Ravelli RV80 - Problem: Air Flow Meter

BrianJ Posted By BrianJ, Dec 30, 2015 at 3:18 PM

  1. BrianJ

    BrianJ
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    Dec 30, 2015
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    So I moved into a place in the middle of November that is heated by a free standing pellet stove - a Ravelli brand model RV80. Let me start by saying the stove had some issues when I moved in. The previous tenant (who I am still in contact with) said she enjoyed several years of excellent service from the pellet stove, but that recently it had begun operating strangely.

    She told me that she had been unable to elevate the heat level from 1 to any of the other settings, either by the remote control or through the control panel atop the stove (both had worked before). Furthermore, all efforts to contact the manufacturer or the retailer yielded no fruit. Now, this isn't a big deal for me, I don't mind it running on the lowest setting or taking a little while to heat up the place. It heats the place fine and I'm happy.

    Or I was.

    A couple days ago the pellet stove started beeping at me periodically and displaying a new error message:

    09 - Air Flow Meter

    Now I am straight bumpuzzled as to what this could mean. The manual I looked through had a list of error messages and (after doing some translating from Italian to English) I found that two of the errors listed referred to a broken or a dirty air intake sensor... or at least I think? It's difficult to research because it's a foreign product and what little there exists in English isn't all that helpful.

    I've cleaned it, both the stove and the air intake sensor, then disabled the air intake sensor by unplugging it from the circuit board (everything is still in place and in tact though). The stove still displays this error and will beep every 20 minutes or so about it. Meanwhile it still heats the place fine and appears to be working as well as it ever did. What's the deal here? Am I fiddling with the wrong part? Is there a different air flow meter? I theorized that the exhaust might be clogged somewhere and in need of cleaning but I'm not sure how to get the chimney apart to do that and before I started something so big I thought I would come and check here.

    Any ideas? Suggestions? Anything I can try?

    Thanks so much,
    -Brian
     
  2. Lake Girl

    Lake Girl
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    Are they referring to the vacuum switch?

    Edit: Referring to the debimeter but not sure of it's location and does not appear to be on my stove...

    This manual might be of help:
     

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  3. Lake Girl

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    Please be very cautious on messing with factory settings ... may make matters worse:( If you can find location of debimeter, cleaning may be the answer... or replacement.

    Edit: page 21 of the manual
    Your stove is forced into power level 1 due to failed communication from flow meter - either meter is no longer functioning or connections are a problem.

    There appears to be two dealers in your area of Oregon http://usa.ravelligroup.it/punti_vendita_usa

    Welcome to the forum and keep us posted.
     
  4. Pelleting In NJ

    Pelleting In NJ
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    Sep 26, 2011
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    Yes, your stove has one airflow sensor, also called the "Debimeter" in the Technical Manual. If you cleaned it, and it still does not work when reinstalled (also check the connector that goes to the control board), it sounds like you need a new airflow sensor. Check Ebay, or see if Barry, at North Forge Heating (Annville PA, (717) 867 1744) ) can get you one.

    Ravelli part number 0634654074997

    http://www.ebay.fr/itm/RAVELLI-Debimetre-support-Systeme-RDS-/311279318012http://www.ebay.com/itm/191624319814
     
  5. Pelleting In NJ

    Pelleting In NJ
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  6. BrianJ

    BrianJ
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    Dec 30, 2015
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    Super helpful remarks you guys, thank you so much. I will look into what you have brought to light and let you guys now if anything (or nothing) comes of it. :)
     
  7. Don2222

    Don2222
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    I had a stove with the same problem. The vacuum switch hose was clogged where it attached to the vacuum switch. After cleaning it the error was gone. After a while the error came back so by replacing the vacuum switch it fixed the problem.
    Just my 2 cents
     
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  8. johnnyboy61

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  9. johnnyboy61

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    where was the flow meter located? I don't see it on manual
     
  10. rich2500

    rich2500
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    It's in the fresh air intake tube, if you remove the fresh air vent from the back of the stove and look in you will see it.
     
  11. Monica in France

    Monica in France
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    I have actually purchased an airflow meter for a Ravelli RDS system : I was dreaming about converting my Monica to a more sophisticated algorithm using an Arduino to replace the actual micro-computer, and consider this sensor fundamental for better control ( especially when it is getting near a 'clean needed ' situation).
    Despite its high price , this 'airflow meter' was entirely passive: composed of two temperature sensors ( needing bridges) and a heating element. The circuitry necessary to be able to use it is apparently on the printed circuit board. When I put this project back 'in plan' I will look at the car fuel injection market instead.
    So while it is possible that this component is 'hors service' I think it unlikely. It is however easy to remove and check that it has continuity. If it is duff , it is probably the heating resistor which , by chance , is the easiest to check.
     
  12. waltonb

    waltonb
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    Mar 2, 2015
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    My Ravelli RV-80 has this exact problem. Display "09- Air flow meter" followed by 10 beeps. Stove will operate only in "Modulate" mode, which means no high RPM fan to blow the hot air around. Looking for some solution.

    There seems to be no online source in the US for the "debimeter" (air flow sensor) which is located in the air intake pipe just inside the rear panel.

