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Pressuretrol question, yet again

Hello all.  I've been reading several threads on this fabulous bulletin board, and have become a steam heat info addict.  Our system is a single pipe steam with a gas fired burner. We live in our house 44 years and just completed our second boiler conversion.  The resulting spurting air vents, pressure producing steam jets, and intermittent success getting the radiator at the top of the far end riser hot, have sent me furiously searching for answers.  Thank you all, you've provided them. 



 I have the pressuretrol Main set to 1 lb, and the subtractive differential = 1/2.  Not sure how much lower I can go.  The main scale is not exactly marked in reasonable increments.  Lowering the pressure, still didn't completely stop the spitting and hissing. With the Main scale at 1 lb, what should the differential be?  At 1/2, I think any other adjustments must be made to the Main scale or cut-out. Can someone please clarify this? Thanks.

Comments

  • Boiler Talk
    Boiler Talk Member Posts: 134
    spurting air vents, pressure producing steam jets,

    I had new boiler put in in September and one of the main vents got stuck open.   I was losing water every day.   I suppose if your vent is making a steam jet, could be something clogging the vent.  Please be a bit more specific about your problems.  Where are the vents making the jets?  Is your water glass tube clean?  Did you have any service since installation?  Do you have banging radiators? 



    Pressuretrol relates to how much pressure ( PSI)  the boiler will allow before it cuts out for safety reasons.  Did you notice how high the PSI went? 
  • Steamhead
    Steamhead Member Posts: 14,319
    Also post some pics

    of the installation- I'll bet there's something else making those vents squirt.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
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    Baltimore, MD (USA) and consulting anywhere.
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  • TanyaK
    TanyaK Member Posts: 5
    Several problems, serious learning experience

    Here's some background. The first problem was located in our addition that has 2 radiators. Bubbling and squirting resulted in the change to varivalve in one of the radiators. Then the other one developed water hammer, so plumber put a new varivalve on that one, too.  But this was not the solution.  After the steaming baseboard in an adjacent room and water flooding out of the new varivalve, our plumber came and reduced the pressure.  He lowered the Main scale, but not the differential. That helped, but that's when I began looking for more answers.  Dan Holohan's articles helped me to align the differential, but most of the info is on additive differential, so that's why I asked about my configuration.  I've been tweaking this over the last few weeks, and under the less is better theory, lowering it, and testing it, but this is where i've stopped because the subtractive differential has me confused. The pressure is at 1 lb cut-out and 1/2 cut-in, and I really want to know if I'm understanding this correctly. Currently Main =1 differential=.5, but if the differential is .8 is the cut-in .2?

    Also, don't want folks to become too distracted by the various problems here, yesterday we had the main vent replaced, and while it's too soon to know for sure, the system seems to be more stable, no spitting, and quiet.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,288
    Varivalves

    Varivalves usually work well, but they're floatless, so they won't close on water. Ordinarily you shouldn't be getting excessive water in your radiators, but until you get that sorted out, you might want to go with a float-equipped vent.



    Similarly, some popular main vents, like the Hoffman #4 "quick-vent" and the Dole knock-off, are also floatless and should be mounted on a 6-10" nipple.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • TanyaK
    TanyaK Member Posts: 5
    Funny you should mention Hoffman #4

    Good idea! Definitely should have Known to try the Hoffman 1A, since we have hoffman valves on most of the radiators. Also, we just replaced the #4, which was our only main vent, with a Hoffman 75. Do the Gorton & Hoffman vents need minimum 6" nipple? Or can they be a bit lower? We're close to the ceiling, already.

    I did read Gerry Gill and Steve Pajek's paper on Balancing Steam Systems using a Venting Capacity Chart, but wasn't able to identify our vent until 2 days ago. Since our system was using the #4 as a main, which has much less capacity than the 75, we should be doing better. Also I do know first hand, that the #4 doesn't stop water, as I did overfill the boiler several years ago, and that's one of the places the water escaped.
  • neilc
    neilc Member Posts: 1,202
    New problem ?

