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EZ-Gas and Smith G8 rumble - fog horning?

BobC
BobC Member Posts: 5,502
edited November 2014 in Gas Heating
I had a Smith G8-3 installed two years ago with the EZ-Gas burner. I have had a low frequency rumble since it was installed that is obviously combustion noise. The system works well - 84.5% when it was checked last month.

There is another thread about a Lochinivar fog horning and some mentioned it might be because the meter and the burner regulator being too close. Could this be the problem I have with the roaring I am experiencing?

The output of my 230 MCF meter comes across the cellar with a 10 ft 1" pipe, at that point is splits to two 3/4" feeds - a 7 foot 3/4" vertical feed into the boiler regulator and a 3 foot horizontal run to a 7 ft vertical feed to the 40 gallon gas hot water regulator. The horizontal feed to the water goes on to feed a gas range through about 20 ft of 3/4" pipe.

I know the output of the boiler gas regulator is bouncing around, I have not checked it's input top see if it's bouncing.

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

Comments

  • Steamhead
    Steamhead Member Posts: 17,380
    What are the combustion test readings?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • BobC
    BobC Member Posts: 5,502
    The readings are -

    o2 5.6%
    ⁃ co2 6.6%
    ⁃ flue 260
    ⁃ co 21ppm
    ⁃ eff 84.5%

    The chimney is in the middle of the house and about 30 ft tall.

    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
  • icesailor
    icesailor Member Posts: 7,265
    What's the draft at the breeching and in the chimney?
  • BobC
    BobC Member Posts: 5,502
    His printout does not show draft. The previous readings showed -0.04 at the boiler outlet

    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
  • icesailor
    icesailor Member Posts: 7,265
    edited November 2014
    Running? Or, running, then not running?

    Didn't a Smith G8-3 start out as a oil boiler? Its converted to gas? Does it have a Model M double acting draft control on it? How much draft is there when the damper is held closed? Does it swing with the weights in the lowest position?

    As a oil person, I consider that .04 negative draft as a tad on the low side. Oil burners "blow their fog horn" when they have low draft and they get dirty. How old is the chimney? Does it have tiles in it? Is it a multiple flue chimney?

    Most of the chimney masons I know are clueless about draft and what can upset it. I've seen brand new two flue chimneys with more draft in the fireplace ash dump than in the boiler flue.

    Is the flue properly sized?
  • BobC
    BobC Member Posts: 5,502
    The boiler runs fine, it's just loud. The boiler was installed with the gas gun a couple of years ago, the chimney has a 8" flue with a 6" liner and cap that was installed when the boiler was. It has the double acting draft control and a spill switch. It swings whenever there is a breeze and there is always a breeze on the coast.

    i don't know what the draft is with the draft control closed.

    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
  • Tim McElwain
    Tim McElwain Member Posts: 4,642
    First of all the readings you gave do not line up an O2 of 5.6% will not line up with CO2 of 6.6% the flue temp of 260 is way too low and the efficiency number is totally incorrect. It looks like you have an air adjustment problem and are getting too much excess air. The combustion analyzer that was used may need some servicing as it is not matching O2 and CO2 correctly. Was this installation done by a professional?
  • RobG
    RobG Member Posts: 1,850
    Just because someone has an analyzer does not mean they know how to use it.
  • BobC
    BobC Member Posts: 5,502
    The boiler and gun were installed two years ago by a local company who set it up with a combustion analyzer, I commented that it was making too much noise so they detuned it slightly to soften the roar.

    I had a different company give the setup a going over to make sure it was all set for the heating season about a month ago. They said it was clean as a whistle and they did a combustion test.

    I have no idea if either analyzer was calibrated or used correctly. I do know the gun is firing at 90,000 BTU (I clocked the meter) and the air band is set a little below 20%.

    I'll put a thermocouple into the boiler output to see what I get for a reading, not much I can do about o2 and co2 but I can check the temperature.

    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
  • Tim McElwain
    Tim McElwain Member Posts: 4,642
    The G-8 * 3 is what you must have. Do you know what size orifice it has it should be 9/32 set at 3.5" W.C. outlet gas pressure. I am not sure of that air band setting as I do not have my Carlin EZ manual handy.

