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Short Cycling

Hi



I have a 2 pipe steam system in a 1200sqft single story home. I am noticing that the boiler will run until it reaches a pressure of 4psi. At this point the pressuretrol (which is set all the way to minimum) will shut it down for about a minute until the psi falls to about  2psi. The boiler will restart and this on/off cycle will continue until the home warms up. I have noticed that the boiler pressure does not rise the first few minutes until the main vent (a bullet style but with no name) on the condensate side gets hot. (This is also the only vent ever to be installed in the system by what I can find.) By what I understand, the vent needs to close to lock steam in, but then how do I keep the boiler from building pressure and shutting down?



Thanks

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 18,923
    edited February 2014
    Ah... that's not how steam works

    That pressure, to begin with, is much too high.  a steam system -- even a block simple two pipe system -- never needs a pressure over 2 psi, and shouldn't start to build pressure until all the radiators are hot.  Some steam systems which are really well balanced never build any pressure to speak of at all!



    Now...



    First, it should be possible to set that pressuretrol to no more than 2 psi cutoff, and 1 psi cutin.  If not, it needs to be replaced with one which can be.



    Second, you say that it takes "a few minutes" for the vent "on the condensate side" to get hot.  That vent -- and the whole condensate side -- should never get hot (and that vent should stay open).  Each radiator should have, on the outlet, a trap (unless this is one of a variety of vapour systems -- in which the steam pressure should never go over a few ounces, never mind pounds).  These traps serve to let air and condensate out, but not steam.  The outlet pipe may  get hot, sometimes quite hot -- but not steam hot.  It is quite possible that one or more of these traps has failed, and is allowing steam to get by, putting pressure on the outlet -- condensate -- side.  When that happens, the system will heat very poorly and unevenly, if it heats at all.  So you should go around the house and feel the outlets of each radiator when the system is running.



    You will need a lot more main venting, but before we can go much farther we need a more complete description of the system, and particularly a description (better yet a picture) of the a typical radiator with its inlet and outlet devices.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • KnightRider
    KnightRider Member Posts: 20
    Steam passing right through radiators

    I have checked the piping in the basement with a temp gun and have found that some of the condensate pipes exiting radiators are only about 90 degrees while others are 200+ degrees. The pipe just beneath the vent on the condensate line just before it returns to the boiler also reaches 200+ degrees. Here are several pics also...



    PS- I plan to insulate those pipes in the near future as well
  • Jamie Hall
    Jamie Hall Member Posts: 18,923
    Dollars to doughnuts...

    those radiators with hot condensate lines have failed traps.  It happens.  Next thing to do is identify the make of trap and obtain replacement parts.  A good closeup of the trap and we should be able to help...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EzzyT
    EzzyT Member Posts: 1,201
    Near boiler piping

    That near boiler piping looks horrendous and needs to be corrected to also help with the issues you are having. Try to find manual on the boiler and take a look at the piping schematic and you'll see what you have is completely wrong
  • KnightRider
    KnightRider Member Posts: 20
    Is this the top of a trap?

    I am looking on the exit side of the radiator. Just want to make sure I am looking in the right spot before I go through the effort of removing a front panel, as I am sure they are all stuck fast with paint...
  • KnightRider
    KnightRider Member Posts: 20
    @EzzyT

    Are you referring to the painted piping or the newer looking copper and black pipe. That boiler was installed less than one year ago as a replacement for an old oil burner. Either way I will dig out the paperwork that was given to me after install and perhaps the outfit that put it in will be getting a call from me...



