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Hot surface vs intermittent pilot?

ChrisJ
ChrisJ Member Posts: 11,974
I've seen these systems mentioned many times and I've always wondered why do both exist?

I'm assuming there are pros and cons to both? What are they?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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Comments

  • Larry_52
    Larry_52 Member Posts: 181
    edited March 2015
    Chris do you mean direct spark? Intermittent pilots are rarer these days and have more working parts than a HSI. So versus the intermittent pilot my vote is for HSI. If it where a HSI versus direct spark its a tough call with many opinions.

    As for why one over another, could only guess. Space, noise, current demands on controllers, feedback, type fuel, etc probably influence the outcomes.
  • ChrisJ
    ChrisJ Member Posts: 11,974
    Larry,

    I've only worked on my WM which is an intermittent pilot. I think my Bradford White power vent heater is also intermittent pilot?

    Didn't know direct spark existed, though I thought intermittent pilot seemed kinda funny but I assumed it exists because no one trusts a spark to light the main burner.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Empire_2
    Empire_2 Member Posts: 2,343
    Do you mean HSI vs spark ignition? If we're talking pilot ignition, I guess it's all what the MFG sides with for one reason or another. If you are talking "Direct fired" ignition where the main valve ignites the main burner, then with units that are indirect fired I see both, but direct fired units like MUA equipment where air is pulled through burner manifold directly into building generally spark is used basically due to the HSI not being able to survive the moisture in the air which can crack the element. It may have to do with what ignition modules they use, cost, application. I'm sure others will chime in.



    Peace;
    MPT...
  • ChrisJ
    ChrisJ Member Posts: 11,974
    Empire said:

    Do you mean HSI vs spark ignition? If we're talking pilot ignition, I guess it's all what the MFG sides with for one reason or another. If you are talking "Direct fired" ignition where the main valve ignites the main burner, then with units that are indirect fired I see both, but direct fired units like MUA equipment where air is pulled through burner manifold directly into building generally spark is used basically due to the HSI not being able to survive the moisture in the air which can crack the element. It may have to do with what ignition modules they use, cost, application. I'm sure others will chime in.



    Peace;
    MPT...

    I'm talking more about atmospheric type units, but honestly am curious about all types.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Larry_52
    Larry_52 Member Posts: 181
    edited March 2015
    Direct spark just uses some feedback for flame, typical for oil with photo cell and same for most gas power conversion burners. Residential atmospheric air/gas, all I have ever seen is spark pilot with thermocouple feedback or HSI.

    On industrial for gas direct spark to gas igniter is typical with thermocouple or photocell feedback. we are mandated to use igniters, no more oil soaked rags, lighting off adjacent burners and finally for the real cowboy lighting off the brickwork.

    I imagine the whole direct spark to atmosphere air/gas is prohibited in residential as the non power burner residential system has no built in way of knowing it is actually sparking and does not purge.

    So a failed igntion on atmosphere air/gas for a second and dump of gas would lead to some interesting issues.

    Again just on parts the HSI can be less trouble free than intermittent pilot in my own experience.
  • ChrisJ
    ChrisJ Member Posts: 11,974
    This is the setup that is on mine.

    My assumption is one probe sparks, and the other somehow much measure a resistance difference when a flame is present. Honestly, I have no clue though other than it's only got two wires.


    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Larry_52
    Larry_52 Member Posts: 181
    Right "more trouble free"
  • Larry_52
    Larry_52 Member Posts: 181
    edited March 2015
    High voltage wire to electrode jumps to ground for spark. The other wire is feedback from thermocouple which is two dissimilar metals joined together so when heated produce a small voltage potential hence feedback. Thermocouples can be used for feedback, high temp readings, or power source.

    The only failures I ever see on them is the spark circuit board, high voltage xfmr or bad thermocouple. HSI you basically can fail the controller or the hot surface silicon carbide or nitride. The carbide being what failed more and the newest hsi's are silicon nitride which last longer. They are really delicate but once installed pretty foolproof. If they get dirt or moisture on them this will create thermal differential with them and fail.

