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How to tell if Harman ESP probe is going bad? (on Accentra)

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by Val, Jan 9, 2013.

  1. Val

    Val New Member

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    I wrote about this before. My 2006 Accentra is reading room temperature "funny" on room temp. mode. It seems about 10 degrees off. I mean I have to set it over 80 degrees to get the room to 72. It never used to do this. Have run about 15 tons of pellets probably since I owned the stove. (I do clean the vent pipe and stove insides, too) Well, I finally took the esp probe out of the ehaust and cleaned it with a green scrubbie pad. It only had a very very thin layer of carbon on it and some ash. Well the stove still seems to do the same thing. If there is any improvement, maybe its too slight too notice. Is this probe getting old and time to replace? Also, this probe has the black wires. What the hell is the difference (other than the inside resistance , maybe? or length?) between red and black wire probes? How silly to have 2 probes that I swear look totally alike only that they have different colored wires. Also, if I buy a new probe, I should only buy a Harman part right? I see a lot of aftermarket parts now. I have no clue if these aftermarkets are just as good as Harman parts or if an aftermarket ESP probe even exists.

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  2. smwilliamson

    smwilliamson Minister of Fire

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    ESP monitors the exhaust temp. Sounds like you need a new room thermistor or....you need to place the thermistor up higher than the stove (get it off the floor) as you may be monitoring the cold air return. Add some insulation in yer house too perhaps. There are not too many aftermarket sensors our there for Harman
  3. smwilliamson

    smwilliamson Minister of Fire

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    red is digital, black is analog and they are different diameters...red it thicker
  4. rickwai

    rickwai Feeling the Heat

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    Replace room sensor probe. They r not very expensive.
  5. Lousyweather

    Lousyweather Guest

    maybe the RSP is bad, though Im not convinced. Take a temperature reading WHERE THE END OF THE PROBE IS, not just a general room temp. Someone with a DDM can also plug in and see what the probe is actually reading and act from there. Unfortunately a new probe is almost certainly less than a service call.

    Red Vs Black probe? Different animal.....the only production Harman still utilizing the black wire probe are the P38's....all the rest now come off the line as red. And now that the board has chabged on the 38's they may be red too. The probes are the same diameter as well, so, physically interchangeable. If you do change colors, make sure you also change dipswitch settings!
  6. kinsmanstoves

    kinsmanstoves Minister of Fire

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    ESP either work or they do not. If the ESP is bad you will get a 3 flash on the status light.

    Eric
  7. CelciusMaximus

    CelciusMaximus Member

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    i had some crazy issues with an accentra insert(2006 vintage) about a year ago.can't remember what the issues were ,thought it was the board or the esp.
    decided to change the esp first (process of elimination).sure enough that was the problem did not have blinking lights or loose connections.
    sometimes things are intermittent
  8. CelciusMaximus

    CelciusMaximus Member

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  9. Val

    Val New Member

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    The other thing that is happening is if I put the stove on stove temperature mode, the pellets will light up, burn for a while, but then burn down, shove will shut off and I will get a 5 blink status. Now, I am running some older pellets which maybe didnt ignite so well, but what I will do is scoop them out of the hopper and intermix what is left with fresh pellets. The thing is is that these older pellets still burn, and I will anticipate that I just might get the problem with the new pellets as well. My igniter area is clean. I get the 5 blink status after the stove has been up and running for less than an hour on stove temp mode, then the stove shuts down by itself. I can always change the room temp probe...but when troubleshooting is it always better to try to replace one part at a time and then see the result. Eric said if it is the esp probe it is 3 blinks and either good or bad, but I see a lot of posts on esp replacement. do some of these have esp repacements on 5 blink status as well. I notice that my Accentra has developed these behavior issues very slowly, perhaps over the last 2 years. Not really going bad all at once but i would rather correct things before I end up with unreliable stove behavior. None the less, room temperature off readings had still been a gradual problem for a while.
  10. Delta-T

    Delta-T Minister of Fire

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    sometimes if the ESP probe is coated in ash you'll get the 5 blinks cuz it wont see the actual temp of the exhaust in the timeframe it requires to know that it is running. Another not uncommon symptom of a bad ESP is that the stove will not completely shut down in the "off" position but will continue on its idle burn indefinitely. Always eliminate the obvious things by giving the stove a proper cleaning before assuming you gots bad parts. Stoves sometimes need a good talking to as well. They can get very big headed.
  11. Val

    Val New Member

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    one thing i was curious about is what the esp is made of. is it like the oxygen sensor in the car exhaust (before the catylitic conveter) so that it is made of a material inside that breaks down over time? Did you ever saw your old esp probe in half to see the inside? I looked up info on the temperature sensing bulb and found out that those devices are pretty common and how they are made. But what is inside of the esp probe that makes it work?
  12. Delta-T

    Delta-T Minister of Fire

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    its variable capacitance. most of the thermisters I know of work on resistence, so the Harman Esp I guess is a bit different. Inside is a couple wires, beyond that I dunno. Electronics is not one of my specialities. I have the tools to test the probe, but I don't claim to truely understand how it works.

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