HIGH TEMP VENT SAFETY SNAP SWITCH

Discussion in 'Pellet Stoves, Pellet Fireplaces, Pellet Furnaces' started by Snowy Rivers, Nov 5, 2019.

  1. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    With the new controller working flawlessly I was still concerned about the lack of a good way to protect the stove (AND THE HOUSE) from an over fire condition....be it a timer failure that resulted in an uncontrolled fuel feed, or a mistakenly set heat range control....that resulted in excessive vent pipe temperature and extreme overheating of the stove....

    Decided to add a simple manual reset type snap switch in the auger feed circuit.

    Built a little bracket that clamps to the vent pipe and has a 250 F manual reset snap switch that fits in a machined hole in the bracket....the snap switch contacts the outer jacket of the vent..

    Normal running temperature of the vent is about 150 to 160 F and that's with the stove putting out good heat.

    So 250 F is still safe as far as temperature goes....buttttttttttttttttt things should not be that hot...

    Just a good idea me thinks to add this little extra layer of safety.

    Very easy to plug the wires into the auger feed circuit wiring and good to go..:yes:

    The vent pressure sensor switch is at the rear of the stove and will open the circuit to the auger if the vent becomes plugged up.... the pressure switch is on the neutral line to the auger motor and this line can run through the new snap switch.....:thumbs:
     

    Attached Files:

    Earl764, brenndatomu and ivanhoe like this.
  2. don2222

    don2222

    Joined:
    Nov 10, 2013
    Messages:
    2,361
    Likes Received:
    2,846
    Location:
    Salem NH
    Hi Snowy
    Those Hi Limit Switches are usually on the back of the firewall inside the stove.
     
    brenndatomu likes this.
  3. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Yes
    This stove has one there...but it is on the air plenum to shut down the unit if the convection fan stops running. (If the fan is running the stove could reach a very high temperature before the inside snap would ever open)

    That one is in the loop on the new control...also there is one in the OAK air inlet to detect a burn back....also in the loop with the new controller.

    Those two snaps are in series with the Latchout relay and if tripped ( Auto reset type) the latchout relay will open and shut the entire unit down BOOM PLOP DONE....and require the reset button to be pressed to get the stove going...

    STOVE OUT AND NO EVIDENCE OF A POWER OUTAGE (Clocks blinking)

    One of the high limit snaps has likely opened.

    The new additional snap monitors the vent temperature and is a mechanical reset type and if tripped the stove will simply cool off and shut down via the low limit snap opening...

    Here is the finished item.

    I machined the bracket a bit ago so the snap switch has a good firm contact with the vent pipes outer jacket.
    All that's left is to add the wiring harness from the junction block to the snap switch..
     

    Attached Files:

    Last edited: Nov 6, 2019
    ivanhoe and brenndatomu like this.
  4. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Wrapped up the new safety switch install this morning.

    All wired in and good to go.

    Turned out to be very quick....simply tied it in series with the exhaust pressure switch circuit..

    Unplugged the neutral from the pressure switch and connected it to the new high temp switch and then plugged the remaining wire from the new switch back to the pressure switch.

    Boom plop done.

    Thinking about a little stand off from the new bracket to fasten a wire retaining clamp to, just to make sure the wires at the snap switch do not get yanked during cleaning around the stove
     

    Attached Files:

    ivanhoe and brenndatomu like this.
  5. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    I was snooping about looking for some stuff and stumbled onto a nice little piece of perforated metal (Came from a light ballast kit) the was perfect for making a little hanger for the new switch assembly.

    Drilled and tapped a hole in the bracket and mounted things.

    All sweet now

    The coiled poly wire wrap gives good protection to the wire inside.....:yes:
     

    Attached Files:

    ivanhoe and brenndatomu like this.
  6. don2222

    don2222

    Joined:
    Nov 10, 2013
    Messages:
    2,361
    Likes Received:
    2,846
    Location:
    Salem NH
    Did you consider a surface mount Hi Limit switch?
    Easier than drilling a 3/4” hole and it works by the heat contact thru the metal, even the air stream mount will not work if the metal to metal contact is not there! I learned that from a Lennox Whitfield T300p with an air stream mount snap disc with 2 strip mounting screws! It just did not work until I put some larger self tappers in and made it a snug fit!
     
    ivanhoe and brenndatomu like this.
  7. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    I looked at several options.

    My setup mounts the snap in the bracket with the face of the snap firmly against the outer jacket of the vent pipe.

    No holes in the vent...just wanted to monitor the surface temperature of the vent.

