Harman Measuring Draft: 3/8-16 to 3/8NTP or 1/8 Tubing adapter.

lawlopez Posted By lawlopez, Nov 9, 2008 at 3:08 AM

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  1. lawlopez

    lawlopez
    New Member

    Sep 22, 2008
    56
    0
    Loc:
    New Boston, NH
    I have a Harman P61 pellet stove.
    I have a Dwyer Magnahelic .5 inch vacuum/pressure gauge.
    It has 3/8 NTP fittings.
    It comes with 3//8 NTP to barbs for 1/8 ID tubing.

    The Harman has a bolt closing up a place to connect the 1/8 tubing.
    It's location is not found in the P61 manual but the P38 manual.

    This bolt seems to be threaded 3/8-16

    How do I connect a 1/8 ID to it ?

    I'm at a loss unless I just push the tubing into the hole without a fitting.
    I suppose I could do that and temporarily calk it in place.

    The basic problem is that 3/8-16 sould not be used for an air/vacuum port.
    Thanks,
    Larry
     
  2. GVA

    GVA
    Minister of Fire

    Sep 4, 2006
    2,140
    0
    Loc:
    Waxhaw, NC... Formerly North shore Mass
    3/8-16 thread uses a 5/16" drill.
    you just need to put the 5/16" tube into the tapped hole and this is sufficient to check draft.
    most dwyers come with a silicon hose 1/8" id and 5/16" od just dont leave it in there too long.
     
  3. lawlopez

    lawlopez
    New Member

    Sep 22, 2008
    56
    0
    Loc:
    New Boston, NH
    Oh my.I hadn't even thought of using somehting that could take heat !!!
    Thanks a lot.
     
  4. lawlopez

    lawlopez
    New Member

    Sep 22, 2008
    56
    0
    Loc:
    New Boston, NH
    Any idea where I can get some ?
    My Dwyer didn't come with tubing.
     
  5. djarseneault

    djarseneault
    Member

    Oct 5, 2008
    234
    0
    Loc:
    Eastern Connecticut
    You don't need to check the draft when it is hot. The draft readings in the manual are for a cold stove.
     
  6. lawlopez

    lawlopez
    New Member

    Sep 22, 2008
    56
    0
    Loc:
    New Boston, NH
    Yup.

    I wanted to see if there was much change when it was actually running.
    I foundsome tubing which worked pretty good.
    It was 5/16 OD but 1/4 ID so I removed the fittings from the gauage.
    And used it with no fittings at both ends.

    I welded the tube I used to the stove and couldn't get it out !!!

    I got it out by using a torch on the inside.
    Didn't take much. Just a touch. Came out clean.
    I was cracking up. What a dummy.

    I have a lot of draft.
    Always more than .5 inches.

    How do you adjust it ?
    There is nothing on the control board.
     
  7. HBW3

    HBW3
    New Member

    Nov 8, 2008
    7
    0
    Loc:
    MARYLAND
    I have a p61-a that has a small opening for a straight screwdriver to adjust combustion blower speed.
    Mine would not get below .56 at low draft.
    If you have this adjustment it is to the right of the ignitor statis light.
    Set feed to test, turn on stove,pellets feed for 1 min then stops feeding.
    Combustion blower will alternate from low to high draft every 1 min or so.

    I have set my meter up also while running.
    I drilled out another bolt and attached copper tubing to it.
    I used about 18" of tubing and coiled it.
    Hooked up therubber tubing that is about 3' long.
    The gauge works fine during operation.
    I keep the gauge about 4' from stove on the floor off to one side.
     
  8. lawlopez

    lawlopez
    New Member

    Sep 22, 2008
    56
    0
    Loc:
    New Boston, NH
    My P61 has the hole in the sheet metal.
    It has a place on the circuit boad for adjustment.
    It doesn't have the adjustment device soldered to the printer circuit board.

    Your P61A is adjustable, my P61A is not adjustable.

    Did adjusting it down decrease the feed rate on low settings ?

    Good job on the copper tubing.

    Larry
     
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