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  • #61
    Re: My boiler is short cycling

    The pipe in the second pic goes thru the bathroom wall but I don't see it from the outside. So, I'm not sure if it went up or down and if that is the pipe that return to the boiler.

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    • #62
      Re: My boiler is short cycling

      Originally posted by Masterplumb View Post
      You said if it was a clogged pigtail the boiler wouldnt start? I believe you have it backwards, if the pigtail was clogged the pressure-trol would never get a reading, making the boiler cycle LONGER and build up the steam pressure, most likely until the relief valve blew.
      yeah yeah yeah...the other way around.
      Who's on first?

      Also, referencing F & T trap on two pipe systems...I'm guessing you mean Hartford loop..(?)

      Comment


      • #63
        Re: My boiler is short cycling

        Originally posted by zuffy View Post
        Can I assume I don't seem to have a problem anymore? The air vents in the bathroom and master room are not hissing loudy anymore after the cleaning. Since changing the cph from the default 6 to 3 and then to 1 which is the correct setting for my steam system, the boiler have not been short cycling. The last time the boiler came on around 11:12am, it just came on at 3:23pm and stop at 3:43pm. The thermostat did not call for more heat.
        Sorry, I'm a bit confused. Did this post say the problem was solved.?

        If not, the discussion of main vents. If you have a one pipe system there, you may not have main vents, the radiator vents serving that purpose.
        sigpic

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        • #64
          Re: My boiler is short cycling

          [
          The thermostat is hardly ever an issue with cycling, its usually a pressure problem, i.e. the air cant escape from the vents fast enough and this will make the pressure rise faster then normal.

          www.heatinghelp.com

          This is right out of Dan Holohans book. Note the very first paragraph.


          Steam Problems?

          You are now reading a part of Dan Holohan's book, A Pocketful of Steam Problems (with solutions!) You can order the full text from Books & More. That way, you'll have HeatingHelp when you're on that next problem job!

          THE BURNER SHORT-CYCLES.

          The thermostat is out of calibration.If it is, the burner will be bouncing on and off. Make sure you use an ammeter when you're checking the calibration. Don't guess at that anticipator's setting.
          Check, too, to see if the thermostat has a mercury switch. If it does, make sure the thermostat hangs level on the wall. And check to see if the thermostat is in a cold draft, or if it's hanging on a poorly insulated, outside wall. Make the necessary corrections.

          The boiler is oversized.You're supposed to size the boiler and fire the burner to the connected piping-and-radiation load. In the boiler manufacturer's literature, they call this load the D.O.E. Heating Capacity. If your boiler is too big, its ability to produce steam will exceed the system's ability to condense steam. The burner will short-cycle.
          You may be able to solve the problem by down-firing the burner, but be careful when you try this. You may down-fire to a point where the flue gases begin to condense. Fire only to the connected load.

          The boiler is properly sized, but overfired.If there's too much fire, you'll get lots of steam in a hurry. That will quickly raise the boiler pressure and short-cycle the burner off the pressuretrol.
          Raising the pressuretrol setting isn't a good solution to this problem. Over-firing will also throw water up into the piping. This leads to water hammer, uneven heating and short-cycling.
          Check your gas pressure, or your nozzle size (on an oil-fired system).

          The boiler is making wet steam.Check the near-boiler piping against the manufacturer's specifications. If the piping can't separate the water from the steam, the water will cause the steam to condense, and the burner will short-cycle.
          Check the boiler water's pH and its cleanliness too. You may have to clean the boiler and the system and balance the pH with chemicals.

          The steam traps aren't working.Two-pipe steam is like a ladder. Each radiator is a rung on that "ladder," and at the end of each rung you'll find a steam trap. Part of the trap's job is to keep steam from entering the no-pressure side of the ladder. If even one trap fails in the open position, steam will jump across and pressurize the air on the other side of the system. As the pressure builds, the burner will short-cycle on the pressuretrol.
          Float & thermostatic and bucket traps serve the same purpose at the ends of the mains, and at the base of risers. If they fail in the open position, or, with bucket traps, if they lose their prime water, steam can move into dry return lines and cause burner short-cycling and water hammer.
          Trap maintenance is essential.

