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  1. #1

    Confused

    I have a Sears/Kenmore gas furnace hot water heating system thats acting erratically.

    What works:

    1.) The house thermostat appears to work.
    2.) I hear the electronic igniter "clicking".
    3.) I hear the gas supply flowing.
    4.) I see and hear the gas ignite and stay lite.

    What does not work:

    1.) The Grundig circulator pump (which makes a humming sound when it operates) does not appear to be operating (no hum, as before).

    2.) The heating system works as described above but seems to cycle on and off without water circulation - the circulator hum is no longer there. In the past, I am 90% sure the circulator pump kicked in whenever the furnace was activated by the room thermostat.

    3.) MOST IMPORTANT: When the furnace is activated (by initially raising the temperature setting of the room thermostat) the igniter lites the gas and the furnace runs for a few minutes, then it shuts down. The new room thermostat setting is completely ignored and little heat reaches the room radiators. STATS: The furnace reads a temperature of about 180 degrees F with a water pressure of about 18 psi.

    I suspect (but I am likely WRONG) the furnace is reaching a top temperature and then cycling off as a protective measure because the pump is not circulating the heated water to the room radiators and returning cooler water for reheating. What I cannot understand is why the pump does not operate. Also, the furnace temperature reading does not appear to be very "high" (high enough to cause a furnace shutdown) or beyond a normal Winter operating temperature.

    Sorry for the long post - just trying to describe the problem.

    Thanks for all your help.

    Steve

  2. #2
    Join Date
    Jun 2003
    Location
    New Hampshire
    Posts
    2,666
    The problem could be the thermostat itself or thermostat connections on the thermostat, or the thermostat connections on the circulator control, or the circulator control itself could be bad, or the 120 volt connections at the circulator control are loose, or the connections at the circulator are loose, or the circulator could be bad or the capacitor at the circulator could be bad.
    If you have a volt-ohm meter and know how to use it, you will figure it out.

    Its even possible that there is air in the zones and the circulator won't pull.
    Chances are the control will only fire off the burners if its calling for heat so that would ELIMINATE the thermostat and connections as being the problem.


    [Edited by oil lp man on 10-05-2004 at 12:45 PM]

  3. #3

    Thumbs up Thanks oil lp man

    Thanks oil lp man.

    I started checking voltages with an ohmmeter and was about to remove the circulator capacitor when...

    I found one loose thermostat connection (left by the furnace man). I tightened it and it looks like its working.

    Seems like its almost always 1 or 2 simple things.

    I'll post again if anything changes.

    Steve


  4. #4
    Join Date
    Dec 2003
    Location
    Kenilworth New Jersey
    Posts
    230
    It`s a boiler NOT a furnace

  5. #5

    Confused CIRCULATOR PROBLEM HAS RETURNED

    My hot water circulator problem returned (likely never left).

    The room thermostat initially turns on the boiler (igniter clicks, gas flow and flame all present and working) and the circulator operates. It all runs fine for about 15-30 minutes then everything shuts down. The initial shut down ignores the room thermostat. Later, it turns on again. Sometimes, everything including the circulator, works. Other times, the igniter kicks in, the gas flows and the boiler lights and runs, but the circulator does not operate.

    Specs around shut off time - Water temp about 185 deg F, water pressure about 13 psi.

    I've checked the electrical connections and they look okay but will check again. I do not think its an air pocket. Its circulator operation related.

    Help appreciated !

    Steve

  6. #6
    Join Date
    Jun 2003
    Location
    New Hampshire
    Posts
    2,666
    When it happens again, if you put a jumper across the thermostat connections of the aquastat control and you don't have power(120 volts) at the circulator terminals at the aquastat control(C1 and C2) then your aquastat control is bad.

  7. #7

    oil lp man

    oil lp man,

    I identified the C1 and C2 (circulator) connectors with black and white wires. Also, I found the thermostat connectors as follows:

    TV: with a red wire
    W jumped to the TV connector
    T with a green wire
    Z with a white wire

    Which two room thermostat wires do I jump (then check C1/C2 for 120 VAC) when the circulator is not working ?

    More info:

    Inside the Honeywell elctrical housing I found a transformer, a (I believe) gas valve relay and a device with a gear in it with (I think) temperature markings stamped into the metal. I carefully checked and found 120VAC current at the line (L1/L2) connectors. Inside the circulator electrical housing I found connectors and a cylindrical device that looks like a electrolitic capacitor. On the outside of the Grundfos circulator there is a 1" slotted screw in the center of the housing that dripped water a bit when I turned the screw counter-clockwise a half turn (retightened).

