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Very slow depressurization time

Howdy,

Want to say right off, that this is the most useful forum I have come across on the net due to the helpful folks willing to give advice.



Now on to the issue I am seeing with my heat system...

I have a peerless oil-fired steam boiler that heats a 2-floor, 1800 sq ft, 1890 house that we moved into a few years ago. I have never had steam heat before so I'm a complete newbie in all things steam (I've ordered the The Lost Art of Steam Heating to hopefully fill in a bit of info). We've had our oil company provide tune-ups/inspections yearly with no major issues found.



After reading some info here and learning the proper pressure for this type of system to operate in, I observed our furnace and saw it reaching levels upwards of 15psi during heating (shows the value of those inspections!). Now knowing that this is an issue I spent some time investigating and determined the pigtail was nearly plugged shut. I replaced it and ordered a low pressure gauge to install on a T with the installed pressuretrol to get a better feel of what is going on.



I then did some testing with the pressuretrol...running the furnace and adjusting the cut-out to see if the psi numbers would match up. No matter what I did, the pressuretrol would not shut-off the system...thinking it's better to be safe than sorry in this area, I ordered a replacement. It should arrive tomorrow for me to install.



The last thing I wanted to check was the venting. I saw that when I ran the furnace, the pressure would be at 2psi in almost no time, with little to no heat reaching the radiators on the upper floor. I replaced the "rustic" looking main vents with a couple of vertical vent air valves and tested again...a bit better, but not ideal. So I took all the radiator and main vents off as an experiment thinking this would provide the slowest system pressure build-up and the fastest depressurizing. The pressure build up went at a very slow pace, would guess it would allow the house to heat evenly, but the depressurize took a surprising while. I also noticed that even after shutting the system down at ~2psi, the gauge would keep climbing to ~4psi or so.



After some tinkering with vents, my system seems to heat up ok...all radiators get some heat before the pressure cut-off kicks in, not as hot as I would like but much better than what was previously happening. However, it takes FOREVER (like hours) for the pressure to drop back down to a point that the furnace will kick back on. This severely limits the heat output of the system. Note that I'm manually monitoring the pressure during these tests, as I don't trust the pressuretrol.



What factors play in the system pressure sinking back to a safe level?





Thanks for any advice, guidance, etc.

Comments

  • conversiontime
    conversiontime Member Posts: 87
    new gauge in yet?

    If the gauge is not bad (and it sounds like it could be) there could be a block somewhere, perhaps crud has clogged the wet return. Or your boiler piping may be incorrect. If you have main vents and rad vents removed, then steam should never build much pressure as it will be rushing out the vents. Little puzzled by that part of the description. As others will tell you pics of your near boiler piping may be in order.
  • BobC
    BobC Member Posts: 5,471
    Do you trust the gauge?

    Did you check to be sure the little hole at the base of the pressuretrol (inside the brass fitting) is clear? If there is crud in there the pressuretrol won't "see" the boiler. Your pressure gauge could be flaky, they don't last forever.



    Does the water in the gauge glass move around a lot? If it's going up and down a lot the boiler might need to be skimmed. What kind of main vents did you install? And what kind of vents are on your radiators?



    Post some pictures of the boiler and the piping around it.



    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
  • Chris15
    Chris15 Member Posts: 8
    no new gauge in hand

    Unfortunately, I had to order the gauge online, as nobody around here carries low pressure gauges apparently. I really don't trust that gauge. it goes a bit below zero at rest...is that normal? Though even if the gauge is bad, the pressuretrol never ever shut off the boiler in all the time I've lived here and I've heard vents hissing. Maybe I have a few unrelated issues :)



    I am tempted to pick a temp 0-50psi at lowes tomorrow just to throw on near the pressuretrol to get a rough idea of what's going on.
  • Chris15
    Chris15 Member Posts: 8
    Nope no trust here

    Did you check to be sure the little hole at the base of the pressuretrol (inside the brass fitting) is clear? If there is crud in there the pressuretrol won't "see" the boiler. Your pressure gauge could be flaky, they don't last forever.



    I did check the little hole, looked pretty clean as far as I could tell.



    Does the water in the gauge glass move around a lot? If it's going up and down a lot the boiler might need to be skimmed.



    When the boiler gets really going the water is bouncing up and down quite a bit. Is skimming a job that could be tackled by a non-pro?



    What kind of main vents did you install? And what kind of vents are on your radiators?

    the only thing that Home depot had at the time, some 3/4" straight "Steam Radiator ventAir Valve". My radiators have Maid O'mists of varying sizes depending on their placement.



    Post some pictures of the boiler and the piping around it.
  • BobC
    BobC Member Posts: 5,471
    Vacuum is normal

    Perhaps the boiler and system are well enough matched that you never build any real pressure unless it's very cold; it will be interesting to see what the new gauge shows. Make sure there is a pigtail between the new gauge and the boiler.



    It's normal for a small vacuum to form when a boiler shuts down.