          The air vents aren't working.If they're not, the system will trap air and pressurize it. Remember, steam and air are both gases, but steam is lighter than air, so the two won't mix.
          When the steam heads down a pipe, it pushes air ahead of itself. If the air can't get out at the end of the pipe (through a vent), the steam will just compress it. The pressure builds, and the burner shuts off on the pressuretrol. The burner short-cycles, but that's not your only problem. The building also remains cold because the radiators and mains are filled with air instead of steam. Usually, someone comes along and raises the pressure. They mean well; they're trying to solve the short-cycling and give the folks some heat. But the higher steam pressure just compresses the air a bit more. It usually doesn't help the lack-of-heat problem. It just raises the fuel bill.
          Check the air vents, and clean or replace them where necessary.

          The pressuretrol or the pigtail is clogged.If there's sludge in the pressuretrol or the pigtail that connects the pressuretrol to the boiler, the burner will short-cycle. The pigtail's job is to fill with water and keep the steam temperature from reaching into the pressuretrol. A pigtail is a natural collector of sludge. If you can't clean the pigtail (a tough job), replace it.
          The pressuretrol has a mercury switch and it isn't level.Some pressuretrols have mercury switches. If the pressuretrol isn't plumb and level, the mercury might trip too soon. That can cause the burner to short-cycle.
          If the pressuretrol sits on a pigtail, make sure the curved part of the pigtail faces front to back (when you're looking straight at the pressuretrol). If you have the curved part turned from side to side (so you can see through the circle when you're looking straight at the pressuretrol), the burner might short-cycle. This is because the curved part of the pigtail straightens a bit when heated. As it straightens, the pigtail tips the mercury and stops the burner. When you turn the pigtail so that it faces front to back, it tips the pressuretrol from front to back, but not from side to side. This doesn't affect the mercury switch.
          sigpic

          Comment


          • #65
            Re: My boiler is short cycling

            Originally posted by DuckButter View Post
            yeah yeah yeah...the other way around.
            Who's on first?

            Also, referencing F & T trap on two pipe systems...I'm guessing you mean Hartford loop..(?)

            No, I mean a float & thermostatic trap. Here is a link to one

            http://www.boydeng.com/TrapSizing.htm

            Comment


            • #66
              Re: My boiler is short cycling

              [quote=NHMaster3015;131376][
              The thermostat is hardly ever an issue with cycling, its usually a pressure problem, i.e. the air cant escape from the vents fast enough and this will make the pressure rise faster then normal.

              www.heatinghelp.com

              This is right out of Dan Holohans book. Note the very first paragraph.



              EDIT* Note my use of the words "HARDLY EVER"


              Yes, I have been to many of Dan's seminars and have all of his books as well. I understand a t-stat out of calibration can cause cycling issues, but I can tell you that I service alot of residential steam systems and in all my years of doing it, I have yet to come across a t-stat whos anticipator was causing the boiler to short cycle.

              The O.P. said he fixed this problem by adjusting his cph to 1, I guarantee this is just a temporary fix.

              Comment


              • #67
                Re: My boiler is short cycling

                Originally posted by NHMaster3015 View Post
                Sorry, I'm a bit confused. Did this post say the problem was solved.?

                If not, the discussion of main vents. If you have a one pipe system there, you may not have main vents, the radiator vents serving that purpose.

                Radiator vents are not to be used as "main" vents. All 1 pipe steam systems should have some kind of main vent. Main vents are made to vent the mains and rad vents vent the riser, they are not made to be vents for the whole system.

                Comment


                • #68
                  Re: My boiler is short cycling

                  This has been a tough one because I'm not really sure what he has there. The pictures are good, but not conclusive enough. I have no doubt that he should replace most if not all of the radiator vents. People seem to think that they are a lifetime thing and you and I both know they ain't. Did he say he had F&T's in the house.? I can't remember, but if so these are very often the cause of a multitude of problems and most likely are in need or service. Is the system single pipe or two pipe.? Again I can't tell and I dont think he knows either. Two pipe, wet return systems are prone to blockage of the wet leg if it's below (and I've see above ones also) the boiler water level. When I approach these jobs I usually try to find out what changes have been recently made. Most of these old systems worked very well untill someone decided to mess with the piping and controls. And as you know, making a boiler change, soley based on btu\hr output can cause huge problems because the new low mass boiler make steam much much faster than the old pig they took out. Dropping the pressure can and often does take care of this problem, but you have got to make sure the radiators are all heating evenly. This can take some time. Anytime we do a steam change we replace all the vents because banging around on the old piping dislodges rust and crap and it all ends up in the vents.
                  I jumped on the thermostat because it was something that he had changed and these new didgital thermostats can cause problems with control systems if not properly calibrated.
                  sigpic

