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Questions regarding the main vent and auto water feeder that cuts off the boiler every 10 minutes (23 Posts)
Questions regarding the main vent and auto water feeder that cuts off the boiler every 10 minutesJust finished reading We Got Steam Heat. Wow, it’s a great read. I also bought The Lost Art of Steam Heating, which will take more time to study. I’ve begun to explore my single-pipe steam heating system and thus far have come across two questions: (1) where is the second main vent (if any)? (2) what’s up with the auto water feeder cutting off the boiler every 10 minutes.
To back up, I bought the home 15 years ago and right away converted from oil to gas. The system worked well enough. I figured out how to reduce knocking by tilting the radiators. The system does heat up slowly and some rooms are always colder than others. I thought that was normal, until I came across this website and read the book.
Question 1: the main vents. My system has two mains: The insulated main is 18 ft. and feeds 5 risers; the other main is 33 ft., uninsulated but is wrapped in a chute with grating on the side that allows some heat to warm up the basement. This uninsulated main also has 5 risers. I have 13 radiators (6 on the first floor and 7 on the second and I’m not quite sure how the risers match up with the radiators). I could not find any main vents in my initial survey of the piping. A fairly knowledgeable plumber said they should be at the ends of the main, but he also could not find them. I was beginning to believe the system must not have them. Then I remembered that seller of the house was the estate of an old plumber. The plumber might have been one of the Deadmen himself. How he could he not install main vents? Then I found a main vent covered with dust inside the end of the chute, after the last riser and right before the main turns into the return. But why did he seal the main vent into chute, which is difficult to take apart? After more careful examination, I noticed several screws on the side of the chute and voila, a small cover comes off and allows easy access to the Dole 4A main vent. After at least 15 years, probably 20 years, this vent still appears to work. It’s very quiet but I can feel hot air coming out of it at the beginning of a heating cycle. I have had no luck finding a vent for the insulated main. Attached are pictures of the ends of both mains. Could it be that the second, uninsulated main lacks a vent and that the air is vented through the radiators upstairs?
Question 2: Is it desirable for the auto water feeder to shut off the boiler every 10 minutes? The oil to gas conversion did not include an auto water feeder for the Peerless gas boiler (61-05-STDG-S). I got tired of checking and adding water myself and had an auto water feeder (an ITT McDonnell Uni-Match Universal Waterfeeder) installed separately. A label next to the on-off switch of the boiler says the following:
“Water level proving relay. The relay in this box will turn the boiler off every ten minutes during the heating cycle to allow the water level probe control to verify the water level.”
And sure enough, during the firing cycle, the boiler will abruptly shut off and restart a few minutes later. One plumber says this is inefficient. Another says he’s never seen such a 10 minute cut-off device. A third told me not to worry about it. It seems to be inefficient for the boiler to cut off mid-steam for the water level check. Is there a way to change the interval from 10 to say 20 minutes?This post was edited by an admin on April 14, 2014 11:31 AM.
The auto feeder from hellMost auto feeders are the work of the devil, but the one which pauses everything every 10 minutes is especially evil. It only has a benefit in a badly-piped (not by the instructions) boiler, where the water can be blown out of the boiler into the rest of the system, causing a low-water condition.
If your boiler is well piped with both risers, a proper header,, and has been properly skimmed, then you will have no problem with an unstable waterline. In that case, choose another LWCO without that feature. In any case, I feel that the auto-feed should be valved off most of the time, and the boiler water-level checked every week in person. If you have low water more than once a year, then there must be a leak somewhere.--NBC
there may be a away to shut of that functionI have not looked in the manual for your model but some can have this function bypassed. As for being tired of adding water, have you checked that under the floor pipe to see how big the leak is in it yet?Cost is what you spend , value is what you get.
cell # 413-841-6726
auto feederNo reason for this 10 minute auto check timer garbage. My guess is that someone had a water surging problem and instead of properly skimming boiler, they just put a timer so it wouldnt surge and feed water into boiler when it didnt need it. Judging by the pics of that glass gauge you have to skim that boiler and possibly add some surgex or surgemaster. Notice that the glass is extremely dirty above water line. I would fix the problem with the boiler shutting off every 10 minutes for a few minutes before adding any vents on main. Have you ever seen boiler make steam pressure on gauge?