    Cleaning does not make a difference... in fact it does not look the least bit dirty.

    Is there any hope that I can fix this?
     
  13. rich2500

    rich2500
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  14. johnnyboy61

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  15. johnnyboy61

    johnnyboy61
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    Thanks. Trying to get a picture of flow meter but unable to find one
     
  16. Ssyko

    Ssyko
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    Nov 6, 2017
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    debitmetre-ravelli.jpg
     
  17. johnnyboy61

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  18. johnnyboy61

    johnnyboy61
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    Thank you. Wanted to make sure I had the right piece. I did. Now just have to find one
     
  19. johnnyboy61

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  20. Ssyko

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    Google is your friend ;)
     
  21. Joe into Physics

    Joe into Physics
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    Nov 21, 2017
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    I removed the outside air supply hose and looked into the air intake of my stove and immediately spotted the two green "fingers" pictured in the message above from Ssyko. I lifted out the two panels to open up the right side of the stove (as you face its front), and there, about 8 inches in from the end of the intake pipe was the red rubber sensor body with a 4-wire electrical connector plugged into it. It was held on by two screws and three disposable tie wraps, which hold the rubber down tightly to seal the opening in the pipe. I removed the sensor and examined it, including under a low power microscope, whose magnification was necessary to read "75R0" on the heater resistor, indicating 75.0 ohms. My measurement of it came within 1% of spec. Those two green "fingers" in Ssyko's photo are indeed extensions of a circuit board reaching across the air passage. The upstream finger has a chip thermistor "RT2" which read about 11,700 ohms at 72 Fahrenheit (22 C). The downstream finger has the 75 ohm heater resistor right next to another thermistor, "RT1" which read about 13,000 ohms at the same temperature, or 11% higher than "RT2." These are probably nominally the same component, and unlike ordinary resistors, these thermistor components typically are spec'd to within 10% on either side of nominal at a reference temperature, meaning that the 11% ratio difference could be within spec. I haven't checked what voltage goes to the heater resistor when in the stove circuit. Logic circuits typically operate with a supply somewhere between 3 and 5 volts, with 3.3 being typical. Having a 5 volt supply handy, I used that for a test, which should cause 0.33 watts of heating in 75 ohms. That amount of heat, applied in still air, lowered the thermistor resistance from 11,700 ohms to 1,500 ohms in the space of 40 seconds and, with the resistance close to leveled-off, I blew a hair dryer on cool across the sensor, cooling it and raising the resistance back up to 5600 ohms. Thermistors of this type respond exponentially to temperature change, and the extreme resistance changes observed here seem totally normal in this setting. The motherboard circuit probably senses a ratio of resistances and triggers an "insufficient air flow" signal when that ratio crosses a specific threshold. Blowing air on the sensor caused a 3.7-to-1 ratio change in resistance, while operation on a 3.3v rather than 5.0v supply might drop that ratio down from 3.7 to 2.4 (assuming an exponential temperature response). That ratio range, compared to a measured 11% resistor mismatch at matching temperatures, leads me to doubt that the resistor mismatch could account for an error reading. Also, after having the stove work fine for its first year, and with no obvious sign of malfunction in the sensor, why should I think that a thermistor being out-of-spec would suddenly cause a problem? I'll report back as I learn more, but it seems to me that the sensor malfunction error message isn't there because the sensor itself is defective. That, of course, represents a "statistical sample of one," so I'd be cautious about generalizing to what normally causes this sensor error problem. Also, heating a circuit board of this size at 0.33 watts or below, in a cooling forced air stream, should not unduly stress the circuit components, so that I wouldn't expect frequent failures in this extremely simple three-component circuit.
     
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  22. bob bare

    bob bare
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    Very nicely written.For your information,older car MAF (mass air flow) sensors could throw a fault code from having a film of dirt over them,then manufacturers loosened up the error reporting,but cleaning it became part of rotine maintenance.Perhaps these stoves have an software upgrade?If monica checks this post,the old Austroflamm Integras MAF was a BMW based part.
     
  23. Joe into Physics

    Joe into Physics
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    Thanks, bob bare, for the advice regarding MAF (mass air flow) sensors. I wasn't even thinking about a film of dirt, and cleaning the sensor is an easy first step. I realize that sensors like this are "for my own protection" (the flip side of same being "protection of the manufacturer from liability when my house burns down"), but perhaps arrogantly believing that I have the skill to take control of this situation and bias the system just a tad in favor of KEEPING THE DAMN STOVE RUNNING !!! I shall make an adjustment that for me is more accessible than trying to edit the system software. I have some high-value but similar negative-TC thermistors that have sat in their drawer for about 40 years, so I don't seem desperately in need of preserving them. I think I'll try an analog tweak and solder one of them in parallel with that above-spec "RT1" component. That's probably less unwise that placing a penny behind that annoying fuse that keeps blowing. (Am I inadvertently revealing my age by referring to screw-in fuses???)
     
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  24. Ssyko

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    :cool::cool::cool: right there with ya.
     
  25. bob bare

    bob bare
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    Actually the MAF has nothing to do with protection,in your stove,my integra,or cars,it is for metering the fuel for a cleaner,more efficient burn.
     
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