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Prestige Excellence puffing porpane

oak
oak Member Posts: 22
My first post on this question did not get any replies. Any advice on whether the periodic internal gas release (propane smell around boiler) would be caused by a bad solenoid or should we look elsewhere? What would you change first?

August 11 in THE MAIN WALL:

Smell of propane drops out the bottom of the boiler cover box; happens periodically (evey hour or so) with no apparent relationship to firing and use cycles.
The leak does not show itself using a spray-on leak detector.
Gas leak detector reacted but test inconclusive.
We could not replicate the gas release; seems to be out of the gas valve area (ie, not a leak so much as a release in the ignition area)
Seems to happen when the boiler is not firing (after the tech went home, of course)
The propane smell even happens after boiler is turned off and the supply of gas is shut off (for 2 days after shutting off gas).
We changed the igniter and temp sensor.




Comments

  • JUGHNE
    JUGHNE Member Posts: 11,042
    edited August 2015
    I would start the boiler and while it is firing shut off the gas valve on the supply pipe. (should be outside of the boiler).

    This burns all the gas out of the piping between supply valve on the gas pipe and burner gas valve. (Removes pressure in that part of the line.) Shut off boiler switch and see if smell persists.

    The odorant in LPG is pretty pervasive especially for sensitive noses.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    TT's have a factory union inside, by the gas train. Check that closely.
  • oak
    oak Member Posts: 22
    I will check that union; but also we will try that gas shut off test.
  • Zman
    Zman Member Posts: 7,561
    Bob Bona said:

    TT's have a factory union inside, by the gas train. Check that closely.

    I have seen that leak as well...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Bob Bona_4BobbyBoy
  • plumbgod
    plumbgod Member Posts: 9
    I would check at the venture and make sure that you are not getting a back draft through that. If you are that could cause a smell.
  • Tim McElwain
    Tim McElwain Member Posts: 4,612
    I would advise you have your propane supplier do a pressure test to eliminate and possible leaking before the controls with them shut off. If that shows no leak then test with them in the on position but not calling for operation. If that shows a leak then it is definitely in the controls. Then as much as you can by process of elimination do a pressure test by putting a digital manometer on the control and pressurize and see if the pressure drops after shutting off the main gas feed.

    Sometimes by the way excessive ethyl mercaptan odorant in the gas can cause this to happen. It will take a long time to disappear after operation.
  • oak
    oak Member Posts: 22
    As this problem lives on it is showing new behaviors. I am not getting consistent ignition and I get a soft lock many times in 24hours. Sometimes the boiler reset works and sometime not. The smell of propane comes after failure to fire and later on it shows up when the boiler has been idle. The amount of propane is inconsistent; sometimes very strong and long lasting, other times weak and short lived. It can happen a couple of times an hour or not for several hours. Its a TT combi boiler, Excellence 110.

    Yesterday I cut down the PVC fresh air supply termination stack to ensure it is 12" lower than the exhaust and swung the intake elbow around so it's 36" upwind of the exhaust. Trying to prevent any possibility of recycling unburned propane that way.

    Yesterday a sudden ignition occurred with a loud whump (like the sound of gasoline igniting when you soak a brush pile with fuel and light it with a match). I heard the whump outdoors, coming from the exhaust stack.

    Seems there is a gas regulating valve mechanical or a control failure. Boiler may or may not fire when DHW is called for. May or may not fire after manual resetting. Smell of propane happens inconsistently; sometimes after failure to ignite and mostly after being idle for some time.

    Now its progressing to the overabundance of propane at the time of ignition that caused the whump. Seems a little dangerous.

    The service tech left me the combustion analyser's read out and I see it was set up for Nat Gas, not propane (most of their clients are Nat Gas customers). The boilers O2 level is 4.2 % but TT technical support (over the phone) says it should be around 3.4 %. I am getting the analysis redone. I will ask the tech to do a gas pressure check. He is bringing a replacement gas valve but I hope we can eliminate that expense (already spent $700 on last week's service call) with some adjustments.

    I did shut off the boiler's own gas supply and the house supply regulator. After 24hrs, there was no more propane smell. TT says that there may be a faulty regulator as the propane smell should not have lasted that long. Possibly, but shouldn't the boiler regulate its own intake of propane ... or can there by a over-matching pressure coming from the supply side that defeats the boilers controls?
  • oak
    oak Member Posts: 22
    Have you checked (and I mean really really checked) ALL of the gas fitwwtings in the room? If the unit had its gas supply turned off and you still smelled it, then it may not be the unit. Then again it may be. Propane smell lingers for a long time.

    Some things to consider:

    Is the combustion air termination outside anywhere near your LP tank, 2nd stage regulator, any gas piping at all? The smell could be coming from there, especially regulators. They have vents on them that may realease a small amount of gas periodically.

