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Thread: sequencer

  1. #27
    Join Date
    Dec 2012
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    columbus, OH
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    Quote Originally Posted by 54regcab View Post
    The ideal solution is to use a thermostat with multistage capabilities that would only bring on the extra banks of heat strips as needed. The 1st 10KW could be brought on by one contactor through W1, the 2nd 10KW contactor brought on by W2.
    If a multistage thermostat isn't practical time delays or outdoor thermostats could be used to control when the 2nd bank of heat is activated.
    Another strategy with heat pumps involves setting up one 10KW bank of heat connected to W1 of the thermostat and the other 10KW bank being activated by the defrost board of the heat pump. If the heat pump can't keep up the thermostat will call for 10KW heat, when the heat pump goes into defrost the other 10KW will come on. Once the heat pump catches up electric heat is dropped. A simple wiring change achieves this, no additional parts required.
    Im not disagreeing with a word you just said. Your obviously more knowledgable on the subject than me. I was commenting on a earlier post in the thread were someone said they always change seq. with contactors when theirs a problem. I wouldnt thank thats a good idea especially when you suspect ambient heat is preventing the seq. from opening.

  2. #28
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    Dec 2012
    Location
    columbus, OH
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    Quote Originally Posted by 54regcab View Post
    Peak demand is figured over a 15 minute period, not at any one instant. It only affects those who have smart meters with peak pricing plans and certain commercial customers. IMHO it's better to split the heating load into stages controlled by the thermostat.
    To clarify what i was saying the post i commented on didnt mention staging. And as you said electric plans vary we dont know this homowners plan, nevertheless sequencers werent designed to keep breakers closed since theirs no difference on start up amps so i assume their designed to control peak wattage. Plz correct me if im wrong but most pairs of resistance heaters are on a separate breaker than the blower.

  3. #29
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,508
    Normally there are 2 60A double breakers. One set controls the blower and the 1st stage of heat strips, the 2nd set controls the 2nd stage of heat. Air handlers typically use W1 and W2 for heat, one terminal per bank of heat. A 2 stage thermostat can bring on W1 most of the time, and only kick on W2 when W1 can't keep up.

  4. #30
    I'm working on a downflow electric furnace about 20+ yrs. old. The heat wouldn't shut off, and t-stat checked out good. I replaced sequencer, then I get same call 12 days later and same problem.
    It's only a 30,000 btu furnace.
    Would the limit switch cause the overheating of sequencer?............. Tomorrow I will try a continuity test on limit switch and elements.
    ANY SUGGESTIONS OUT THERE?

  5. #31
    Join Date
    Jul 2009
    Location
    Columbia, MD
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    4,483
    If you have low airflow and the electric compartment is too hot, it could keep the sequencer in the energized state

  6. #32

    Thnx

    Quote Originally Posted by gravity View Post
    If you have low airflow and the electric compartment is too hot, it could keep the sequencer in the energized state
    I put my thermometer inside compartment and close the cover to see what it reads. I've never ran into that in 18 yrs. I was thinking on putting a small piece of ceramic tile between the base of sequencer and the furnace wall.
    The blower is on Medium for heat and high for cooling right now.

  7. #33
    Join Date
    Aug 2009
    Location
    Beatrice, NE
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    2,520
    Quote Originally Posted by Puzzle50 View Post
    I put my thermometer inside compartment and close the cover to see what it reads. I've never ran into that in 18 yrs. I was thinking on putting a small piece of ceramic tile between the base of sequencer and the furnace wall.
    The blower is on Medium for heat and high for cooling right now.
    The unit was designed to work properly with the sequencer in that location. You should not have to do anything to the sequencer unless it's bad. Fix the problem not the symptom.

  8. #34
    Join Date
    Jul 2009
    Location
    South Carolina
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    3,366
    Quote Originally Posted by Puzzle50 View Post
    I'm working on a downflow electric furnace about 20+ yrs. old. The heat wouldn't shut off, and t-stat checked out good. I replaced sequencer, then I get same call 12 days later and same problem.
    It's only a 30,000 btu furnace.
    Would the limit switch cause the overheating of sequencer?............. Tomorrow I will try a continuity test on limit switch and elements.
    ANY SUGGESTIONS OUT THERE?
    Sometimes a bad blower relay can cause the same symptoms as a stuck sequencer. An amp meter in the right spot will tell you for sure. A lot of times when you shut the power off, a stuck relay or sequencer will unstick for a while.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  9. #35
    Quote Originally Posted by kls-ccc View Post
    The unit was designed to work properly with the sequencer in that location. You should not have to do anything to the sequencer unless it's bad. Fix the problem not the symptom.
    Thnx, but I replaced the sequencer, and the furnace runs like new for about 2 weeks. Today I'm going to check the element(yep, there's only 1) and the limit switch to find out what's overloading the sequencer or shorting it out.

  10. #36
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,520
    I ran into one of these several years ago, went through 3 sequencers before I figured out it was the air flow that was keeping the sequencer engaged. The back panel was hot where the sequencer mounted. made some changes with duct work sealing some holes and cleaning the coil and magic, no more problem.

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