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Powervent shuts off after running for 1 minute

lukem Member Posts: 1
Have a Tjernlund SS1 sidewall powervent that is 10 years old. It is connected to an oil fired Biasi Boiler. The powervent fan comes on when the Boiler fires up, but after about 1 minute into the cycle the fan on the powervent shuts off. I am not sure how long it has been like this. But the temperature in the boiler room is warmer than it should be, the exhaust piping is sooted up and the boiler is running richer than it should. All of this is because the powervent is shutting off after running for only 1 minute or so. First thing I want to do is make sure the wiring is correct, as I believe my boiler tech cleaned my furnace a year or two ago and rewired the unit (possibly incorrectly). Any other ideas?


  • Weezbo
    Weezbo Member Posts: 6,232
    SOunds like ....

    the puff switch .

    the Tjerland site has someone who used to show up here and they answer questions over the phone.

    quickest way standing in front of the boiler they can make sure you get everything togethe r on the spot.

    there are many kinds of equipment lashed up to side shots , some have pre purge post purge blah blaah blah and the side shots have different dip switch settings for all sorts of parameters.

    newer elctronic equipment can tun off them that way.

    the puff switch is like a prover or safety . it verifies if all is well with the burn and venting

    they can be a chore at times , the type of burner and type of control and the appliance are all useful information .

    Hope that helps in a speedy recovery.


    *~//: )
  • icesailor
    icesailor Member Posts: 7,265
    SS-1 running:

    First of all, the SS-1 and the boiler are wired wrong and not compatible. If the PV motor stops, the burner must stop also. It wasn't ever wired properly. Whomever wired it in the beginning, turned it on, it fired up, and now isn't working. There are safety sequences that must be followed.

    What is the burner control?

    You have a mess on your hands and need a pro that knows what they are doing.

    The so called "Puff Switch" is a fail safe device like a cad cell. If it is open when it goes to start, it will try and then it should close and hold then the burner fires. If it is closed, the control will not allow the burner to start because it knows it shouldn't be running. If the draft switch doesn't pull in within a minute, it shuts off the PV. If it doesn't stop the burner, its mis-wired.

    Get a Professional. NOW.

    Your life and safety is in danger.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,542

    I agree 100%,it's not wired properly,turn it off until it's fixed
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Weezbo
    Weezbo Member Posts: 6,232
    the powerventer ...

    turns on , then the message is sent to the burner . not the other way around .

    the burner may have a pre purge or post purge or both ,

    if the burner runs then the powerventer and then it conks out someone by passed it and has the boiler/ burner feeding it the electrical signal ,

    if the boiler quits when the powerventer is running no big deal , the other way around it is .

    what will happen is that will soot up the burner combustion and the venting .

    there had to be a reason they wired around it , and i think it was because it would shut down because the prover said turn off .

    if a low water says no it wont go , so it should also be wired thru that as well.
  • billtwocase
    billtwocase Member Posts: 2,385
    definitely wired wrong

    sounds like the power vent is powered from the burner on the cad cell relay, if it does have a post purge. Should always be 2 L-1's to any power vent, and someone needs to do a combustion test, if it is sooting. Call a pro
  • Jack
    Jack Member Posts: 1,047
    In addition to the wiring...

    Has anyone serviced the SSI? If the blower wheel is packed and the sensing tube too, you can wire it properly and still get no heat. It is not uncommon for "some" service companies to tune up the boiler and never touch the power enter. They will then righteously tell you they don't service power venters. That was always a head scratcher for me. If the wheel hasn't been cleaned it is not uncommon for it to get out of round and require a new wheel. The UV1controller on that unit will have diagnostics on it and has adjustable pre/post purge built in.
  • icesailor
    icesailor Member Posts: 7,265
    UV1 Controller:

    Drop the cover and look at the UV1 controller. Watch the diagnostic lights to see if they go through their proper sequence.

    When the call comes from the burner controller, it is supposed to make the PV fan start first. Often, there will be very little delay before the burner starts. Because the fan prover switch is satisfied. If the burner motor starts and the SS-1 fan doesn't start immediately or after the burner starts, the SS-1 is wired wrong.
This discussion has been closed.