The days of Monkey Boy Service Calls are over...

Click here to check out our fun short course and learn how to get the most out of Appliantology.

FAQs | Repair Videos | Academy | Newsletter | Podcast | Contact

Stay connected with us...

Samurai on Facebook - become a fan today! Sign up for our free newsletter and keep up with all things Appliantology. Subscribe to our YouTube channel for lots of appliance repair tips and help! Follow the Samurai on Twitter and get timely morsels of Appliantological Wisdom! Subscribe to our MST Radio podcast to learn secrets of the trade.
  • Announcements

    • Samurai Appliance Repair Man

      Webinar Recordings Index Page   10/03/2017

      On-demand appliance repair training videos for Professional Appliantologist members Over 30 hours (and growing!) of original, high quality appliance training webinars developed and given by yours truly are at your fingertips, on topics you won't find anywhere else. Fill in those knowledge gaps, strengthen those areas of uncertainty, and boost your skills. Watch on mobile or desktop at your convenience whenever, wherever.  Ultra Short Primer on Basic Electricity, Circuits, Ohm's Law, and Schematic Reading (Length: 1:04:48) Basic Refrigerator Troubleshooting (Length: 1:10:45) Schematic Reading Workshop, 10/2015 (Length 1:19:08) Troubleshooting Strategies for Computer-Controlled Appliances (Length: 48:34) Semiconductors and PN Junctions (Length: 1:04:37) Appliance Temperature Sensing Devices & Technology (Length: 1:27:33) Voltage Measurements, Meters, Ghost Voltages, and Triac-controlled Neutrals (Length: 1:29:32) Troubleshooting with Tech Sheets, Part 1, 4/2016 (Length: 1:09:26) Troubleshooting with Tech Sheets, Part 2, 4/2016 (Length: 1:21:11) Tech Sheet Review, 4/9/2016: Bosch Speed Cooker, Amana Refrigerator, GE Glass Cooktop Range (Length: 1:22:58) Pulse Width Modulated (PWM) Switches used in Samsung Switched Mode Power Supplies (SMPS) (Length: 27:07) PWM Computer Cooling Fan in a Whirlpool Refrigerator (Length: 14:53) Understanding AC Split-phase Household Power Supplies (Length: 52:41) Troubleshooting a Samsung Electric Dryer without Disassembly using Live Tests and the Schematic (Length: 22:47) Troubleshooting a Bosch Dishwasher No-Heat Problem using the Schematic and Live Tests (Length: 15:38) Linear Motors and Linear Compressors (Length: 55:54) Bi-directional PSC Drive Motor Systems in Whirlpool VM Washers (Length: 56:52) Appliance Service Call Structure and Troubleshooting Strategies (Length: 1:00:16) The Ten Step Troubleshooting Tango and Workshop Exercises (Length: 1:35:39) Troubleshooting Ten-Step Tango Advanced Workshop (Length: 1:32:06) Ten-Step Tango Troubleshooting Workshop: Refrigerators (Length: 1:35:57) Whirlpool Duet Washer Schematic Analysis & Whirlpool Dryer Moisture Sensor System (Length: 1:03:04) Neutral Vs. Ground, Inverter Microwave, Digital Communications, Loading Down in DC loads, and more! (Length: 1:14:45) Gas Oven Service Call After a Parts Changing Monkey (Length: 36:04) AFCI and GFCI Circuit Protection Technology (Length: 41:26) Troubleshooting Samsung Refrigerators and more (Length: 1:29:58) 3-way Valves and Dual Evaporator Refrigerators (Length: 1:15:45) Split-Phase Compressors and PTC Start Devices (Length: 1:11:57) Gas Dryer Ignition Systems (Length: 53:50) Refrigerator Sealed System Thermodynamics, Part 1 (Length: 43:07) Refrigerator Sealed System Thermodynamics, Part 2 (Length 1:09:09) To access these webinars and all the other info-goodies here at Appliantology, become a Professional Appliantologist today. If you need cost-effective, time-flexible, state-of-the-art appliance technical training, check out the Master Samurai Tech Academy.
    • Samurai Appliance Repair Man

      [Webinar] Practical Refrigeration Sealed System Thermodynamics - 10/30/2017 @7PM ET   10/19/2017

      Having laid some theoretical groundwork in the last webinar, we're going to focus on practical considerations in this one. Here are the topics we're going to discuss: Review homework from the first session on 10-2-2017. Home refrigerator practical design and operating rules-of-thumb useful for troubleshooting Practical application exercises Troubleshooting scenario exercise Techniques for making system temperature measurements for determining superheat and subcooling Sealed system diagnosis homework assignment (to be reviewed in the next webinar in this series) See this calendar event for more details                   
Budget Appliance Repair

Help with Flame Rectification specs on Coleman/Evcon DLAS056BDC furnace

Recommended Posts

Budget Appliance Repair

Coleman/Evcon forced-air furnace

Mod# DLAS056BDC

Ser# 941258626

Problem was flame wouldn't light, replaced bad ignitor and found another problem.