    Where is the aquastat ?

    Steve

  8. #8
    Join Date
    Jun 2003
    Location
    New Hampshire
    Posts
    2,666

    Re: oil lp man

    Originally posted by stevemason5
    oil lp man,

    I identified the C1 and C2 (circulator) connectors with black and white wires. Also, I found the thermostat connectors as follows:

    TV: with a red wire
    W jumped to the TV connector
    T with a green wire
    Z with a white wire

    Which two room thermostat wires do I jump (then check C1/C2 for 120 VAC) when the circulator is not working ?

    More info:

    Inside the Honeywell elctrical housing I found a transformer, a (I believe) gas valve relay and a device with a gear in it with (I think) temperature markings stamped into the metal. I carefully checked and found 120VAC current at the line (L1/L2) connectors. Inside the circulator electrical housing I found connectors and a cylindrical device that looks like a electrolitic capacitor. On the outside of the Grundfos circulator there is a 1" slotted screw in the center of the housing that dripped water a bit when I turned the screw counter-clockwise a half turn (retightened).

    Where is the aquastat ?

    Steve
    You're scaring me. I thought you had a better idea of what you were doing. The electical housing you are talking about is the aquastat.
    You need to jumper the TV and T terminals.
    I'm done.

    [Edited by oil lp man on 10-11-2004 at 01:00 PM]

  9. #9
    Join Date
    Feb 2004
    Posts
    451
    Your hight limit is shutting the boiler off at 185 deg. Your circ. pump should be running and this is normal. your boiler maintains temperature. if your circ. pump is not running on calls for heat then you should call in a pro.
    Before you criticize someone, walk a mile in their shoes...that way you are a mile from them and have their shoes

  10. #10
    Join Date
    Jul 2001
    Location
    Delaware
    Posts
    1,229
    Grundfos circulator? Is the circulator body hot? If it is, the circulator rotor is probably stuck. A common problem with Grundfos.
    Work is for people who don't know how to fish.

  11. #11
    Just a guess, but maybe the control for the pump is bad, or maybe just the pump is bad...

  12. #12
    Join Date
    Dec 2002
    Location
    Pa.
    Posts
    68
    Gradywhite is right,on the back of the circulator pump is a silver slotted screw.Unscrew it-will get water seepage.The shaft is slotted,take a screw driver and give it a few turns with power off course.Try that.Grundfos is notorious for that.

  13. #13

    Hmm Circulator issue update

    Thanks guys.

    Looks like I scared oil lp man, sorry about that. I am not an expert but I have some tech backround, I listen pretty well and proceed slowly with great caution.

    I did short out the TV and V terminals to test for C1 and C2 current. Before the jumping TV and V there was 120 VAC current at the C1 and C2 terminals but no circulator motion. After shorting out the TV/V terminals there was 0 VAC at the C1/C2 terminals and, of course, no circulator motion. Hope I did not fry something. If I did, I'll live with the consequences.

    The 185 deg F shut down makes sense. If the circulator does not operate, the boiler heats the stagnate water near the aquastat themostat and shuts it down at the aquastat setting. Since the circulator does not supply colder water to the system, the heat in the water just builds up near the thermostat. I checked the aquastat setting - sure enough, it is set at about 180 deg F.

    I am leaning toward the Grundfos UP 26-64F circulator as the core problem. If C1 and C2 are energized with 120 VAC during operation, why is the circulator not operating ?

    I removed the silver shaft screw and turned the the shaft a few times. It seemed to turn pretty easily (I used a very small screwdriver). Then I energized the circulator with 120 VAC separate from the aquastat. I got nothing. No hum, no warmth or vibration on the circulator housing. Looks like a dead circulator or a dead starter. I called a Grundfos distributor. They no longer make this unit so replacing the starter circuit is out. Replacing the starter capacitor may be an option.

    Questions:

    Is there a test to check the circulator starter capacitor ?

    This Grundfos has a pronounced hum that is transferred to the house via the radiators. Can anyone recommend a reliable and quieter replacement circulator that will fit in the above Grundfos installation ? A few rough dimensions: from flange to flange, the Grundfos is 6 1/2" tall and the flange bolts are 3 1/4" apart, center to center.

    Thanks.

    Steve

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