Reason for 10 minute shut-offI am not commenting if I like or dislike the 10 minute run time but the reasoning behind it. In all honesty there is not need for it on the atmospheric gas boilers due to making steam slower. The need was thought yo be needed on the oil boilers due to making steam very rapidly.
Here us the reason behind it, foam. When a boiler is foaming the probe will still operate as it is in water.nit could cause dry fire. The delay allows the foam to collapse and/ or allow water to come back to the boiler.
Questions about water and metalThank you all for all the excellent insights. I will ask a knowledgeable plumber to replace or modify the auto water feeder to eliminate the 10 minute cut-off. As for leaks, yes, my radiators upstairs sound like a symphony of hisses, whistles, gasps and sizzles. I thought the sounds were normal and ignored them until I noticed water damage in the ceiling on the first floor. The roofer came and said it was not a roof leak. It was a radiator leaking. I've been examining and fixing those radiators and sealing off all points where water leaks out. As for leaks in the return pipes, I have not noticed any. About 70% of the return pipes in basement are visible. They're rusted on the outside but don't appear to be leaking. The other 30% is covered up but I haven't noticed any water damage.
Thank you for the tip on skimming. One of the reasons why I haven't been able to keep track of water level is because the glass is hard to see. What does it mean to see the "boiler make steam pressure on gauge"?
As I think about the water flowing through the system, I have several related questions:
Question 3: Should the water supply flowing into the boiler be cold water or hot water (from the hot water heater)? Click here to see the answers in a separate post (http://www.heatinghelp.com/forum-thread/150467/Should-the-water-supply-flowing-into-a-steam-boiler-be-cold-water-or-hot-water)
Question 4: Should a backflow prevention device be installed to prevent water from the boiler from flowing into the cold water supply? Click here to see the answers in a separate post (http://www.heatinghelp.com/forum-thread/150468/Should-a-backflow-prevention-device-be-installed-to-prevent-water-from-the-boiler-from-flowing-into-the-cold-water-supply)
Question 5: Should the supply valve be brass or iron? Dan writes that the old steam system were all iron because copper pipes give off oxides that are more corrosive. Recently, I had to boil two radiator air vents in vinegar and found that the solution turned turquoise, a sign of copper oxides. My system is entirely iron except several newer radiator supply valves are brass. I’m wondering whether I should have gotten non-copper supply valves for those radiators. I do not even know if such valves exist. (My older radiator supply valves are all painted but some have rust, which leads me to believe that they are iron).
Question 6: Should the “pigtail” be made of iron or brass? On the subject of metals, a plumber once told me that the pigtail on my boiler is made of iron or steel and that he would recommend replacing it with a brass pigtail, which would somehow make the pressuretrol work better. Not sure what he meant, but does that make sense?
Thank you again for all your help. Apologies for originally posting this message as a block of text -- I've added the paragraphs and headings to make it easier to read.This post was edited by an admin on April 18, 2014 12:54 AM.
FontsAs I tried to reformat the content of the previous posting, I noticed that the font options -- bold, italics, and underline do not seem to work.
Question for you....Hi! looking at your pics, my first question to you is, what is your pressuretrol set to, and what do you see indicated in the gauge? From the one photo you posted that shows your gauge, it looks like it is registering pretty high...could be a clogged pigtail due to crud in the water.
Second question, when the boiler shuts off in this 10 min cycle, do you hear the autofeeder kick on and hear water going to the boiler...or is it possible that the pressuertrol thinks it has hit a high due to a pigtail clog, and has shut it down due to a perceived high pressure?
Lastly, is your thermostat a programmable thermostat? If so, is it set through the pro settings (not info provided to most homeowners) to cycle only once per hour? Default settings for "most" (ie any I have seen) is more than 1 cycle per hour.steam newbie
My Pigtail is crooked, iron and probably clogged.Moneypitfeeder, you ask excellent questions.
1. My pressuretrol is set to the minimum -- cutting in at 0.5 psi. The gauge reaches 6 psi during firing and settles at about 1.5 psi when the system is cold. If the radiators are open to the atmosphere, shouldn't the internal pressure be at 0 psi when the system is cold? If that's the case, my pigtail could be clogged. In fact, my plumber today said he will replace it with a brass pigtail.