Original ignition control module: RobertShaw HS780/34NR-306A

1) Draft Inducer comes on

2) 34 sec ignitor warm-up

3) Gas valve receives 24 VAC and flame ignites

4) 6 second ignition proof starts

PROBLEM:

5) flame goes out, it doesn't see the flame

Cleaned flame sensor rod and burner, checked all wiring polarity - all OK

I have never taken the Micro-Amp readings from a flame sensor before so have no idea what range they should be in so did a bunch of research online and found good info on how to do and found that my meter is able to read Micro-Amps.

Found the attached PDF file online that explained what I need to know and gave some general specs.

If I check voltage on the flame sensor I get a good solid 119 Volts from flame sense terminal to ground and when checking for uA DC I get a good reading of 3.0 - 3.2uA DC -- I can't find any info on the RobertShaw controls as to what range of uA DC the flame sense circuit is looking for.

The general info I have found says these controls can run anything from .10 uA - 10 uA

I did find on one spec sheet for a RobertShaw control similar but not the exact same part of 1.5 uA which the 3.0 uA that I'm getting is well within the limits.

From everything I've done, (including running a ground wire directly from the module to the burner assembly), I conclude that the ignition modules flame sense circuit has failed and plan on replacing it with a S8910U1000 Honeywell ignition control module.

Would all the above sound like the ignition module is definitely my problem and does anyone have the actual specs of what the original control module uA DC reading should be.

Thanks for any help you can provide,

Flame Rectification Info.pdf

  • Like 1

Share this post


Link to post
Share on other sites

Need appliance parts? Call 877-803-7957 now!

applianceman18007260692

My friend a tv repairman that works at the wings of life as a volunteer told me he removed the cover on these modules and has had quite a bit of sucess in soldering a loose connection on the pilot flame sensor ground terminal. The solder connection comes loose. Remove that cover on this puppy and look for a loose solder connection:

post-2707-0-43180500-1325526389_thumb.jp

Edited by applianceman18007260692
  • Like 3

Share this post


Link to post
Share on other sites
Budget Appliance Repair

I don't know why I didn't think to open the box and look for anything obvious like burnt solder connections, (I usally do that on range and other controler boards).

I've ordered the new ignition module and will install it but will take the old one apart and see what I find.

  • Like 2

Share this post


Link to post
Share on other sites
Shootist

Don't forget to check/clean the flame sensor and make sure the furnace is properly grounded.

  • Like 2

Share this post


Link to post
Share on other sites
Budget Appliance Repair

Thanks Shootist, check/clean the flame sensor was my first action to correct, it didn't change anything.

On a follow-up visit after some research on how to check the uA DC current of the flame sensor I also cleaned the burner itself and checked all grounding. All grounding is OK and the cleaning of the burner nozzle didn't change anything, (I had never had to or thought of the burner itself needing to be cleaned but it makes sense because that is the path of ground through the flame and to the burner as ground).

The new ignition module should be arriving on Friday so will know soon enough if that is my problem.

Edited by Budget Appliance Repair

Share this post


Link to post
Share on other sites
Budget Appliance Repair

Installed new Honeywell S8910U1000 ignition module and all works well. Took the old module apart and no loose/cold solder connections, nothing obvious that was causing problem so must be in the flame sense circuitry.

Just for my knowledge I took the microamp reading of the flame sensor on the new module and it never showed a steady reading, (it kept jumping around from a low of .9 uA to 4.2 uA, generally staying in the 2 - 3 uA range but never a steady constant reading).

The old module that wasn't working showed a good constand 3 - 3.2 uA thru the complete six seconds of flame proof.

Can anyone tell me if an unstable reading is normal, (caused by the movement of the flame changing the characteristics of the flame envelope that the sensor is imersed in)?

  • Like 1

Share this post


Link to post
Share on other sites
RegUS_PatOff

sorry, I don't know,

but, are there any uA readings with either Module when there is no Flame ?

Share this post


Link to post
Share on other sites
Budget Appliance Repair

The original bad module showed a solid and steady 0.00 uA when no flame was present.

