and when the water boiled making steam, we could then turn the burner OFF. We would then repeat this cycle until the task was completed (Task = the house is warm)    Obviously standing by your boiler 24 hours a day, turning the switch On and Off isn’t very practical so we use a Pressure Controller to do the job of turning the burner ON and OFF.



    Let’s now discuss how the pressure controller (pressuretrol) and temperature controller (thermostat) operate in your heating system.  It’s a nice warm day with the sun shining through the windows. The inside temperature is 70 degrees and the steam system is off  because the setting on the thermostat is set to 68 degrees. As the day goes on and the inside temperature of the house begins to cool, when the thermostat senses that the temperature is lower than the set High Limit (68 degrees) it turns its internal  switch to ON which sends electricity to the burner and activates  the burner.

   Since the boiler water is cool, it will take some time before the water will come to the boil (like the potatoes) but once everything every thing is hot,  more and more steam is produced. If the volume of steam produced is greater than the radiators can use (when the radiators are cold they condense steam really fast  but as the radiators warm up they condense steam moire slowly) the steam pressure will build up and when it reaches the High Limit setting (typically 2 PSI) on the Pressuretrol, the internal switch in the pressuretrol turns to OFF. This stops the electricity going to the burner and the burner is turned off.   As we don’t want the burner to come back on as soon as the steam pressure drops just below the High Limit  Pressure setting (2 PSI), there is a “differential” function  built in the the  Pressuretrol which  means  the switch will stay OFF until differential setting is reached. (Typically on a residential steam boiler the differential setting is 1 ½ PSI below the High Limit setting.)  When the steam  pressure  drops to the differential setting, the internal switch in the Pressuretrol turns back to  ON and electricity is sent to the burner which turns the burner back ON.  

     This ON and OFF cycling of the burner by the pressuretrol would continue forever if the other control, the thermostat, wasn’t involved.  The steam  being produced by the cycling is heating the house and so when the High Limit setting ( 68 degrees) on the thermostat is reached, the internal switch in the thermostat turns  OFF the electricity going to  the burner and the burner  stops producing heat.  The steam system will stay off until the temperature in the house drops below the High Limit  setting on the thermostat and then whole cycle starts again.



   For clarity the above explanation as been greatly simplified.  Besides the thermostat and Pressure Controler (Pressuretrol) there are multiple safety devices (switches) that must be in the ON position for the burner to operate.  One example is the LWCO - If the boiler water is at a safe level, the switch will be ON, if the boiler water level is below the safe operating range, the switch will be OFF and the burner will not operate.



Short Cycling- You’ll hear this term now and then.  “Short Cycling” is when the burner is continually turned on and off by the pressuretrol in a very short time period.

This can happen if the boiler is grossly oversized for the system. It can also happen to a properly sized boiler in the spring and fall when the temperature are fairly warm and there isn’t a great demand for steam by the radiators.  You have to keep in mind that the heating system is designed to keep you warm on the coldest day of the year at your location so in the warmer months produces more steam than necessary.



Main Vents- The vents in the picture look like Hoffman #75 (or #76 is they are vacuum vents)

You can test their operation by using a strip of news paper taped to the end of a broom handle. Hold the strip up near vent hole at the top of the vent and if working properly you should see some movement of the paper when the boiler first starts making steam. The movement of the paper will stop when steam reaches it and the vent shuts.  The vents can be cleaned by soaking them in CLR (A household  product to remove lime deposits) for a few days. They can also be boiled in vinegar to clean them.  Unless they aren’t working, this is something you want to do in the spring when you don’t need to have your heating system operating to keep you warm.



DO NOT USE YOUR BARE HANDS to check whether the vents are working!!  Live steam is invisible and can give you a very Bad Burn!



Insulation- Yes it would help to insulate the piping near the boiler. However I would  hold off on that until you decide what needs to be done with the boiler piping. I would insulate any of the mains which aren’t involved and are likely not to need any modification. “Crash 2009" put together a really great article on insulation. I don’t have the link handy but you can look it up using  “Search the Wall”.

- Rod







 

 

VickiS

Explanation...

Rod,

Thank you so much for taking the time to write out that explanation!  You're explanation was great and I understand exactly what you were saying.  



Now the short cycling while I get what you are saying, I will need to think about some more before it fully sinks in.



I'll do some checking of the main vents to see how they are working and I will also do so mapping and measuring of the main lines while I am down there.  I'm still having trouble with how everything is laid out...the radiators at the front of the house get warmer significantly later than the ones on the same line in the middle of the house (at least I've learned enough now to recognize that they are on the same main line). Does that indicate that there isn't enough venting on that line?



And the piping on the 3rd floor has me totally baffled as I can see it going thru the ceilings on the 2nd floor but it is no where near where the radiators are located on the floor.



I was able to find Crash's information on pipe insulation.  That will take me awhile to go thru but it's great information.



Thanks so much for all your help!



Vicki

VickiS

System Map

I was able to map our system as best I could.  Sometimes it was hard to tell what the pipes were doing but this is what I was able to come up with.  Map1 shows how the pipes are laid out in the basement and includes the length of the mains.  I forgot to check the diameter of all the pipes although I know the ones coming directly off the boiler are 4" and the submain is 2".  I'm not sure if the mains are 2" too or a little bigger.  Map2 shows the layout of the radiators.  We are currently renovating the third floor of our house so a bunch of the radiators are closed off so I did a comparison with and without the closed radiators compared to the boiler BTU.  Not sure what it me tells but it's an interesting comparison assuming I did it correctly.  I took the total EDR x 240 x 1.33 to come up with the BTU.  There are two radiators on the 2nd floor that get really hot...both are off main 2...one is the first pipe to the left heading down the dry return, the other one is either the first or second pipe heading to the right.  Main 2 and the submain seem to heat much quicker than Main 1 although there is 1 pipe off Main 2 and one off Main 1 that remain cold, I think because they only supply heat to the third floor and those radiators are currently closed.  Would that make sense?



Could you tell me what types of vents these are?  The first one is at the very end of Main 1.  The dry return and submain both have one just like at the end of the lines although they are not raised up like this one is.  The second one is at the end of Main 2.



Thanks!



Vicki

Steamhead

The one on the left

looks like a Hoffman #76, and the other looks like an original-type Hoffman #6. Both are vacuum-type vents, which only work well with coal firing, and both have been leaking.

VickiS

Re: Vents

I guess I shouldn't be surprised by this.  Thanks so much for the information.



So the vents should be replaced.  What would be the recommended vents to replace them with?  The length of the mains come into play with this, right?  Because the goal is to get the steam to both ends of the mains at approximately the same time, right?  So a shorter line would have a slightly slower vent than a longer one?  Main 1 is 66' and has an offshot line near the beginning that is 22'.  Main 2 is 40' and has the dry return branching off near the beginning that is 25'.  3 radiators are sourced near the beginning of this dry return if that makes a difference.  Each of the 4 lines currently contain a vent.  Thanks!



Vicki