    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
  • Chris15
    Chris15 Member Posts: 8
    Couple O'questions

    I pulled the existing gauge off and it and the pipe that comes out of the boiler to the T has a bunch of sludge in it.



    A few questions if you don't mind:

    1. How should I clean that pipe without pushing the junk into the furnace? Any cleaning agents or tools to use?



    2. Should I replace the T that the pigtail and gauge meet at and if so, can I use just teflon tape and megalok to re-seal?



    3. Should I plug where the gauge currently is and move it (the new one I'm getting anyway) up off the T with the pressuretrol?



    Thanks!
  • Chris15
    Chris15 Member Posts: 8
    Skimming

    One more thing...I've read up a bit on skimming and undertand the procedure, but I'm not sure what on my boiler I should be using as the output pipe.  Any suggestions?

    Thanks.
  • BobC
    BobC Member Posts: 5,471
    Place to skim

    Can you remove the pipe (3/4"?) that the gauge is on and clean it away from the boiler? Also adding a nipple at the output of that T might not be a bad place for a skim port. You could mount the gauge on it's adapter for normal use and just unscrew the gauge and adapter to use the open pipe as a skim port. Get the pipe reducer in brass and use teflon tape to seal it so you can get it off easily when you want to skim. I hang a 2 gallon bucket from the floor joists on a chain to skim into because i just don't have room for a 5 gallon pail (burner directly below the skim port) but then I'm lazy.



    By code you do need a 0-30 gauge but I would add a 0-3 PSI gauge on a T off the output of the pigtail.



    One of the guys on the board just posted a procedure to build a "wand" to clean the inside of new boiler with but with an old boiler you might want to use some washing soda in the boiler to clean it out. If you search the wall you should be able to find that thread. Just don't allow the boiler to some up to steam with the soda in it and flush it out good when your done REMEMBERING to let the boiler cool so you don't stress the cast iron by dumping a torrent of ice cold water into a hot boiler.



    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
  • Chris15
    Chris15 Member Posts: 8
    Gauge placement

    Does the placement of the existing gauge under the pigtail, directly connected to that straight pipe make it more likely to get ruined with sludge than if it were up above the pigtail?

    I saw a diagram on this forum with both the 0-3 and 0-30 gauges above the pigtail, on a T with the pressuretrol and I am thinking about implementing it that way if it would extend the life of the gauges.

    Thanks for your help Bob.  I'm learning a lot here.
  • Chris15
    Chris15 Member Posts: 8
    Just one more...I promise

    I wasn't able to get the 3/4 T off without taking the entire pipe that comes out of the boiler off. It is pretty corroded inside so I think I should replace it while it is off. It looks like black iron, is this correct? Is there any special sealing process I need to follow to re-install it other than teflon tape and Megalok?
  • BobC
    BobC Member Posts: 5,471
    edited November 2012
    Clean the boiler

    Good to see that came off with some ease, You could mount the pressuretrol and both gauges off the pigtail out of that reducer (after it's all nice and clean), now you just need a nipple and a cap to close off what's going to be your new skim port. Everything should be in black steel or brass. I think you have a lot of crud in that boiler, do you know if it was ever skimmed?



    i would drain and flush that boiler as best you can to get rid of some of the crud in there; put a hose nozzle into that open tapping and then see if you can blast away some of the crud (make sure you kill the power first). It's going to be a bit messy so just make sure you can capture the water coming out of the drain and try to not get any on the burner. When your done put a cap on the new skim port, fill it with water and fire up the boiler to drive off the oxygen in the water; after its run for a couple of days you can start to skim some of the crud you have dislodged. Make sure you skim nice and slow, no more than 5 gallons in two hours.



     I just replaced a 16 year old boiler because of a failing oil tank (and cheap natural gas) and the pigtail, gauge and vaporstat were clean as a whistle after all that time. If you get that boiler water clean you shouldn't have anymore problems with clogged pigtails. This picture shows the setup on my old v75, you would just have to add the 0-30 gauge besides the 0-3 shown here.



    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
  • Chris15
    Chris15 Member Posts: 8
    Changes

    Ok...mission successful?



    As the pictures show, I replaced the 3/4" black pipe and brass T. Added a plug and a T to separate the pressuretrol and pressure gauge. The only gauge I could find in the short term is a 0-100psi, but I have a 0-3 and 0-30 coming soon that I'll put on the horizontal piping with the pressuretrol.



    I skimmed for a couple of hours and the water seemed a bit filmy. I don't have time to keep working it tonight. I'll get back to it this weekend.



    The boiler is running right now, once it builds up a bit of pressure I'm going to go play with the pressuretrol to make sure it shuts down at roughly the right pressure.



    Anything to be worried about? :)



    Thanks again for the advice Bob.
  • BobC
    BobC Member Posts: 5,471
    Should work

    That should work fine.



    I've skimmed my boiler 5 times in the last month and I think I'm just about there. It takes time and I prefer to do iyt a few hours at a time while I'm working at the bench. Just don't forget to bring it up to steam when your done to drive off all the oxygen.



    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
This discussion has been closed.