    Any old style gas shutoffs with a little ear instead of a handle?
    like this:

    http://www.google.com/imgres?imgurl=http://www.diychatroom.com/attachments/f7/53954d1342141351-leaking-ball-valve-gas-line-112-003.jpg&imgrefurl=http://www.diychatroom.com/f7/leaking-ball-valve-gas-line-150061/&h=154&w=174&tbnid=4R4ANKShqd7tVM:&docid=2UXiMwocY9xTtM&ei=6pPOVcS2Hs-VyAS6pry4BA&tbm=isch&ved=0CCkQMygMMAxqFQoTCMTTk4T2qccCFc8KkgodOhMPRw

    Those seal with a greased brass against brass seal that needs to be serviced every now and then by re-greasing and tightening (though it is more economical most of the time to replace the valve).

    How was the gas meter inconclusive, did it detect gas but was unable to pinpoint the source or did it not really detect any gas? I almost never use a gas meter to find leaks. Don't get me wrong, they have their uses, but I feel that sometimes they are too touchy and are bad at identifiing specific leak sources. Using a good bubble solution is almost always faster IMHO. Dish soap and water is not a good leak detector. While it may find big leaks, it will dry up and evaporate before it finds the really small leaks. I recommend using this stuff, though any good bubble leak loacting fluid will work:

    http://www.amazon.com/Nu-Calgon-4184-24-Fluorescent-Leak-Detector-Qt/dp/B0056BOUHM

    It will stay in place for a long long time withouth evaporating, it forms and holds bubbles for a very long time, and allows you to see small leaks easily if you wait long enough. I have seen this stuff show a very small leak with a big blob of bubbles (size of a golf ball) after I sprayed it on a Thursday and was back to the job on Monday to check my radiant tubing. That leak was so small that the drop in the pressure gauge over that time period was less than .5 psi. It works.

    I have been in several situations like this where the apperance of an intermittant "gas leak" confounded me and several others for days and days until we found the evaporated floor drain under the water heater, dead mouse in the bathroom fan vent (true story!), or other smelly thing mistakenly thought (by me too) to be a gas or propane leak.

    The only way to solve these is to start eliminating things one at a time. Thouroughly check all piping that you can get to with bubble solution, or as Tim says have your supplier perform a leak check. dump water down any floor drains, tubs, sinks, clothes washer boxes, etc that do not get used frequently. Check under cupboards, in corners, places where you could suspect a small dead rodent of hiding from view. I suspect after looking for six hours for a leak on the unit, it may not be the unit (though of course it may be). Keep looking in different places and eventually you will find it.w

    Best of luck!

    ---------------------------------

    Delta T

    This is small building (an all season cottage - retirement home). 1000 gal buried propane tank, pex to the regulator mounted, which is mounted on the north wall with outdoor/indoor access at this location, connected to the boiler with a gastight line run of about 12 ft, with an inline brass T supply to the kitchen range and one isolating ball valve 12" up-stream of the boiler.

    Four times and three different people using industrial leak spray and one time using a sniffer (leak detector) to check every fitting and joint. The regulator pressure setting is correct, and no bubbles appear at any joint/fitting. The ball valve is 3 years old.

    Fore sure, as you indicate, the sniffer is very sensitive and it set off an alarm at the bottom of the boiler box and at the venturi which is where the gas seems to be escaping.

    I am not adverse to and even would be happy (its much cheaper) if the issue were the supply outside the boiler, but all our noses including the service tech and the system's designer/installer agree the propane smell is in the box and it falls out an access port at the bottom. Sometimes strong and long lasting; sometimes weak.

    The TT technical staff say there is no way the gas could be present in the boiler 24 hrs after the supply was shut ... if the valves are working. Makes sense, and we will do a pressure check, and I will ask the propane suppler to check the regulator. But the pattern of leakage (read above) seems to indicate an internal control or mechanical failure. How can a faulty supply side pressure not be overridden by the boiler's own controls? That would mean the boiler is vulnerable to irregular regulator performance with varrying pressures that lead to insufficient gas sometimes (won't ignite) and too much at other times (the whump at ignition and the frequent release of gas inot he house when the system is idle)?

    Thanks
  • Shane_2
    Shane_2 Member Posts: 191
    edited August 2015
    Hi Oak,

    Might be a little late to the party, but one question.

    Has the igniter been checked? I had a TT Solo with some similar symptoms a few years back. This one was natural gas- but we were getting some gas smell after tries for ignition. Some whumps, and some soft lockouts. Igniter had a crack in it.

    I would still do as Tim suggested, checking pressure etc. , just wanted to throw that in.
  • oak
    oak Member Posts: 22
    Shane ... the igniter was changed two weeks ago, along with the flue temp sensor. That was the first thing folks assumed was the issue: a corroding and deforming igniter. Boiler started easily after these changes but the propane smell returned about 1/2 hour later and then things got even worse.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    edited August 2015
    I agree, sounds like sewer gas to me. If you have cast iron or copper drains, and don't have a neutralizer on your condensor, failure is imminent.