    If this is a new problem, with this new boiler, then you should probably post pictures of the boiler and the connected piping above and around around the boiler.
  • neilc
    neilc Member Posts: 1,202
    edited March 2012
    New problem ?

    ooopps, double post
  • Mike_D
    Mike_D Member Posts: 33
    edited March 2012
    Baseboard radiators?

    You said that your baseboard radiators are squirting with one pipe. Have you checked to make sure that they are properly pitched? Dan's book discusses it on pg. 98 (TLAOSH). Some folks think that baseboards don't really belong in one pipe systems.



    Mike
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,288
    Extensions for main vents

    The extensions are basically there to prevent water from leaking out the vent if it reaches that level. Ordinarily the water should never get that high anyway, of course, but if it does, the extension keeps it from leaking until it gets to the top of the extension, so a 6" extension lets it rise another 6" before leaking, a 10" extension gives you 4 more inches. If your main vents have floats, the float will keep the water from leaking, assuming the float and valve are working.



    Most vents, other than the varivalves and the Hoffman/Dole #4 have floats, and you can tell if a vent has a float by turning it upside down or shaking it--you can hear the float flopping around inside. Also, the vents without floats tend to be a lot smaller in size. Compare your Hoffman #4 and your varivents to a typical radiator or main vent and I think you'll see what I mean, but the only way to know for sure is to read the product details from the manufacturer.



    As far as I know all the Gorton vents have floats. In fact, I believe their floats are made of either copper or brass, so they're more likely to keep working than some of the cheaper vents with plastic floats.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • TanyaK
    TanyaK Member Posts: 5
    Baseboard no longer steaming

    We were able to resolve the baseboard steaming & squirting by lowering the pressure to 1 lb. I also am understanding why there's water squirting with the new system. Without changing the air vent on the offending radiator, I've figured out the reason there is more condensation with the new system. Our old boiler supplied hot water to our home. Now we have a separate hot water heater, and the boiler produces steam heat only. Consequently if the system hasn't run all day and the temperature stays higher than the thermostat setback setting, when the program turns up the heat, it takes time to make this steam, and every time the heat has to generate like this, we get squirting. I modified the program setback, and haven't had the problem. But, who knows, until the high pressure destroyed the old vent, which was definitely a float type, and our plumber replaced it with the varivalve, we never had the problem. Thanks to Hap_Hazzard for point out the difference in this type of vent. Tomorrow, though I'm switching it for a Hoffman 1A. We'll see what happens.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,288
    But under normal circumstances

    Radiator vents should close on pressure. You shouldn't need them to close on water unless you're getting an unusual amount of water there. Your observation that it happens after recovering from a setback indicates that condensation is part of the problem, so Mike D's suggestion to check the pitch is right on the money. Also check the size of the supply and make sure the valve is not partially closed.



    It's not unusual to see baseboards piped with 3/4" or 1" copper when the EDR of the baseboard would require at least 1 1/4", so when it's really churning out a lot of heat, the water can't get out past the inrushing steam, and you get a baseboard that gradually fills up with water.



    The way I keep my oversized fin-tube baseboard (piped with 1" copper) from getting water-logged is by using a small vent, so it fills gradually. It still puts out adequate heat, due to its size, so if that's the case with yours, you might try closing down the varivalve first before you replace it and see if you can find a point where it gives you enough heat without filling up with water.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • TanyaK
    TanyaK Member Posts: 5
    The baseboard is not a problem, it's the upright with the varivalve.

    We resolved the baseboard issue. Now working on an upright 60 EDR radiator. I set the varivalve to the lowest possible setting and still got water. This consistently happens when the boiler runs from a cold start. On colder mornings, the setback temp is met during the night and the boiler runs before the wake up program kicks in. Once recovery mode begins at 7:30 everything heats by 8am and there's no water.



    You may be on to something with the radiator pitch. I checked and it's level. I'm thinking this was always a problem, but never realized it since the old vents were float types.



    Compared the venting capacities of the varivalve to the Hofffman 1A, and found I can slow the Hoffman more at low settings, so I switched it. I'll be able to hear the condensation even if the float holds it back, now that I've identified the sound. So we'll see. Temps will be warm in the next few days, so that can be good for testing, since the thermostat may not reach the setback temp. Will let you know what I learn.



    Thanks for the excellent feedback.
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