    Probably why your burner rack is intermittent versus HSI. the HSI element is too exposed in this array between dirty air and a leaking boiler.
  • ChrisJ
    ChrisJ Member Posts: 11,974
    Interesting.

    So in my case, the further larger one is actually a thermal couple? So the only ground both the spark and very sensitive thermal couple have is either through the pilot tubing, or the somewhat crummy couple of the burner tray to the block!?

    That seems like asking for problems, no?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 11,974

    I was always impressed with the intermittent pilot. Generates a high voltage spark from 24V and minimal current...........sufficient to light the pilot.

    My Weber Grill uses a single aaa battery that lasts years, literally. :)
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 11,974
    edited March 2015

    ChrisJ said:

    Interesting.

    So in my case, the further larger one is actually a thermal couple? So the only ground both the spark and very sensitive thermal couple have is either through the pilot tubing, or the somewhat crummy couple of the burner tray to the block!?

    That seems like asking for problems, no?

    I believe the control has a ground wire to the gas valve. The gas valve and the burner tray are common to each other.
    No,
    No ground wire, though it is connected via black iron pipe.

    And I just realized that's basically what you just said. Sorry for the confusion.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Larry_52
    Larry_52 Member Posts: 181
    ChrisJ said:

    Interesting.

    So in my case, the further larger one is actually a thermal couple? So the only ground both the spark and very sensitive thermal couple have is either through the pilot tubing, or the somewhat crummy couple of the burner tray to the block!?

    That seems like asking for problems, no?

    The one in the flame is the thermocouple and the big one is the electrode.

    Thermocouples are pretty trick when stacked in series like a powerpile or the curiosity Mars rover using a nuclear reactor to heat them. Curiosity's power supply would make the energizer bunny jealous.
  • Larry_52
    Larry_52 Member Posts: 181
    ChrisJ said:

    I was always impressed with the intermittent pilot. Generates a high voltage spark from 24V and minimal current...........sufficient to light the pilot.

    My Weber Grill uses a single aaa battery that lasts years, literally. :)
    And funny here you see an outdoor appliance that allows direct spark to gas without feedback. Only feedback for flame is that little hole you have to bend down to look at and burn your face if you left the gas on for to long.
  • Empire_2
    Empire_2 Member Posts: 2,343
    In your particular set up, spark is provided by the rod closest to the pilot hood. The other rod is your flame sensor. Pilot is proved thru DC Flame rectification. The ignition module provides a small amount of current through the wire, to the rod, then the flame itself completes the circuit to ground thus providing a complete circuit in UA or micro amps that prove the pilot is sufficient and then allows the main valve to energize. Any interruption in the circuit to ground through the pilot flame will kill the entire main valve circuit. Your chasses is ground and that is OK provided the ground wire from the electrical panel is brought to the furnace. This is why in MFG literature it is important to mechanically ground the equipment.


    MPT...
    AlCorelliNY
  • Abracadabra
    Abracadabra Member Posts: 1,948
    ChrisJ said:

    Interesting.

    So in my case, the further larger one is actually a thermal couple? So the only ground both the spark and very sensitive thermal couple have is either through the pilot tubing, or the somewhat crummy couple of the burner tray to the block!?

    That seems like asking for problems, no?

    No.. the further one is the flame sensor, not a thermocouple. When a flame is present and impinges on the flame sensor a circuit is completed. The flame itself is part of the electrical circuit. When current flows from the flame sensor rod to the pilot assembly thru the pilot flame the control knows there's a pilot flame present. Something like 5-10mA will flow and the control senses this and allows the main gas valve to open. If there's no pilot flame the circuit from pilot assembly to flame sensor is not completed, it's open and control knows there's no flame. Think of the pilot flame as a resistor or piece of wire completing the circuit.
    AlCorelliNY
  • Empire_2
    Empire_2 Member Posts: 2,343
    Just so we're clear.....No T-Couple here.
    AlCorelliNY
  • unclejohn
    unclejohn Member Posts: 1,749
    That is not a thermocouple. That is a flame sensor and Tim can explain how they work. Here is kinda how it works. If a flame is present a current is sent to ground through the flame and the gas valve opens. No flame, no signal, no main gas valve.
  • ChrisJ
    ChrisJ Member Posts: 11,974

    ChrisJ said:

    Interesting.