                  Comment


                  • #69
                    Re: My boiler is short cycling

                    I agree there is a gray area from the pictures and description. It is a one pipe system (he said he has air vents on the radiator).

                    Comment


                    • #70
                      Re: My boiler is short cycling

                      OK, just to make it more clear on my system. I will try to summarize what I have and the problem(s) in chronological order:

                      - It's a Weil-McLain EG-40 or 45 gas steam boiler

                      - 1 pipe system

                      - Honeywell CT3650 thermostat (not the T8600D as I originally thought, same family though)

                      - 2 wires to the thermostat, R & W. Heat only

                      - Bought the house in August. Turn on the heat around late Oct or early Nov.

                      - Don't remember if the boiler ever short cycle. Just know heat from the radiators was coming out more consistent

                      - Bathroom and master bedroom air vents would hiss loudly

                      - Master bedroom has a big water hammer noise a few minutes after the radiator gets heat

                      - Drained the boiler around mid Nov on a warm day. Drained until gauge glass water looked clean and clean water was coming out

                      - Took air vents out and clean them. Saw some improvement in the bathroom and master bedroom but water hammer still exist in master bedroom

                      - Changed CPH from default 6 to 3. This stopped the short-cycling somewhat. Eventually, I changed it to CPH 1 since that is the setting recommended in the Honeywell manual for a gravity steam system

                      - Pigtail is checked, not clogged

                      - Pressuretrol indicator is set between 2 and .5

                      - With thermostat or without thermostat by crossing the 2 wires, the boiler would turn on for approx. 20 minutes and stop once the it reach PSI 3. It will stop for approx. 1 minute for the PSI to reset back down to 0. Then fire back up for approx. 3 minutes before the it reaches 3 PSI again. This will repeat for a few more time before it reaches the set temperature in the thermostat

                      - Heat have always been even at all the radiators

                      - Replaced thermostat with a Honeywell VisionPro TH8110. Set CPH to 1. Yes, it is level

                      - Drained the boiler because I can see medium brown water at the gauge glass. Clean water at the guage glass and drain but once the boiler fires back on, I see brown water again.

                      - Replaced master bedroom air vent with the same brand and model. Also, the third bedroom air vent is replaced because it looks old and the vent was painted a bit. I replaced it with a bigger air vent. Now, I don't hear any or very minimum hissing from the bathroom, master bedroom, or the second bedroom. The third bedroom is hissing like crazy with the new air vent. Maybe I will try to put the old one back and see what happen.

                      - Water hammer still exist in the master bedroom after replacing the air vent in the master bedroom

                      - Don't see any air vent at the end of the main pipe

                      Originally posted by Masterplumb View Post
                      The O.P. said he fixed this problem by adjusting his cph to 1, I guarantee this is just a temporary fix.
                      So you think this is only temporary?

                      Comment


                      • #71
                        Re: My boiler is short cycling

                        Bathroom and master bedroom air vents would hiss loudly

                        This is due to the fact you need to add/replace main vent

                        - Master bedroom has a big water hammer noise a few minutes after the radiator gets heat

                        You need to check the pitch of the radiator, it needs to be piched towards the radiator valve.