    Thanks
  • EzzyT
    EzzyT Member Posts: 1,201
    Trap

    That's not the top of the trap the trap is located on the outlet side of the radiator/ convector. From the previous pictures you've posted the ones with the piping on the bottom of the convector that's where the traps will be located
  • EzzyT
    EzzyT Member Posts: 1,201
    Old and new piping

    Copper piping doesn't belong on a steam steam system especially on the near boiler piping. The old painted piping is piped into a bullhead tee which has to go so both steam mains need to piped coming off the header separately. The new boiler piping is also really bad. The header and equalizer no where near what it's supposed to be. What make and model is your boiler and the btu rating?
  • EzzyT
    EzzyT Member Posts: 1,201
    Sizing the boiler

    Another key thing you need to check is to make the boiler was size properly to the equivalent direct radiation of the system
  • Steamhead
    Steamhead Member Posts: 15,331
    No

    on convectors like this, the trap is either installed at the convector's return connection, or it's installed in the basement under the floor. I'd bet on the latter since I didn't see one in your convector pics. See if you can locate a trap or two, and post pics of them.



    If there are no traps, you have an Orifice system. Let us know.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • EzzyT
    EzzyT Member Posts: 1,201
    Orifice system

    Frank from what I've seen in the field and have looked up in literature that I can find I've never seen a orifice system using convectors or originally designed using connectors only seen them with cast iron radiators. I'm sure you have since your been doing this a lot longer then I have.
  • KnightRider
    KnightRider Member Posts: 20
    Must have an Orifice system...

    I cannot find anything but piping even under the floor. Here is a pic under a small radiator.



    Thanks for all your help so far guys. Its appreciated.
  • EzzyT
    EzzyT Member Posts: 1,201
    unions

    the orifice must be located in the unions on the return side of the convectors. you can check by taking apart the union
  • EzzyT
    EzzyT Member Posts: 1,201
    install

    the company that installed the boiler wont come back and make those corrections on there dime and most of all they clearly dont know anything about steam systems so its best you find a company that really knows what there doing
  • KnightRider
    KnightRider Member Posts: 20
    @EzzyT

    The boiler is a New Yorker model CGS50A. Heating capacity of 115MBH.

    Here is also the pipe diagram in the installation manual. It looks to me like the Hartford loop is not the same, perhaps even nonexistent on my system.
  • EzzyT
    EzzyT Member Posts: 1,201
    edited February 2014
    Piping diagram

    It's very obvious to see the huge difference on how your boiler is piped versus the way it's supposed to be piped according to the boiler manual. Ideally the best way to pipe a Hartford loop is using a wye but most plumbing and heating distributors don't have them in stock. Using a tee close nipple and a elbow works great too.

    Do you know if your boiler was sized properly? I doubt the company who installed it did a proper EDR sizing.
  • KnightRider
    KnightRider Member Posts: 20
    Dont know for sure if it is the correct size.

    The company that installed the boiler went around and measured the radiators and did some calculations, but beyond that I dont know for sure.
  • EzzyT
    EzzyT Member Posts: 1,201
    EDR

    Measuring the convectors and determining the square feet steam of each one and then adding them all together will give you the EDR rating the system is which in them is how you size the boiler . Where are you located ?
  • Double D
    Double D Member Posts: 414
    edited February 2014
  • KnightRider
    KnightRider Member Posts: 20
    Location

    I am in York, Pennsylvania
  • KnightRider
    KnightRider Member Posts: 20
    EDR

    Using EzzyTs method I am getting 111 square feet of steam. When using the link provided by Double D, I am getting 226.3 which is just a bit different. Perhaps I am wrong using Cabinet Convector Copper Element. I believe that is what I have...