    So in my case, the further larger one is actually a thermal couple? So the only ground both the spark and very sensitive thermal couple have is either through the pilot tubing, or the somewhat crummy couple of the burner tray to the block!?

    That seems like asking for problems, no?

    No.. the further one is the flame sensor, not a thermocouple. When a flame is present and impinges on the flame sensor a circuit is completed. The flame itself is part of the electrical circuit. When current flows from the flame sensor rod to the pilot assembly thru the pilot flame the control knows there's a pilot flame present. Something like 5-10mA will flow and the control senses this and allows the main gas valve to open. If there's no pilot flame the circuit from pilot assembly to flame sensor is not completed, it's open and control knows there's no flame. Think of the pilot flame as a resistor or piece of wire completing the circuit.

    So my original assumption was correct, it senses the resistance of the flame, so to speak. Or, lack of vs air.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Empire_2
    Empire_2 Member Posts: 2,343
    No Chris. Read comment above. resistance is not the way this sensor and ign. control mod works.


    MPT...
  • JUGHNE
    JUGHNE Member Posts: 8,948
    edited March 2015
    Empire, you stole my thunder on this one. Is there any T-couple system with a spark or HSI? The way I understand flame rectification is that the module or controller sends out an AC voltage and it is rectified into DC by the presence of flame; the current has to pass thru the flame for this to take place. No fire...no gas; not fooled by anything but fire.

    As for any electrical circuit there has to be 2 conductors; one would the spark cable and the other the ground path/wire. Making the grounding very important for proving flame. Or it is the flame senor and the ground path/wire.

    We like HSI today, but when first introduced in the late 70's or early 80's there were a lot of call backs. The HSI would fail, Rheem/Rhuud suppliers would just give you a stock of Norton HSI for replacements. Originally they tried using the HSI as the flame sensor. Soon there were free retrofit flame sensor kits available. So you had call backs and then had to add a kit....all on your new furnace. Just bouncing the furnace around could damage the HSI. It was recommended to remove the HSI before taking down stairs and installation and install after all work was done. Suppliers were sure that next generation that all ignition systems would be spark. So here we are now. I'm amazed how old the HSI get sitting on my shelf.

    Edit: just to stress that flame rectification has to take place. AC changing to DC by passing thru the flame. You cannot complete the circuit by shorting the sensor to ground. You need fire.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 11,974
    So,

    The flame not only completes the circuit, but also must act as a rectifier?

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Empire_2
    Empire_2 Member Posts: 2,343
    Oh...I agree the cracks seem to happen if you looked at it the wrong way...lol DC flame rect. works by or when the ignition module sends out a DC signal measured in micro amps. As we know DC circuits are used with a ground (in this case the frame is ground because the building is grounded) and the DC voltage created by the module is a part of a circuit which needs to energize the main valve. Once the flame if proper allows the dc signal to pass to ground via the flame, this is what completes the circuit inside the module to allow main valve to come on. Typically it is measured in UA, micro amps or Mili-amps. Depends on module. I will often times add a ground wire directly to burner frame, or pilot burner itself. The idea is to have as good of ground as possible.


    Mike T.
    ChrisJ
  • Empire_2
    Empire_2 Member Posts: 2,343
    T couple with HSI or spark, generally no because the t-couple works off mili volts which is a different type of proving flame, generally in a standing pilot application.


    Mike T.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    ChrisJ said:

    So,

    The flame not only completes the circuit, but also must act as a rectifier?

    Yes.. I said resistor... I meant diode. Current is allowed to flow in only one direction.