2. During a recent heating cycle, I timed the boiler and it would shut off for 10 minutes and pause for about 90 seconds and fire up again for 10 minutes. Over the course an hour, the boiler fired up 5 times. I did not hear the water feeder add any water during the pause periods. It appears that, even with the dirty pigtail and high pressure in the gauge, it is the water feeder's 10 minute timer that is dictating the firing cycle. [Btw, I found the manual to the Uni-Match water feeder on this website, but I can't tell if I can change the settings to increase the interruption interval: [url=http://www.heatinghelp.com/files/posts/4346/Uni%20Match.pdf]http://www.heatinghelp.com/files/posts/4346/Uni%20Match.pdf]
3. I do have a programmable thermostat (Lux 1500). I checked the manual for the first time in 10 years. The manual says my system should cycle on about 3 to 6 times per hour, but is defaulted to twice per hour. It also allows adjustments to the temperature swing of +/- 5 degrees F. It is said that a smaller temp swing produces more constant room temperature. A larger temp swing saves more energy. I am not sure what my situation calls for. Ideally, I'd like to have constant temperature (b/c I feel that it usually gets a tad chilly before the system fires up) and energy efficiency.
Thank you!This post was edited by an admin on April 19, 2014 11:23 PM.
OK...Hi, is it warm enough where you are to shut the boiler down for the season? I personally would not be operating a steam system without the protection of a pressertrol or vaporstat. It is apparent from your settings that it is not shutting the boiler down when the pressure is building/ or the gauge has been damaged by gunk or pressure and is not reading correctly. The gauge you have in the pic is an old vacuum gauge, that's why it has a negative side. I would recommend getting a new gauge, and making sure that your plumber protects it with the pigtail also, if you search here under tree or menorah I believe you'll see plenty of examples where both the stat and gauge benefit from the pigtail.
I would see about removing that relay, I have a lwco that's automatic, and do not have a silly every ten minute shutting the boiler down relay. My lwco works just fine, I've heard it kick on once or twice this heating season, and add some water.
Steam systems are meant to cycle 1, not more than 2 times per hour. Thermostats can cause a boiler to short cycle, but mispiping near the boiler is also a probable suspect too. I do think you need a thermostat that is meant for steam.
You probably have an old vapor/vacuum system, which means they are very fussy about high pressures, and will not behave as they should. Get the pressure down, to ounces not pounds, vent the system, and it will behave much better. You should consider a vaporstat, (it controls lower pressures than the pressurtol does)
Hope you get your system sorted out!steam newbieThis post was edited by an admin on April 22, 2014 7:22 AM.
Sorry...Some answers to your original questions:
Pipe your pigtail in brass, it will be less likely to build up crud.
The unvented main really needs to be vented, and you should check out some of Gerry Gill's work on venting on this site. I believe you need quite a bit more volume, but I don't know the specs for the Dole vents. A lot of us here go with Gortons for mains. What that will do (if you increase the volume of venting) is speed the cold air out of your main lines by reducing the restrictions, to allow the risers and radiators to heat faster. Since steam is always trying to turn back to cold water, the quicker you get the heat to your rads, the more efficient your system is.
There is some debate even on the wall on water supply, but from all the old books that I have read, if you pipe to the fresh supply (cold from the main house supply) to the return, it mixes with return water and is safe to enter the boiler.
I had never thought about a backflow preventer on the supply line, but after reading your question, I wonder why they aren't mandatory? Makes perfect sense, although I don't have one....
All of my supply valves are brass, for what its worth.
As for: What does it mean to see the "boiler make steam pressure on gauge"? You should be able to see the needle on the gauge building (moving) as the boiler builds pressure. Mine, also a vapor system hardly flutters a low pressure gauge. You should be more concerned with the sight glass, you can remove it and clean it, then observe what your water line is doing during a heat cycle. If it is just "breathing" or moving up and down a small bit, then good to go, if it is bouncing madly, then you have oil in your water. Oil in your water will produce heavy wet steam that is less efficient at heating.