    Dims of convectors in inches:

    31x6

    27x6

    16x6

    20x6

    60x6

    32x6

    36x6

    Cabinets are 24" high

  • Double D
    Double D Member Posts: 414
    Just an example

    If your total EDR is 226.3, An example of a properly sized boiler would be a Peerless 63-03L rated at 233 sq.ft EDR which would make your existing boiler oversized for the application.

    http://www.peerlessboilers.com/Products/ResidentialBoilers/Series63/tabid/114/Default.aspx#dnn_relateddocuments

    Related Documents: Catalog literature series 63&64
  • KnightRider
    KnightRider Member Posts: 20
    OK, Think I see

    Checking my boiler manufacturers website states that my model is rated at an AHRI Net Steam (sq. ft.) of 358. If I only need 226 then the boiler I have is producing more steam than what the system needs. I would assume that this is helping to cause the issues that I am having?
  • Double D
    Double D Member Posts: 414
    Part of the problem

    but you still need to correct your near boiler piping. If both of those pipes leading to the vent are return lines from the ends of the mains and return sides of the radiation, each one of them need to drop independently below the water line of the boiler along with separate vents for each. You should not group dry returns above the water line of the boiler. Where does the pipe close to the floor directly behind the water heater lead to? Also could you show where the grouped returns at the vent lead to?
  • EzzyT
    EzzyT Member Posts: 1,201
    Yes

    And with the boiler being piped wrong you'll continue to have issues
  • Fred
    Fred Member Posts: 8,518
    What about piping?

    If the radiators have an EDR of 226, shouldn't he add another 30% to 33% for the piping? That would make his boiler requirement around 294 to 301EDR. His current boiler is still a little larger than needed but not that bad, if my assumption about the piping is correct.
  • SWEI
    SWEI Member Posts: 7,356
    EDR ratings of boilers

    include this already.  Just match square feet to square feet (most of the time.)
  • BobC
    BobC Member Posts: 5,306
    EDR should equal sq ft of steam

    The boilers sq ft of steam should equal the EDR of the radiators if possible because that includes a 30% allowance for piping. If you add another allowance for piping you will be oversized.



    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • KnightRider
    KnightRider Member Posts: 20
    pipe runs

    Sorry for the delay getting back to this. The pipe close to the floor goes over and into a crawl space at that end of the house(pic 1). It will continue to travel around and go to the other end of the house(pic 2). The returns from the vent also go in opposite directions. Into crawl space(pic 3). Then to the other end of the house(pic 4). I hope this is clear, if not perhaps I could take a video and attach it to this post to help out.
  • Double D
    Double D Member Posts: 414
    Question

    Are the pipes close to the floor joist in picture 2 tied together? It looks like they are but I need to know for sure. If so, are the pipes in the crawl space also tied together in a similar way? I'm talking about the ones that lead to the main vent at the boiler.
  • moneypitfeeder
    moneypitfeeder Member Posts: 248
    edited February 2014
    Here's a well respected pro

    Hi,

    I work close to where you live, and if you need I could probably help you id components of your system, but here's the name of a guy that's well known and respected pro around here that I'm pretty sure counts York as in his area: http://www.heatinghelp.com/professional/79/All-Steamed-Up-Inc
    steam newbie
  • KnightRider
    KnightRider Member Posts: 20
    Pipes are tied together

    The pipes in previous picture #2 are tied together at the end of the runs with a T as shown in new picture #1. This condensate line is the one that then passes directly under the main vent. This setup is the same in the crawl space except for the fact that 3 convectors are connected together in there (pics 2,3,4). The lines to and from the crawl space are the ones that go off to the left in the previous picture of the boiler itself.
  • KnightRider
    KnightRider Member Posts: 20
    edited March 2014
    Pipes are tied together

    having technical difficulties... Pics 2,3,4
  • Steamhead
    Steamhead Member Posts: 15,331
    I have

    almost all of them were Trane, in which the orifices were cast into the convector elements. There's a neighborhood just north of Baltimore that's full of them. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Double D
    Double D Member Posts: 414
    Back to square one

    I was able to see the main at the end drop to the wet return. With the new pics you put up I see it's the same in the crawl space. I needed a better view of the end of mains where the end appeared to be tied to the dry return leading to the vent. Since they are not and there appears to be no traps on the convectors or in the basement, someone will have to identify where this systems orifices are. I'm eager to see what Frank from All Steamed Up, Inc. has to say if he chimes in again.