    You stated that the outlet of the boiler regulator was bouncing around . . . How do you know that did you take a gas pressure reading? If so what was it doing.

    The specifications from HB Smith on the G8 with a Carlin EZ gas burner state that they want an overfire draft of -0.02. The boiler should be firing at 105,000 BTU's also according to Smith Specs

    Smith actually sells that boiler now with an EZ burner in it from the factory.

    I would contact them and see what they suggest on the noise issue. www.smithboiler.com or 413-562-9631.

    I have a feeling the boiler is not set up correctly or someone who is servicing it does not know what they are doing.
    icesailorRobGZman
  • BobC
    BobC Member Posts: 5,502
    The orifice is drilled to 0.203". The burner came from the factory set up for the Smith G8-3 but was replaced with a slightly smaller orifice because my connected load is smaller than the boiler is rated for. I saw his manometer bouncing from 3.2 to 3.7" very quickly, when asked he said they sometimes do that.

    When he was setting the air band the roaring changed a little but never dramatically reduced.

    My stove shows no signs of flame instability but it might be too fast to see. I read that valves sometimes chatter if they are too close (less than 15 pipe diameters?) to each other, but mine don't seem that close. The roaring is loud enough that I can't tell if the gas valve is fluttering - I'll see if I can borrow a stethoscope to verify that.

    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
  • Tim McElwain
    Tim McElwain Member Posts: 4,642
    The bouncing pressure between 3.2 to 3.7 is not correct and indicates a problem with the gas valve servo regulator. It is not properly sensing down stream demand and is surging looking for a stabile demand. Both your air and gas mixture have to be correct with this burner or it will make noise. You need to find someone who knows what they are doing to solve the noise issue. If not then contact HB Smith or Carlin for help.
  • BobC
    BobC Member Posts: 5,502
    Good luck trying to find someone that knows what he is doing these days, if you want something done your best doing it yourself. I checked the stack temperature with a known good thermocouple and it was 410 F so something was off with that techs meter.

    I put a manometer on the gas supply for the boiler and found it was dropping from 8" to a little over 5" when the boiler fired and the output of the gas valve showed the pressure bouncing around 3.5", the gas supply was modulating and that was the source of some of the rumbling I was getting.

    I called the gas company and they came out and confirmed the pressure problem. They reamed out the pipe that went out to the street and that improved things a little bit. They said they would be back in a day or two to replace the pipe. Yesterday they installed a new 1-1/4" plastic pipe from the street into the house and 1-1/4" steel pipe up to a new gas meter. Tyhe connection from the old incoming 1-1/2" pipe reduced to 3/4" and went up to the old meter.

    I used the manometer again and found the pressure at the boiler gas valve was 9.3" and went down to 9" when the boiler fired. The output of the valve was 3.5" and reasonably steady, digital manometers seem to need a bit more hysteresis - to sensitive.

    The rumbling noise is about 80% less now so I'd say the noise issue is fixed.

    The combustion numbers are o2=3.4%, co2=9.9%, co=16ppm and eff=83%. This was with a Bachrach Fyrite Pro meter.

    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
  • Tim McElwain
    Tim McElwain Member Posts: 4,642
    That looks good I think you are all set have a nice warm winter with low gas bills.
  • BobC
    BobC Member Posts: 5,502
    Thanks for confirming my problem Tim!

    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
  • icesailor
    icesailor Member Posts: 7,265
    Someone I worked with or for had an expression. I used it too. It works well.

    "When I need help, I call me".

    Watch that show on TV on Discovery Health, "Mystery Diagnosis". With every case, there is a diagnosis of "Its all in your head". Until someone goes a step further and figures out what is REALLY wrong.

    If you call someone and they have to come twice and still not solve the problem because they can't check the pressures, he still wants to be paid for doing nothing. But the digital pressure equipment so you can tell the gas company what is going on.

    If you do oil and don't have gauges, you aren't qualified to do oil. I say the same about gas.

    Just because they say they know what they are doing, or you think they know what they are doing, doesn't mean that they do know what they are doing.

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