Lastly, could you step back from you boiler, and post some pics of you "near boiler piping"? IE, we need to see the pipes coming out of the boiler and going to the headers.steam newbie
Pigtail installed and moreHi Moneypitfeeder, thank you so much for your analysis. I did not know how dangerous it was for my boiler to be operating without an effective gauge and pressuretrol.
Yesterday, while my plumber was fixing some radiator leaks upstairs, I asked him to replace the iron pigtail with a brass one. The nipple that connects to the pigtail and pressure gauge was almost completely blocked by chunks of stuff. The attached picture shows tube with some of the chunks already removed. It was like a clogged artery. My plumber decided to replace all connecting nipples with brass ones. He used a longer nipple because the new pigtail is a little bigger and would otherwise rub against the boiler when rotated. Hence the gauge protrudes a bit more from the boiler.
He then raised the pressuretrol setting from 0.5 psi to about 4 psi, and lowered the differential from 2 to 1 psi. I did not want to argue with him about the pressure level. He has not heard of Dan's book and keeps saying he has 45 years of experience, but I will lower the pressuretrol setting back to 0.5 psi.
Now, the pressure gauge shows -4 psi. A vaccuum inside my boiler? Methinks something is wrong with the gauge.
The water level in the glass is now slightly above the blackline. Before the pigtail was replaced, I had cleaned the glass and noticed that the water level was about three inches below the black line. I thought the waterfeeder was supposed to feed the water to or about the black line, so I manually added water -- but the water level in the glass did not budge. The addition of water, however, caused violent water hammers that we had never before experienced. The first radiators at the ends of the mains also began to spit water. I figured it was violent wet steam and promptly drained water from the boiler. The water hammer ceased as did the water spitting in one of the radiators. Another radiator continued to spit some water, and the plumber added a nipple to raise the vent higher. Spitting has also stopped there.
After the pigtail was installed, I noticed that the water level in the glass is now much higher. Not sure what this means.
There are lots of variables at play, and I am going to work on them.
First, I will need to skim. It's very apparent that the system is dirty b/c it hasn't been skimmed in many years. It's been drained but as I've learned recently, draining's not the same thing. (http://www.heatinghelp.com/forum-thread/150462/Skimmer-valve-failed#p1334570)
I will also find a more knowledgeable plumber to assess the situation and do the following:
1. Add vents to the mains.
2. Rebalance the vents on the radiators. I have a mishmash of USAVs, Hoffmans, Doles, Gortons, Flairs upstairs from different eras.
3. Repair or replace the LWCO to eliminate the 10 minute cut off.
4. Look at the gauge and pressuretrol to see what needs to be done there.
Again, thank you for your insights. Studying these boilers is kind of addictive. If you get a backflow preventer, be sure to get one that's lead free. Mine is not, and doesn't make a big difference because my other pipes are old. See (http://www.heatinghelp.com/forum-thread/150468/Should-a-backflow-prevention-device-be-installed-to-prevent-water-from-the-boiler-from-flowing-into-the-cold-water-supply)
Pictures of pipesI've posted pictures of the piping around the boiler into a separate post along with a question about the Hoffman loop. I figured it might be easier for folks to focus on that one problem as opposed to the myriad of issues we've got going here. :-)
Re-calibrate gauge and mount it on PigtailIf you look at your pressure gauge, there are a couple tiny screws on the face, just below the dial. You can re-calibrate the gauge to "0" using those screws, when the boiler is cold and there is no pressure in the system. Also, your plumber should have put the Tee on the top of your pigtail and mounted the pressuretrol and the gauge next to each other to help protect the gauge from steam as well. As far as the water glass is concerned, there are a couple things you need to check out. If you add water and see no change in the sight glass, in all probability, the port at the top and bottom of the sight glass that mounts to your boiler may also be gunked up like your pigtail was. When you drain the boiler, you need to take that apart and clean it out. Also, if you know you need to skim the boiler because the water bounces enough for the auto water feed to add water, you need to skim the boiler and when done, lower the water level down to the line that marks your NWL (Normal Water Level).
