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Slightly puzzling behaviour of a Carlin...

Jamie Hall
Jamie Hall Member Posts: 17,841
probably nothing to be concerned about, but being naturally curious one would like to know what's happening!



Almost always, when the thermostat calls for heat, the burner does its pre-purge thing, then fires up and runs along merrily until the thermostat is happy or the vapourstat says stop.  Then the burner shuts off and the system does its post-purge.



However, once in a while -- and only at the beginning of a cycle, not when cycling on the vapourstat -- the thermostat will call, the burner does its pre-purge thing, then fires up -- and a few (maybe 15?) seconds later it stops completely.  No post purge.  Thermostat still calling.  Then a in a few more seconds -- never timed, 30?  a minute?  Not sure... -- the burner starts a pre-purge, then fires up and runs along merrily.



I've never managed to be in the boiler room when it does this (you can hear it, which is how I know, from the rest of the building) so I have no idea which, if any, of the LEDs on the control are lit/blinking/whatever when it does this.



The boiler is a Weil-McClain 580.  Burner is a Carlin 301CRD-W, 2.75 gph nozzle, pressure at 150 psi, Carlin control.



What is it doing?  Is this more or less normal, or should I be slightly concerned that one of these dark cold mornings it will just decide not to fire up?



Thanks...
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England

Comments

  • meplumber
    meplumber Member Posts: 678
    Sounds like a primary or cad cell thing.

    Jamie, I would start by looking at the cad cell and primary.  Something is causing it to drop the call for heat.  That leads me to the primary.  If it were the cad cell you would most likely be getting intermittent lockouts. 
  • icesailor
    icesailor Member Posts: 7,265
    edited January 2011
    Carlins:

    Something to look into:

    That probably has a 602000 control.

    Put an ohm meter on the FF terminals. I'm not sure if you can just clip the leads to the FF terminals with the cad cell leads on. I always jump the FF terminals and run it like I am testing the control with the leads directly connected to the cad cell wires. The 602000 control will lock out on 1600 ohms. If you are running 1400 ohms, or some high amount, if the flame pattern changes because of draft or something you will not see and the control sees it, it will drop out and do a retry. I'm not sure if the red light comes on because it really isn't a lock out. It can fire on and off like this for some time as long as the fire time goes all the way through the cycles and runs for a few minutes. The control doesn't recycle unless the limit shuts off the control. Set up properly, you can get it down to 300 or 400 ohms. Sometimes, you can't but under 1000 keeps it going.

    Then, there is a trick. Sometimes, the blast tube is dirty and/or dark. Some have found this condition and had high ohms. Painting the inside of the blast tube white or silver will reflect enough light to the eye to bring the ohms down. The dark, dirty tube absorbs light and the lighter colors reflect light. One burner is painted white or silver inside to help this.

    I had a Carlin that had this problem with a power venter that I took on and it did it for years. It would drop out while running for no apparent reason. This is how I found the problem.

    And it wasn't the control. Many controls were put on it by others and myself.
  • Jamie Hall
    Jamie Hall Member Posts: 17,841
    Thanks Ice!

    Sounds quite plausible; I'll give that a try.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • World Plumber
    World Plumber Member Posts: 389
    Domestic hot water.

    Jamie: Do you have a tankless coil on the unit with an aquastat? I had one that dove me craze for 2 years the limit contacts were sometimes not letting the full voltage through and the unit would run or not run depending on how those contacts closed. Finely I got there one day the lights were lit in the control but when I measured the voltage I only had 57 volts when I check the voltage when it would run I has the full 120 volts. You probably don't have a limit, but you could have another contact acting up.
  • Jamie Hall
    Jamie Hall Member Posts: 17,841
    Could be a contact somewhere...

    no, there's no aquastat, but... I think I'm going to have to figure out how the control is supposed to work!  What really puzzles me is that there is no post-purge after the quick shutdown.  It just stops.  Period.  Then pauses, then runs the pre-purge again and fires up -- so far, the second time has always been just fine.  I would think it would run a post-purge if it didn't sense flame?  But maybe that's naive... but if it just completely lost power...



    Hmm.  Circuit diagram time, if I can find one.  Keep thinking, though, guys.  It all helps!  Last resort I can get Charlie from WMass down here -- he did the install -- but I hate to bother him.  Busy man!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • icesailor
    icesailor Member Posts: 7,265
    Bad Behavior:

    If it stops like you opened a switch, it is a loose connection. Does it stop dead? It could be a bad service switch. It could also be a bad control. The red wire on a 60200 is powered all the time. The black comes from the limit. The red one has to have power all the time to run the control. If you loose power on that wire, it could do this. Pull the control up and recheck all the connections. Especially the red and black one. The orange one is for the motor.
  • Jamie Hall
    Jamie Hall Member Posts: 17,841
    Ah ha!

    Maybe I'll go look at that!  Never thought of a loose connection.  Should have.  And just enough vibration when it fires up.  Thanks!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • World Plumber
    World Plumber Member Posts: 389
    loose connection / bad primary

    Check the wire connections. If you can't find anything the control could be tripping into recycle when it turns the transformer off. If it not sensing flame you don't want a post purge. The unit doesn't know why it went out. If the motor runs for post purge and the solenoid doesn't close all the way you would be pumping oil in that could ignite and cause  a big bang it something ignited it. 
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,200
    Jamie just give a call

    For you I have the time.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,200
    Any suggestions are welcome

    I am always willing to get input from you guys on these things too.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • Jamie Hall
    Jamie Hall Member Posts: 17,841
    Good grief...

    there are more possibilities here... !



    I'm going to do a little more research into just when it does it's thing, and then get together with Charles on it.  And thank you for your comment, Charles!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • gilligan
    gilligan Member Posts: 18
    lwco?

    believe this is a steam system....some electronic lwco's will do a self- test every 10 minutes or so which will shut the burner down for 30 to 90 seconds. if this happens just after the thermostat calls it may be your issue
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