    ChrisJ
  • JUGHNE
    JUGHNE Member Posts: 8,948
    edited March 2015
    The module is looking for the AC it sends out to come back as DC. ( a changed man you might say). Then it knows that flame is proved and may open the main gas valve or keep it open. When it loses the DC signal, It assumes no flame and gas is shut off; much quicker than any T-couple would do. Just a couple of seconds versus 30 to 50 seconds for T-couple.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 11,974
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Empire_2
    Empire_2 Member Posts: 2,343
    edited March 2015
    Close Jughne,..... The AC is in the rectification inside the module, but the signal itself is DC. You can measure this and if you meter leads are set for AC it will be an incorrect number and also if your leads are connected incorrectly + and - your number in UA will be also incorrect. + from the meter connects to the wire coming out of the module and the comm on you meter will connect to the flame rod via a jumper to the rod. This will give you your UA reading.


    Mike T.
  • ChrisJ
    ChrisJ Member Posts: 11,974
    That would suggest it could easily be fooled with a resistor of the right value. Or leakage to ground via damp dust ? The wiki page states this is why flame rectification is used?


    Now I'm confused
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 11,974
    edited March 2015
    I suppose if I think of it and have time I can hook a scope probe to mine and see.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 8,948
    edited March 2015
    Chris J's Wikipedia definition above implies that the ac must travel thru the flame to become DC. Yes, we measure DC micro amps returning to the control device to see how good the pilot or main burner flame is to maintain gas flow.

    Maybe Tim will give us answers tomorrow.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Yea, I guess that's a good idea. Anyway, I personally could care less. Measurement is what I am after and really don't need that defined although it would be good to know for sure. Just like a resistor in a circuit board, If it does not put out what it is supposed to, Replace the board..
  • Empire_2
    Empire_2 Member Posts: 2,343
    Definition of rectifiers... Rectifiers are electronic valves which permit the flow of current through them in 1 direction ONLY. These devices change alternating current to an output of direct current. As I stated before, "A simple rectifier uses only 1 half of the sign wave. To use both halves of the sign wave and still produce only direct current, one must use four diodes (which is inside of the ignition module). DC current is measured as an out put not alternating current. SCR silicon controlled rectifiers are used in applications where relays were formally used.



    Peace;

    Mike T.
  • JUGHNE
    JUGHNE Member Posts: 8,948
    I was hoping Tim would come on line and get us all straighten out on the subject.
  • Larry_52
    Larry_52 Member Posts: 181
    Feel like a bit of an A$% on the previous post. Always just assumed they were thermocouples. After reading, the timing of a thermocouple for this would be inappropriate for instant feedback.

    As per the attachment from Robertshaw the flame is rectifier.

    SCR's or aka thyristors are gated diodes that are incorporated in many power devices such as VFD's, UPS's. They are usually incorporated together and called Controlled bridge rectification.

    For a simple DC requirements a full wave bridge rectifier is incorporated which does not use gated diodes.

    Either way looks like the flame is doing the conversion not the controller.
    ChrisJ
  • JUGHNE
    JUGHNE Member Posts: 8,948
    Larry, that was a good pdf fm RS. Simplest explanation I come across so far. We are all here to learn more. I would guess there are more a few not clear on this subject.
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    I am going to chime in on this discussion when I have time. I am in the middle of two problems:

    1. Fire at my printers who does all my manuals and I have a class Monday through Friday next week.
    2. The roof at my training center is leaking all over my equipment and materials I use for training.
  • BobC
    BobC Member Posts: 5,228
    Tim,

    Ice dams have been a problem all over the northeast. I spent 5 hours on a ladder a few days after the last big storm dragging snow off my roof with a rake and chipping 5-8" thick ice dams. i was able to do it from a 16 ft ladder, I'm too old to even think about getting on the roof.

    That was enough to limit the interior leaks to two minor drips that can be fixed with a little paint come the spring.