Blow-downI wanted to add you should have the boiler "blowndown" after seeing that much mud where the pigtail was. Skimming removes oil that is floating on the top surface of the cold water, but blowing down the boiler will remove the heavy sediment. Blowdown the boiler, fix any piping issues, and then skim to remove any oil that was there, or was added by any piping modifications such as adding the main vent to the unvented main line.
The gauge really should be moved up so that it is not receiving boiling water directly to it, the pigtail is a siphon loop which protects those safety devices so that they can work accurately.
Your pressertrol really needs set properly. (If you have a ptroll that says "Cut In" on the front scale) try to set to, .5 cut-in and 1 on the differential wheel. The screw on top is to adjust the cut-in setting, the diff wheel is behind the cover and is a large white plastic wheel, and see if your rads upstairs stop hissing.
Also, you mentioned that you added water to the boiler, and the sight glass water line did not change. Try removing the glass again, and making sure the piping from the boiler to the glass is clear (you can use a piece of coat hanger or something to push thru). There has to be a blockage if the line doesn't change when water is added or drained.steam newbieThis post was edited by an admin on April 24, 2014 7:42 PM.
Blown down and skimmedExcellent suggestions! I "blew down" the boiler by draining the hot water from a drainage spigot at the bottom of the boiler (and another spigot at the bottom of the glass gauge). The water flowed slowly from the bottom spigot and much more readily from the glass gauge spigot. Then, I opened the two nipples connecting the glass gauge to the boiler and found them both substantially blocked by a reddish colored claylike substance. Cleaned both. Then I filled the boiler, and the water level in the glass gauge responded instantly.
I heated up the water, and proceeded to skim from the back. At first, nothing came out of the drain. I added more cold water so that the water level was well above the skim valve and still nothing. I stuck my finger into the skim valve and realized that after 15 years of never skimming, that valve was clogged with a black substance that feels like pond mud and smells like the tar that plumbers brush on pipe joints before screwing them together. I used the back of a spoon to pry loose the muck and out came the hot water. At first the water ran very dark and with oil slicks on the top (like pictures from the Exxon Valdez in Alaska). With the boiler firing, I skimmed for after about 30 minutes, until the water was almost clear and the tar smell was gone. I felt it was impossible to get the water completely clear (there's a light reddish tinge). The hot water from the boiler had completely cleaned out the skim valve. Then I drained the boiler a second time. Again, the water ran slower from the bottom spigot than the glass gauge spigot. I poked wires into the bottom spigot but could not detect any blockage. There could be more particles further inside at the bottom of the boiler, but should I be worried? As a matter of routine, when do I need to skim again?
Also, I noticed that the device causing the 10 minute interruption in the firing cycle is not the automatic water feeder or LWCO, but a separate time delay relay in a metal box. The Zettler AZ941-1CT-24DE time delay relay controls the power to the LWCO. There's a sticker that says "OFF TIME FIXED" and "ON TIME FIXED". I'm assuming that means the 10 minute on-off interval is fixed. As Jason noted on 4/11, this device was likely designed for oil boilers. The company that installed my Peerless gas boiler was a primarily oil heating company and so they added this time delay relay as a matter of routine.
The question is: how to disable it?
I haven't found any instructions for the Zettler device online (only specifications). I've asked two plumbers and neither have ever seen it. Would I need to call an electrician? I'm asking another plumber (one who's listed on this website) to come over next week and look into balancing the air vents and the pressure gauge. I'll ask him too.This post was edited by an admin on April 27, 2014 1:17 PM.
pesky interrupterHave a look at your boiler installation manual online, and restore the wiring to the original configuration.
That interrupter was probably a bandaid for the lack of cleaning/skimming. The fact that it reduced the system efficiency was good for the oil company as well!
