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  1. #1
    Join Date
    Apr 2011
    Posts
    13

    Default Aquastat question

    Here is my issue. I have a fairly new boiler (burnham/beckett - 2003 installed). I have the hogh low temp set at 145-175. The boiler goes on for 4 minutes then off for 6 minutes (i timed it a for a few cycles) When is the boiler suppose to go on as it relates to the low temp? It seems to be going on at around 170 and not below that?? It doesn't seem correct..any suggestions or comments would be helpful. By the way this is an oil boiler.
    Thank you Joe V.

  2. #2
    Join Date
    Feb 2008
    Posts
    200

    Default Re: Aquastat question

    Joe:

    Could you provide the model # of the boiler, & the model # of the aquastat---obtain the model # of the aquastat by removing the cover, & checking for a model #, such as L8124C, etc.

    While you're checking the aquastat model #, make sure you have not REVERSED the two dials that control HIGH LIMIT, and LOW LIMIT: the low limit should read approx 140 degrees; the high limit should read 180 degrees---if these dials are reversed, the boiler will operate erratically.

    Many of these boilers have what's known as a "tankless coil" inside the boiler that provides approx 1-2 gallons of DHW (domestic hot water-tap water) for the sinks, bath, etc.; on such boilers the aquastat is known as a "triple aquastat" and will fire the boiler anytime the boiler water temp falls below 140 degrees or so; in such cases the boiler will fire for 7-8 minutes or so to heat up the water in the tankless coil so that there will be hot water at the taps when needed; these "short cycles" are more common during mild weather (fall/spring/summer); they are not needed by the boiler during the winter because the boiler is always firing to heat the house---this tends to keep the boiler water at approx 160-180 degrees, thus the "short cycles" are not needed.

    Aside from the above short cycle routine, the boiler also has a longer routine called the heating cycle when the wall thermostat senses it is cold in the house & "calls for heat" to the boiler by shorting out its 2 leads---again, the aquastat fires the boiler, but will contine firing the boiler until the boiler water reaches "high limit" of approx 180 degrees (knob dial on aquastat); the circulator will continue to run & provide heat to the house, and this process will continue until the room t-stat opens & no longer "calls for heat"; the boiler burner will shut down but the circulator (pump) usually continues to run for another 10 minutes or so to add a little extra heat to the rooms (override) according to how the t-stat is configured (heat anticipator/differential).
    Last edited by Dobbs; 11-16-2011 at 06:30 PM.

  3. #3
    Join Date
    Apr 2011
    Posts
    13

    Default Re: Aquastat question

    The model number of the boiler is-KV84 AND THE AQUASTAT IS - L4081B

  4. #4
    Join Date
    Apr 2011
    Posts
    13

    Default Re: Aquastat question

    I checked the high and low and they are not reversed...

    The boiler comes on long before the temp hits the low point?? That's with the heat off and only for hot water consuption and not even turning on the hot water....

  5. #5
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,217

    Default Re: Aquastat question

    If I remember right that aquastat has a differential setting. Try setting it higher.

    John

  6. #6
    Join Date
    Feb 2008
    Posts
    200

    Default Re: Aquastat question

    Joe:

    Honeywell lists 3 separate versions of the L4081B, with a 4-digit suffix of either 1013, 1047 or 1096 & advise using the boiler installation manual to determine the specific settings----do you have a copy of the manual???

    To clarify, you have a Burnham KV84 hot water boiler (not steam); does your boiler have a "tankless coil" inside for the domestic hot water (tap water for showers/washing), or is there a separate hot water heater next to the boiler??

    To also clarify, are you saying the problem is the boiler is rapidly cycling on & off every 10 minutes----4 minutes on and approx 6 minutes off & it keeps doing this???

    Does it respond normally when you call for heat by turning up the t-stat in the living quarters???
    Last edited by Dobbs; 11-17-2011 at 09:00 AM.

  7. #7
    Join Date
    Apr 2011
    Posts
    13

    Default Re: Aquastat question

    dobbs
    Thanks for the response...
    I sent a reply but this site went down si I'll try again maybe in segments so I don't have to start over !


    I do have a coil in the boiler for domestic h.w.

    I cant find a suffix you mentioned
    the inside of the cover has the following informatiom:
    hi limit lo limit circulator
    volts ac 120 240 120 240
    full load 8.0 5.1 8.0 5.1
    locked rotor 48.0 30.6 48.0 30.6
    ign. trans. 360 va

  8. #8
    Join Date
    Apr 2011
    Posts
    13

    Default Re: Aquastat question

    As you stated...yes this is going on and off 6/4 minutes short cycles.
    Also with the domestic hot water off as well as the heat it still is going on and off.


    thanks

  9. #9
    Join Date
    Apr 2011
    Posts
    13

    Default Re: Aquastat question

    johnjh20

    I set it to 200 as the high limit and still no resolution.

    joe

  10. #10
    Join Date
    Feb 2008
    Posts
    200

    Default Re: Aquastat question

    Joe:

    I think John was referring to the DIFFERENTIAL knob inside the aquastat---from your latest post, it sounds like you adjusted the LOW LIMIT knob.

    According to my diagram/photo of the L4081B, the lower left knob near the bottom of the aquastat is the HIGH LIMIT; this should be set at 180 degrees; the lower right knob near the bottom of the aquastat is the LOW LIMIT knob; this should be set to approx 140; the knob near the top of the aquastat is the LOW LIMIT/CIRCULATOR/DIFFERENTIAL knob----I would try John's suggestion and try it at the different settings, which are 10, 15, 20, & 25 degrees.

    If nothing works, we'll look for other options & I'll send you a PM by tomorrow on other things to try.


    Dobbs

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