                        - Took air vents out and clean them. Saw some improvement in the bathroom and master bedroom but water hammer still exist in master bedroom

                        You cant/shouldnt "clean" air vents. Replace them with the proper size orifice

                        - Changed CPH from default 6 to 3. This stopped the short-cycling somewhat. Eventually, I changed it to CPH 1 since that is the setting recommended in the Honeywell manual for a gravity steam system

                        1 cph imho is not enough. Replace the rad vents and install a new main air vent (sized correctly) and put the t-stat back to 3cph

                        - Pigtail is checked, not clogged

                        It didnt appear to me it was

                        - Pressuretrol indicator is set between 2 and .5

                        The pressuretrol should be set at .5 and the inside wheel should be set for 1 giving you a cut-out at 1.5 psi and it will come back on at 1.0

                        - With thermostat or without thermostat by crossing the 2 wires, the boiler would turn on for approx. 20 minutes and stop once the it reach PSI 3. It will stop for approx. 1 minute for the PSI to reset back down to 0. Then fire back up for approx. 3 minutes before the it reaches 3 PSI again. This will repeat for a few more time before it reaches the set temperature in the thermostat

                        3 psi is too high, set the pressuretrol like I stated above

                        - Heat have always been even at all the radiators

                        - Replaced thermostat with a Honeywell VisionPro TH8110. Set CPH to 1. Yes, it is level

                        It should be level but it really doesnt matter on a digital t-stat. Its just cosmetic.

                        - Drained the boiler because I can see medium brown water at the gauge glass. Clean water at the guage glass and drain but once the boiler fires back on, I see brown water again.

                        Steam systems can be very dirty. Try and stay on top of it by blowing down once a week.

                        - Replaced master bedroom air vent with the same brand and model. Also, the third bedroom air vent is replaced because it looks old and the vent was painted a bit. I replaced it with a bigger air vent. Now, I don't hear any or very minimum hissing from the bathroom, master bedroom, or the second bedroom. The third bedroom is hissing like crazy with the new air vent. Maybe I will try to put the old one back and see what happen.

                        Main vent!

                        - Water hammer still exist in the master bedroom after replacing the air vent in the master bedroom

                        Air vents and water hammer in the rad are different issues. See above about pitch.

                        - Don't see any air vent at the end of the main pipe

                        You need one at least.


                        So you think this is only temporary?
                        Yes I do. Replace vents, add at least one main vent and set tstat back to 3 cph

                        Comment


                        • #72
                          Re: My boiler is short cycling

                          Thanks Masterplumb.

                          The master bedroom radiator look pitched. Maybe I need to elevator it a little more.

                          I need to doublecheck but the last time I open the pressuretrol, I think the dial wheel was at 1.

                          As for adding a main vent, is there only 1 type?

                          Also, 3 cph is a better setting for a steam system?

                          btw, I noticed your location is NY. Do you cover Brooklyn?

                          Comment


                          • #73
                            Re: My boiler is short cycling

                            OK, I did 3 things tonight.

                            1) Very warm day today so I took this opp to flush the boiler again. I think I flush it more thoroughly this time.

                            2) I adjusted the pressuretrol to .5. Before it was between 1 and 2. I look inside the pressuretrol wheel, I see the 1 in front but not sure where the indicator mark is to know for sure it's set to 1. But I think it's set to 1 since the pressuretrol was set between 1 and 2 and the boiler would stop when it reaches 3 psi.

                            3) I checked the master bedroom radiator. It was pitched but I guess the wood that is being used sag somewhat to make the radiator even base on my level indicator. The radiator is about 32" and I elevated it approx .5". Too warm to test the boiler tonight. Will wait for a colder night.
                            Last edited by zuffy; 03-26-2008, 09:52 PM.

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                            • #74
                              Re: My boiler is short cycling

                              With thermostat or without thermostat by crossing the 2 wires, the boiler would turn on for approx. 20 minutes and stop once the it reach PSI 3. It will stop for approx. 1 minute for the PSI to reset back down to 0. Then fire back up for approx. 3 minutes before the it reaches 3 PSI again. This will repeat for a few more time before it reaches the set temperature in the thermostat.

                              Finally we've got somewhere. This here is a classic symptom of a boiler that is over fired. The fact that the radiators heat evenly (even though the M bedroom bangs a bit) means the radiators are indeed venting. (so is the main since if the main was'nt, neither would the radiators.) Changing the cph and or adjusting the pressure trol can slightly decrease the cycling but the main problem here is that the boiler is making steam at a rate faster than the systems ability to direct it. I would give your service Co a call and see if the change the firing rate for you.
                              sigpic

                              Comment


                              • #75
                                Re: My boiler is short cycling

                                Again we disagree but lets say it is over fired, and maybe I'm missing something but how do you properly and safely downfire a gas burner?

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