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Thread: Instantaneous Gas Hot Water Heater

  1. #1
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    Default Instantaneous Gas Hot Water Heater

    Hi, I've got a Chromagen T26 Instant hot water system, running off LPG, that has developed a fault. The unit is about 12 years old, and sits in the weather on the back of my shed, and has worked faultlessly up until a few days ago.

    It has developed a fault where when the hot tap is turned on, after about 3 seconds you hear the fan come on and the heater flame light. Then about 1 second later, you hear a click (most likely gas solenoid) and the flame cuts out, with s slight puff of smoke from the exhaust vent, and one flash of the onboard LED. About 5 seconds it repeats the sequence. When the flame lights, you can feel a short burst of heated water at the hot water out pipe.

    There are a few sensors that can cause the problem:
    Water Input thermister - 10K ohm
    and Output thermister - 11K ohm
    flame detector - Open Circuit with no flame
    Flow sensor - (Ive cleaned the screen and get good water flow through the unit)
    But I don't know what the nominal measurements are supposed to be..

    Also there is an Overheat Cut off fuse, and a Hi Limit switch (appear to cut either power or ground to solenoids), but I can't get at them unless I remove the heater from the wall and dismantle it.

    Just wondering if anyone else has had a similar problem with a similar type of unit, and what the common faults are.

    Here's a link to the schematic:
    Last edited by bob_m_54; 01-05-22 at 02:01 PM.



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  • #2
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    Suggest you move this to the Electronics Thread to get more views.

    Are you getting any error codes ?

  • #3
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    As per the first post, the only "code" I get is a single flash from the on-board LED. Don't have a remote display/controller on it.

    I'm going to rip it off the wall, and give everything I can get at a clean, and see what happens.

    There is an error in my first post too. What I thought were two terminals of a flame sensor, is actually one for the sensor (flame rod), and the other is the igniter terminal. I did remove the Flame Rod, and cleaned it, but that didn't help. I suspect the problem may be due poor combustion from a dirt jet, or starving for air, causing a "no flame" type error..

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