    The fact you weren't set up for LP is also something that will produce a lot of bad strange odors, the ones that burn your eyes (aldehyde's?), and a lot of hard lights, and flame outs, which usually end up locking the appliance out (loss of flame signal during call for combustion)

    Missed ignitions will launch a soft lock out, which retries after an elapsed time. This too could create bad odors in the appliance exhaust.

    I'd also (carefully) spray soapy water on all of teh manifold flange connections on the air gas fuel pre and post mix connections. I've seen gaskets fail on this components and leak fuel into the vestibule, and no one even knew there was an issue... Due to post purge, the fuel odor never made it into the room.

    No leak is a good leak when it comes to fuels. No leak is a good leak with aything that's supposed to be on the inside of any pipe for that matter :wink:

    ME

    PS, someone needs to invent an inexpensive inflatable plastic liner to fix the lost trap weirs in LOTS of boiler rooms so the trap levels can be maintained. Still need to neutralize to avoid further damage to buried metal drainage pipes, but could at least keep the stanky sewer gas out. Have you ever seen what burning sewer gas laden with VOC from the use of chlorines (Clorox, etc) does to the combustion process and the metals associated with that process?

    It is not pretty.

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • flitchplate
    flitchplate Member Posts: 6
    The big day is Monday: TT technical support and local servicing company will be on the phone together while standing in front of the boiler.

    ME .. Must be pretty dry in your neck of the woods.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Colorado, Denver, high plains, arid desert, normal back ground rH is 5 to 7%. Dryer than a pop corn you know what... ;-)

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • lchmb
    lchmb Member Posts: 2,997
    curious...how old is the boiler, has it been serviced and was it set up by analyzer when it was first installed? If so did they leave the readings?
  • oak
    oak Member Posts: 22
    Total mystery - problem solved ... but no one understands how???!!!

    Its the 4th season for this TT - Excellence110 combi boiler. The tech is used to working on city boilers and forgot to change his analyzer setting.

    So how did it get fixed:

    After first local tech visit (new igniter, new temp sensor and tech error mis-calibrated boiler to natural gas instead of propane) things went from bad to worse. I called TT directly.

    1. TT service via telephone said to cut down the fresh air intake (on roof) so I lowered it another 6" and turned the sweep so its about 12" below exhaust and 3' up wind. That did not solve the gas puffing/smell problem (it was coming out of the venturi).
    2. TT said to recheck all fittings, joints and connections. We did it with spray and with electronic sniffer. Nothing.
    3. TT said to pressure check the supply and regulator and isolation ball valves. Manometer on the downstream side of the regulator said it was supplying 9 WCI (water column inches) so we turned it up to 11 WCI. We also shut the isolation valve off at the regulator and at the boiler and monitored pressure for a day ... it did not drop.
    4. After these tests and slight pressure adjustment, the propane puffing stopped and the soft lock out (re-firing when calling for DHW) ceased. No smell and no refusal to fire!!!! (my brother in law has the equipment).
    5. On Monday the local service tech arrived with a new gas valve. I asked him to check the current valve screen and venture port for dirt before changing it out. It was clean. Se we did not install the new one.
    6. He pressure washed the HX (using garden hose at about 65psi) and got about 7 gals of really dirty water and solids before it ran clear. WOW, it was filthy. Seemed mostly to be insect bodies/debris, farm field dust, lawnmower dust (I mow with 48" Lazer Z-e eXmark) and I guess also some construction dust (i.e drywall dust, saw dust). I though these condensing boiler were "self-cleaning".
    7. We tried to recreate the propane smell but problem it would not return after gas pressure tests.
    8. The service tech recalibrated with analyzer on correct propane settings.
    9. So far, no propane smell returned, burner ignites smoothly (no backfire or soft lockout).

    Why the problem went away is a mystery. Perhaps the opening and closing of the gas ports and fiddling with the supply cleared some dirt out of the gas valve screen or seat? My hunch is that an insect body part was involved. Flies, hornets and other flying critters are forever showing up inthe condensate. I can easily see how particles could dirty the gas valve seat. Fresh air intake screen is spec'ed for 1/4". I wonder if I could safely go to a smaller screen size?

    Thanks for your help






  • oak
    oak Member Posts: 22
    opps, celebrated too soon; two days since I posted the all clear, and boiler went into soft lock out, smell of propane back, will bite bullet and replace gas valve.
  • JUGHNE
    JUGHNE Member Posts: 11,042
    It would be interesting to look inside that gas valve and see if there is any debris under the seat. That might not have given you reliable 100% shut off.

    I think the term of "bubble test" would apply for checking the outlet when it is supposed to be shut. Don't know how you could have done that with that type of valve.
    Canucker
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
    I am waiting for the day when someone invents a visual smell indicator. (maybe someone already does?) Kind of like a FLIR camera, but instead of seeing infrared, it can see different kinds of fumes. Would be great for finding gas leaks and even sewer odors. Now THAT would be a cool tool to own!
    Rick
    Aaron_in_Maine