The new module went into a negitive reading of around - 0.9 uA when no flame was present and module was energized going thru prepurge and ignitor warm-up.

Share this post


Link to post
Share on other sites
RegUS_PatOff

Flame Rectification

some info:

... The Controller sends about 90v AC to the Flame Sensor .. check with the Controller mfg.

As for flame rod position, keep in mindit is not a thermocouple. Heat does not generate voltage for the signal.

If the flame rod is too close to the ground within the cone of the flame, you will actually get a weaker signal.

To set up the strongest potential, you actually want the flame rod out on the edge of the main flame cone

where the most positive ions are, teasing them into lining up so the signal can hop-scotch across to the ground.

Too close and it doesn't seem to draw in enough ions for stepping stones.

When cleaning the flame rod, don't forget the ground connections.

Another thing to watch out for is the position of the sensor in the flame.

I know of some techs who will bend the sensor to get a higher reading rather than clean the crossovers on the burners or the burner itself.

When I find a bent one I usually replace it and start from square one.

Knowing the history of past service calls sometimes reveals the need for a sensor or hsi replacement.

Carefull, if you find a bent flame sensor on a Lennox 80MGF or G24 furnace,

someone probably bent it as called for in a service bulletin.

Lennox had some problems with their choice of flame sensor position on those furnaces about 10 years ago.

Per Honeywell and others, there is a correct ratio of areas exposed to the flame.

The ratio is 5:1. That is, the area of burner or pilot hood (etc) should be 5 time that of the rod.

Therefore proper flame rod orientation is extremely important.

Early in the residential sector flame rods were often misaligned.

Now days a technician really has to work hard at incorrectly installing a flame sensor.

Most all are indexed by a tab or slot that correctly aligns the rod.

One thought on cleaning the rod, do not use anything that will leave groves on the rod.

These groves will only increase the rate of fouling the sensor rod.

For this reason sand cloth, emory cloth, and some steel wools are not reccomended.

http://www.amgair.co...on/Flamerec.pdf

http://www.amgair.co...ication0001.PDF

http://www.achrnews....fication-system

http://www.achrnews....on-service-tips

http://www.fieldpiec...e-rectification

http://www.ien.com/a...tification/7534

  • Like 1

Share this post


Link to post
Share on other sites
Budget Appliance Repair

This is something I wasn't sure about and have some questions regarding

.. The Controller sends about 90v AC to the Flame Sensor .. check with the Controller mfg.

And specifically this complete step:

Make sure there is AC voltage between the flame diode and the base of the flame. Measure AC voltage from the flame sensing rod to the base of the flame. The value varies by model (in neighborhood of 90V), but the important thing is to ensure that there is voltage present. If there is no voltage, check to see that the wires from the module to the flame sensing rod are correctly connected or if the flame sensing rod or the wire connected to it is grounded.

I measured from the sensor terminal on the ignition module to the ground of the furnace and got a reading of the full 119 VAC.

From the diagnostic statement above it sounds like you should actually be taking the voltage reading from the end of the flame sensor rod to the base of the flame, (meter probe tip in flame, NOT to the actual burner head itself)? Is this how you would read it to mean?

If that is the case, then no way to really test this Coleman unit in that manner since the burner is inside a sealed chamber with just a little 1" site glass window to see the burner and ignitor operation.

  • Like 2

Share this post


Link to post
Share on other sites
Daveb1972

I know the manufacturers say not to clean the rod with abrasives, BUT I'm sorry to say if you don't, they don't get clean. There is enough junk in the natural gas that coats that flame rod (sulfates, and hi temp leas to oxidation) that the rod becomes an insulator. Cleaning the flame sensor rod is part of normal maintenance, and often the source of midnight no heat calls (I work as the on-call tech for a local HVAC company). There isn't any magic in the rod, just a probe that uses the flame to act as a diode and conduct to ground. When the reading is stable and the rod has been cleaned with emery cloth, AND it wont hold flame, replace the module. Don't try to test HSI's for flame rectification (some modules will let you use the HSI as the flame rod) because you'll cook your meter. Newer Lennox units will give erroneous readings if you try to take flame sense readings directly (units made after 2010 with the 8 segment LED display on the board)

For your own checks, test flame sensor current before cleaning, then after. You'll easily see the benefit to cleaning the rod. The rod is mostly stainless steel, which isn't really stainless at high temp. The oxide layer that forms has to be broken mechanically,(with abrasive) but not aggressively. (My day job is in stress corrosion cracking of nuclear grade stainless steels, in high temps and in aqueous environments)

  • Like 2

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now