    150-160 F is normal on the highest setting we use....so grabbed the 250 F snap

    This gives plenty of safety margin....
     
    ivanhoe and brenndatomu like this.
  8. badbob

    badbob

    Joined:
    Apr 23, 2014
    Messages:
    2,186
    Likes Received:
    8,703
    Location:
    bozeman pass,park county,MT 6500'
    I love your thoughts and work,with logical safety.Keep up the great work.
     
    ivanhoe and brenndatomu like this.
  9. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Thanks BB
    When it comes to safety with FIRE yeah buddy.

    Over the past 27 years we have heated with pellet stoves using the nut shells.

    We have had a few close calls related to failures in the stoves that was directly related to the design of the controls.

    We had a draft fan fail and things got a bit smokey, but we were home and were able to handle it..

    The room air fan speed control went buzzwhack back in Feb...The failure happened while we were here and so again nothing bad. (Fan stopped)

    While designing the new controls I took into account the various failures and several other possible scenarios that could lead to bad things happening, and designed safeties into the system to simply shut the entire stove down.

    Even shutting off with a fire burning will normally only result in a little smoke smell in the house....but nothing of any real worry.

    Fuses are in the circuits of both fans and the auger....the factory had one small fuse on the board, but it would not prevent the board from frying if a fan motor shorted.

    The over temp snap switches were self resetting and would not stop the stove from trying to restart once it cooled a bit.

    The new equipment shuts the stove off and requires human intervention to restart.

    If the heat plenum over heats, the snap will open and the latchout relay will open and shut the entire unit off.. (A manual reset button must be actuated to restart)

    If the vent temp passes 250 F the manual reset snap opens and stops the auger......The manual reset type snap must be manually reset after figuring out what happened..

    If any fuse blows it will cause one of 3 relays to open which shuts off the power through the latchout relay....again SHUT DOWN OCCURS.

    Tried to think of all the what if things.

    If its not right SHUT IT OFF....Let the Hoooooman figure it out... :yes:
     
    Last edited: Nov 7, 2019
    ivanhoe, badbob and brenndatomu like this.
  10. wildwest

    wildwest

    Joined:
    Jul 21, 2014
    Messages:
    20,231
    Likes Received:
    75,606
    Location:
    Wyoming high plains
  11. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Goterhandled.....
    I think it's just an older Advantage 2

    Sadly many older stoves get hacked up and modified by folks with little idea about what they are doing....

    Hopefully the fella who posted will get us more piccy's.
     
    ivanhoe and wildwest like this.
  12. wildwest

    wildwest

    Joined:
    Jul 21, 2014
    Messages:
    20,231
    Likes Received:
    75,606
    Location:
    Wyoming high plains
    You are so kind Snowy, always generously sharing all your immense know how. Kudos :tip:
    :handshake:
     
    ivanhoe and Snowy Rivers like this.
  13. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Thank you

    Forums like this are the place to share with others.
    I love to share knowledge....its a commodity that once it's lost it's gone.
    So much knowledge in the minds of many simply goes to waste as they get older.

    I am trying to pass on all I can to my Son in law as far as machining and building things, wiring and such too.

    The kid is a Captain on the local fire dept, really good at what he does and a go getter.

    But it's way too hard to just pick up all this knowledge easily.
    My life has lead me down many paths and into so many different vocations that are very diverse.
    A shame not to share it....
     
    PelletHound and ivanhoe like this.
  14. ivanhoe

    ivanhoe

    Joined:
    Oct 18, 2013
    Messages:
    2,705
    Likes Received:
    10,720
    Location:
    Northern Ontario
    You're the best Missy Good Wench :thumbs:
     
    PelletHound likes this.
  15. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Thanks....
    I try...:yes:
     
    jtakeman, ivanhoe and PelletHound like this.
  16. PelletHound

    PelletHound

    Joined:
    Oct 4, 2014
    Messages:
    593
    Likes Received:
    3,634
    Location:
    SE Ma.
    You are an inspiration to all of us.I love how you solve problems.That's a real talent.:yes:
     
    jtakeman and ivanhoe like this.
  17. Snowy Rivers

    Snowy Rivers

    Joined:
    Nov 15, 2015
    Messages:
    2,078
    Likes Received:
    9,038
    Location:
    Newberg, Oregon
    Thanks P hound.
    I try hard.

    WHAT DO WE NEED TO DO?
    WHEN DO WE NEED TO DO IT ?
    HOW MUCH? :thumbs:
     
    jtakeman, PelletHound and ivanhoe like this.