Get your main venting sorted out during the summer, and be generous with the vents, as the balance of steam arrival in each becomes more perfect as the resistance to the escaping air gets closer to 0 (one ounce back pressure).--NBC
Skim and Drain PortYou may need to skim that boiler several times before the water in the glass stabilizes when the boiler is running. There should be no more than half to 3/4 inch bounce in the glass gauge when making steam. If it is more than that, that's a good indication the water in the boiler is still contaminated. It may seem futile but if you skim several times, you will get there. The key to a good skim is to allow the water to trickle out of the skim port very, very slowly, maybe a gallon and hour. That keeps the oils from being mixed into the water by turbulence. It stays on top of the water and slides out the skim port. Start out with the water hot, like after a heating cycle. Once you see the water in the sight glass stabilize, you only need to skim when you see it start to bounce a lot (which should be nearly never) and when you have any repairs made to the steam pipes/returns as that will introduce new oils. As to your slow running boiler drain, I'd try to open it regularly for a few days and see if it cleans itself out. If not, the next time you completely drain the boiler, I'd take that spigot off and clean out the opening and the boiler mud leg. Whenever you introduce new water into the boiler, run it until it starts to make steam to burn off the excess oxygen. We're coming to the end of this heating season so you'll want to try to do these clean outs/skims while you still need a little heat.This post was edited by an admin on April 27, 2014 7:51 PM.
UpdateOver the past two weeks, with the help of the Steam Doctor (whom I found on this website), we've been able to disable the 10-minute timer delay relay, and install two main vents (both Gorton 1s). One of the main vents is entirely new and taps into the main pipe. The other replaced a Hoffman 4A. Aaron (aka Steam Doctor) curled this vent back a bit and extended it further up to protect it against water.
All of the radiator leaks upstairs have been fixed. The defective radiator vents have been mostly upgraded. Gorton 4 is the new standard size for all radiators on the first and second floors. I've also skimmed the radiator a second time (yielding a little bit of black oil residue).
From a cold start at 70 F, the last radiator on the second floor now heats up in 20 minutes compared to 30 minutes prior to the repairs. Some of the radiators with bigger vents heat up much faster -- 12-15 minutes. Note, it takes nearly 9 minutes to for the water to boil. Thus the steam travel speed has been reduced from 21 minutes to about 11 minutes. This system is also nearly silent. No more hisses and steam whistles.
I'd like to thank everyone for your helpful input. It's been an education. If every part of home improvement could be this much fun.
Actually, I have one more task ahead. I need to re-insulate my mains. I'm planning to use 1.5" thick fiberglass for the 2" mains and 1.25" risers. For the joints, elbows and tees, which have diameter as thick as 2.5"-3", I am planning to use bigger fiberglass insulation tubes (2" thick) and cutting them to fit. Does this sound feasible? My local plumber store does not have pipe insulation thicker than 1", so I'm thinking about getting it from buyinsulationproducts.com/. Do I need PVC tape or is duct tape sufficient?
Again, thank you so much!
One more thing to do:Get a good low-pressure gauge (valworx.com, 0-3 psi.), and put it on a manifold with the pressuretrol, original gauge, and itself. This will tell you what is happening in your system, especially if you need to add more main venting. As the steam is made, and begins to push the air out of the main vents, their resistance/capacity can be seen as back-pressure of venting, which should be no more than 2 ounces. Your steam arrival time seems slow to me.--NBC
Another, One more thing to do.You need to have your gas pressure checked at the test port on the gas valve it should be 3.5" WC. That may be the reason for a long cold water to steam time.
A couple more answersDo get a "Backflow preventer", you don't want to be drinking your boiler water do you?
Hot water is used on big commericals boilers. The tanks are set on high heat and get the minerals out and an "Air Separator "is used to get the iron eating oxygen out. Much easier to change a hot water tank than a boiler and it's piping.
Huh?First off, how would a 100,000 btu oil fired boiler holding 12-14 gallons make steam faster than a 100,000 btu atmospheric gas boiler holding 10 gallons? Doesn't sound plausible to me.
The 10 minute interrupt LWCO is designed for poor water conditions, nothing else. Foaming is caused by dirty water or, excessive PH or too much water treatment. Personally I would remove that and install a standard probe type LWCO such as the hydrolevel safguard 400.
This is a 24V product and should work with your system but have a pro confirm.
As far as how long it should take to steam from an ice cold start my system generally takes 20-21 minutes to get steam to the radiators. Again this is from an ice cold start after sitting for a day or 2. During the heating season when it runs often it's more in the neighborhood of 2-3 minutes.Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. Using Rectorseal Steamaster water treatment to greatly reduce corrosion in the boiler.
Steam system pictures updated 6/5/14.
https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#This post was edited by an admin on May 11, 2014 1:16 PM.