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Portable heater thermostat

Discussion in 'Troubleshooting and Repair' started by BrianL, Dec 9, 2011.

  1. BrianL

    BrianL

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    0
    Dec 9, 2011
    I have a Patton PRH11 radiant heater that is barely useable because the overheat sensor is bad and just a few minutes after turning on, it sounds a buzzer and turns off. There's a sensor in the bottom of the front below the elements, which I've tried bypassing, but then it doesn't heat at all. So I'm guessing that is also the main thermostat. But I don't understand how the same sensor can be the overheat sensor and the main thermostat. If it is, wouldn't the thermostat always turn it off before it sensed a temperature too high and sounded the buzzer? It does have an adjustable thermostat, and I have it at a normal setting (about halfway).
     
  2. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    How are you sure the sensor is bad? Doesn't make a whole lot of sense that the sensor is bad from the way you describe it. I admit though, I have never even looked at a PHR11 heater before.
     
  3. davelectronic

    davelectronic

    1,079
    12
    Dec 13, 2010
    Hi BrianL.
    Welcome to the forum.
    If the thermal overload switch is activated not long after switch on, then i would think either the switch is defective or it really is overloading from the elements, some units shut down on excessive current sense other units use thermal circuit or bi metallic switch, taking a current reading on switch on will tell you what might be going on, btw i would not bypass the thermal shut down, or you might cause a fire, the switch is there for safety, some pictures or a better idea of the unit would help. :)
     
  4. BrianL

    BrianL

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    Dec 9, 2011
    Sorry for the delay.
    Dave, here are some pics. The last one is larger. Are these the types of pics you meant? I assume you didn't mean what the heater looks like, since you could just google the model #.
    What kind of reading should I take? I can't take it with the heater on.

    I still don't understand how the sensor and thermostat could be the same, if they are.
     

    Attached Files:

  5. davelectronic

    davelectronic

    1,079
    12
    Dec 13, 2010
    Hi again, i see two wires off, blue neutral probably and a black possibly a jumper or ground wire, i see what i think is the simple bi metallic thermostat, where are the heating elements ? the safety cut out is almost always on the element mounted on or very close to them.
    Playing about with power on in there is a dodgy business if you dont know what your doing, i think its not so much power not getting through, more an over sensitive component / switch. :)
     
  6. BrianL

    BrianL

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    Dec 9, 2011
    Yes, a sensor is located at the bottom, below the coils. These pictures show both sides of a sensor (which ever one is it).

    Any wires off are ones I've removed. The blue and brown with slide on connectors go to the coils. The blue and black cut wires go to the sensor.

    Is there any one that knows how the sensors and thermostats in these hearters work?
     

    Attached Files:

  7. davelectronic

    davelectronic

    1,079
    12
    Dec 13, 2010
    Its very hard to work out whats going on, most, but not all sensors use a heat sensitive metallic strip with contacts welded on it, as the temperature rises the contacts snap open breaking the circuit, the safety cut out incorporates this and a similar arrangement for the thermostat, but the thermostat's control break of point is less than the safety cut out.

    In some units modules are incorporated, these contain the thermal switch, i dont know why you have removed wires, unless it was to gain access to the unit, unless someone else has any ideas, the only thing i can think of is the safety sensor needs looking at closer , these machines are simple mains operated heaters, ive not had chance to google the unit yet, i will see if i can find more detail on the circuit configeration and control options, i am not familiar with the model or make. :)
     
  8. davelectronic

    davelectronic

    1,079
    12
    Dec 13, 2010
    It does look like the thermal sensor could well be at fault, ive found loads of units for sale, but little if none in the way of a circuit diagram or component count and specifications, you could try this in the link below, but i would think the unit and components selection along with its design is poor. :)

    http://www.fixya.com/support/t3605238-patton_prh11_buzzer_sounds_high_after_2

    PS. on no account should you disable the sensor as this could lead to a fire if no over heat protection exists.
     
    Last edited: Dec 30, 2011
  9. BrianL

    BrianL

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    0
    Dec 9, 2011
    But if the overhead sensor is removed, the thermostat sensor should keep it from overheating, wouldn't it? And if the overheat sensor is kicking in too early, way before the thermostat shuts it off at it's normal set temp, the overheat sensor is bad.

    Or, I don't see how it would be possible for those sensors to be one and the same.

    BTW, I never leave the room when this heater is on, only using it on a tiled floor while in the shower, so there's really no way for a fire. Without a overheat sensor, the thermostat should shut it off before it got too hot. If the thermostat failed too, I'm just a few feet from it and would know if it's getting too hot.

    And yes, I removed the wires for easy access.
     
    Last edited: Jan 13, 2012
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,689
    Jan 21, 2010
    Never say never.

    Would you remove the fuses from your house because you know that nothing draws too much power?

    Replace the sensor, but don't remove it.
     
  11. BrianL

    BrianL

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    Dec 9, 2011
    ^ No because they're fuses, to my house. Nothing in common to this heater.

    It's a pain to get the sensor out. Before I go through the trouble, any idea how much they would be?

    Does no one here know how it works or are they just not willing to tell me? :)
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,689
    Jan 21, 2010
    There's not enough information to be able to tell you how it works.

    It could be a bimetal strip, or a metal capsule filled with a metal which melts at a low temperature, or something else.

    The easiest way of getting a new one is to find another heater the same as this and scavenge it.

    And you wouldn't remove the fuses to your house and replace them with nails because you know that the fuses are there to protect you and your property. The same is true of this sensor. if you replace it with a link you might (or might not) live to regret it.
     
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