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  1. #1
    When my furnace comes on the pilot flame on my fireplace just dies down and then goes out. The other day I actually had the fire going and the whole thing shut down when the furnace came on.

    I tried turning up the pilot light but it only helps a bit.

    They are both on the same gas supply line behind a Maxitrol 325-5 pressure regulator. The furnace runs at 130,000 BTU/HR. Is it just using too much of the available gas and not leaving enough for the fireplace?

    It's a new home (to me) and I don't know if the previous owner had the problem and just never fixed it.

    TIA for any suggestions.

  2. #2
    Join Date
    Mar 2004
    SE Michigan
    Sounds like you need some make up air in that mechanical room or the gas line is undersized.

    [Edited by coolwhip on 10-28-2006 at 07:00 AM]
    To put the world in order, we must first put the nation in order; to put the nation in order, we must put the family in order; to put the family in order, we must cultivate our personal life; and to cultivate our personal life, we must first set our hearts right.
    -- Confucius

  3. #3
    Join Date
    May 2005
    Madison, WI
    gas lines were not sized correctly. You can check it out yourself if you wanna learn how.

    Download the design guide, it has sizing charts for black iron pipe in there also. Not sure if you have CSST, black pipe or copper.

  4. #4
    Join Date
    Feb 2004
    What kind of venting? Is it B-Vent? Is it vented into a chimney? Is it vented in common with the furnace? Is it direct vented?

    How old is the house? What type furnace and how is it vented?

    Gas lines may well be undersized. But you're not the original owner so this is not a new home. If pipe sizing is the cause then this situation must've existed right from day one, which is kinda doubtful.

    Have a glance at the gas shut-off valve by your meter to make sure it's in the full on position.

    Whether venting, combustion air, or pipe size, it sounds like something that should be professionally checked!

    Question authority!

  5. #5
    Join Date
    Jan 2006
    Powell River, BC, Canada
    How old is that Maxitrol regulator? It may need replacing. Have a pro come and check the gas supply pressure and pressure drop with appliances running. Pipe size may be ok, but pressure out to lunch.
    Where are you? Are you done yet? I got ONE more call for you.....

  6. #6
    Join Date
    May 2005
    Madison, WI
    Yes, true... the lines might actualy be sized OK but what you said points to some sort of a pressure problem. When the furnace kicks on the inlet pressure on the fireplace probably drops well below its minimum causing it to go out.

  7. #7
    OK. Here's everything I now know...

    The home (apt) was built in 1997.
    It's at an altitude of about 6000' (if that matters)

    The pressure regulator is marked 9-06 (I'm guessing that's a date?)

    The fireplace is a direct vented Heat-N-Glo model SL-36.
    The label says it needs between 5" and 14" WC with a manifold pressure of 3.5" WC.
    I looked at the gas meter with it on and it was using 20 CFH.
    It's about 40' from the pressure regulator, connected by 3/8" flexible line.

    The furnace is actually a boiler, a direct vented Heatmaker HW-M2-130.
    The manual says it works in the 4-13" WC range.
    I looked at the gas meter with it on and it was using 107 CFH.
    It's about 4' from the pressure regulator, connected by 1/2" flexible line.

    Those are the only 2 gas appliances in the apartment.

    Thanks for all the suggestions.
    I'll call someone next week to do the pressure tests and I'll post the results.

  8. #8
    Join Date
    May 2005
    Madison, WI
    Seems like you should be fine with the line sizes, if the regulator is set for a high enough outlet pressure. Hard to say without seeing it physically. I do cringe whenever I see 3/8" line though, always afraid it will not allow enough BTUs. We always run 1/2" line just to be safe and so we dont have to crunch all the numbers every time.

    On a side note, it is possible the line going from outside to the regulator is not large enough.

    Have someone test the inlet pressure of the fireplace with nothing running, then turn on the fireplace, then turn on the furnace. Note the differences in inlet pressures.

  9. #9
    Join Date
    Feb 2004
    Make sure the line valve is not partially closed.. have seen this type of problem many times. If as you stated...when burner comes on and the pilot shrinks, that's where I would start

  10. #10
    They measured the gas pressure at the boiler. It was 7.8". They adjusted the line pressure regulator to increase the pressure to 11.4". It made no difference. The fireplace pilot light still went out when the boiler came on. They switched the arrangement of the piping of the fireplace & boiler. That made no difference. They disconnected the gas pipe at the fireplace and felt for wetness. There was nothing. They said it was still possible that there was water in the gas line between the regulator and the fireplace. The suggestion was either 1) a new line pressure regulator that went up to 14", or 2) hooking up an air compressor and blowing out the pipe. The estimate was an additional $300-$400 for either of those options.

    Gee, I'm still curious, but not quite that curious :-)

    Maybe the best thing to do at this point is just to replace my standing pilot with an intermittent one. At least that way I won't have to fiddle with knobs and buttons under the fireplace every time the pilot goes out :-)

  11. #11
    Join Date
    Jan 2005
    7.8"w.c. at the boiler, adjusted to 11.4"w.c ? Natural gas system unless your on a 2psig system the maxium allowable pressure is 7"w.c downsteam of the meter with a 1" allowable pressure drop ,so if you had 7.8" at boiler(upsteam of control valve) you're ok. What was the pressure at the fireplace control? put a gauge/ manometer upstream of the contol and check static pressure, then fire up both appliances and monitor pressure, does it drop off? Possible obstruction in fireplace line..dirt/mud in line? All these checks should be done by a qualified/licensed gas tech, not a diy project!

  12. #12
    I asked the pros about checking the pressure at the fireplace and they assured me it would be the same as at the boiler. And they added ... "of course the pressure will drop when we turn the boiler on - that's why the pilot is going out! (Duh!)" I didn't ask, but assume it's a 2psi system, which is why you have the Maxitrol, no?

    How about I buy another Maxitrol 325-3 and rearrange my pipes so that the fireplace and boiler are each on their own dedicated 7-11". Would that work?

    Of course, I'd need to borrow a monkey wrench and an adjustable wrench so I could loosen and tighten the pipe fittings (just like the pros I watched today), but I bet I could do the whole thing for under $35 :-)

    BTW, these "pros" who came today have 22+ years experience, were recommended to me, and have no complaints on file at the BBB over the past 36 months.

  13. #13
    Join Date
    Jan 2001
    Pacific Coast of Canada
    I can't believe they didn't check the fireplace pressure.
    Something doesn't sound right with the line sizing, we would never run a furnace and a fireplace 40' away on one reg.
    Trust me, I know what I'm doing.

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