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  • Bunn CWTF-15 water heater too slow

     ectofix updated 2 years, 11 months ago 1 Member · 8 Posts
  • guest

    June 27, 2016 at 12:00 am

    The 6+year-old Bunn Coffee maker CWTF-15 started taking a looong time to heat up the water inside, meaning if I pump or pour room-temperature water to make a pot, it would have to wait for more than a half hour to make the second one.  That started happening a few days after I made 10 pots back-to-back without any temperature issue.  I have already turned the thermostat off and then up to the highest without no effect.  Would replacing water heater element help or is it just equipment’s old age?  Thank you.

  • ectofix

    June 28, 2016 at 4:43 am

    Sounds like the tank heater element isn’t working and the brewer might just be heating the water with the tank’s “keep warm” element.  Impossible to say what’s wrong without opening it up to do some testing with a voltmeter, ammeter and ohmmeter.


      A malfunction of the tank’s main heater can be caused by:

    • faulty thermostat
    • open limit thermostat
    • open thermal fuse
    • failed heating element
    • bad wire or connection
  • abril

    June 28, 2016 at 12:56 pm

    Wow, thank you so much for all the suggestions.  I am glad I asked here!

  • ectofix

    June 28, 2016 at 5:24 pm

    Well thank you for thanking me!  That’s always welcomed feedback that I’d like to see everyone get here. 


    Hope it all works out with the brewer.

  • olivero

    June 30, 2016 at 5:38 pm

    Hey Abril,


    Could be a bunch of different things, considering it was a sudden change I would also suggest looking at the main heating element, could be as simple as a burnt off wire or needing a new element entirely. You should also be able to check the thermometer (depending on which kind it is) If you can access the wires to the heating element and by the time you get there, its not obvious why its not working, you can also ohm out the element, once again should have some resistance, should be stable. Should not be an open circuit nor 0 ohms, elements are normally between 30-70 ohms, most in the lower range of that.


    If its electric, check for ohms between the 2 wires, should be a stable number, not fluctuating all over the place or if its mechanical, see if the contacts on thermostat are closing or opening at any time, should be able to put your volt meter on it and see if it ever does anything.


    And if it is mechanical, then you can also check for the little copper tube going into the tank one way or another, coming in contact with the water. Sometimes, they develop a crack or break for some mystical reason, this pretty much renders them useless as the gas or liquid pushing the contacts closed once it heats up and expands in the copper tube, has escaped and it is now, useless. Its called Capillary tube.


    I would definetley start there as well as checking safeties, could be it overworked itself. Most thermostats will have a little red button on it that you can push and then it will “click” which means it was in fact tripped, if you don’t feel or hear anything, then its still working okay.


    Let us know how it goes, coffee machine are always fun.

  • fixbear

    August 27, 2016 at 8:42 pm

    You also may have used hard water and need to clean the heating element. Build up of calcium.

  • abril

    January 9, 2017 at 1:39 pm

    Sorry for the late reply.  I found out the thermal fuse for heating (boiling) element was out and got the part from PartsTown.  Thank you, fixbear, olivero and ectofix for help.  We also appreciate Partstown for providing the forum space.

  • ectofix

    January 9, 2017 at 5:29 pm

    Thank you for thanking us

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