    If your center has a flat roof I would get someone to remove as much snow as possible. One trick with ice dams is to fill panty hose with ice melt and drape it across the ice dams to cut a channel for the water to drain off the roof. I've used that trick on my front roof and it works.

    good luck,

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • JUGHNE
    JUGHNE Member Posts: 8,948
    Tim, take care of your own problems first for sure. This posting has made me open books and read, searching for answers (do I really understand this correctly??). No one has a "no heat" call connected with this conservation. Reply at your convenience when possible.
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    edited March 2015
    I've seen these systems mentioned many times and I've always wondered why do both exist?

    I'm assuming there are pros and cons to both? What are they?

    Let me try to answer the original question and then I will re read the entire posting and answer any concerns others may have or lack of knowledge.

    It did not start with this but it puts some perspective on things to address what the politicians decided.

    Intermittent pilot controls are the result of a 1987 National Appliance Energy Conservation Act (NAECA), which mandated certain efficiencies for equipment. The efficiency required for Steam Boilers 75% for Forced Hot Water Boilers 80% and Forced Warm Air Furnaces 78%. This act was effective 1992. This resulted in the present day Intermittent Pilot Systems. The system shuts down the pilot when the call for heat ends and a spark will energize the pilot and then prove the flame through rectification and safely bring the burner on.

    Most systems I first came across back in the 1950's consisted of standing pilots (burn 24/7) using either a thermocouple, bi-metal or mercury sensor to prove the flame. These relied on the temperature of the flame to in the case of the thermocouple create a difference in temperature between the hot junction and the cold junction which created a small millivoltage (25 to 30 millivolts) the mercury pilot had to get the sensing tube to 400 degrees or more to boil the mercury in the sensor which typically pressured a disc which in turn activated a switch tied into the 24 volt system for the heater, Bi-metal worked on the principle of the difference in coefficient of expansion of two different metals causing them when bonded together to warp in a certain direction activating a switch tied into the 24 volt system. All of these pilots used gas 24/7.

    The desire to be more efficient started back in the 70's especially when in 1979 it was mandated that all heating gas valves be redundant valves (dual seated). This allowed for one of the valves to become the pilot valve so that on a call for heat an electronic control (module) would send out an AC signal usually 170 to 200 volts AC. In the case of Honeywell there was out of phase with that 200 Volt AC a 20,000 volt spark signal to a single rod pilot which was for the spark. The spark would light the pilot and the AC signal passing through the soft blue properly adjusted gas pilot would be rectified by the flame changing the 200 Volt AC signal into a DC signal measured in microamps usually between 2 to 10. This allowed the pilot to be intermittent and thus save energy by not running the pilot 24/7. Single rod (direct sense) pilots are proprietory to Honeywell everyone else uses dual rod pilots (remote sense).

    The difference between Intermittent Pilot and direct spark ignition is that DSI has no pilot it lights the burner directly with a seperate spark rod and then senses the flame (microamps) with a separate flame sensor (flame rod). A large majority of Mod/Con boilers are direct spark ignition along with most conversion burners.

    Enough for now I will talk about how microamps are created and also how Hot Surface Ignition came to be.

    All of these came about in order to save energy and be more efficient.
    SWEIZman
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    Here is some more:

    Hot Surface Ignition

    This was the next step after Intermittent Pilot in creating heating equipment with no standing pilot.

    The igniter is made of a silicon carbide material, which has a high resistance when cold.

    Intermittent Pilot was a very easy conversion for equipment manufacturers; Hot Surface Ignition was a little bigger change.

    Major benefit for manufacturers is initial cost as HSI is a relatively simple control system. No pilot burner is needed and the electronics is simpler.

    There are also some limitations such as there is a very short trial for ignition period. There is also the possibility that the system may not light on every try, this leads to nuisance shutdowns.

    The igniters are also very fragile which means they must be handled very carefully. The myth that your hands can’t touch the igniter is false other than being fragile there is nothing wrong with touching with your hands. Breakage leads to service calls, which means replacing the igniter either as a charge to the customer or under warranty to the manufacturer.

    The main benefit of HSI is a lot of energy is available to light the gas. The area of coverage for ignition is almost double that of a pilot. The amount of energy expended is about the same as a pilot. It is not however on for very long. This makes the igniter application friendly for the manufacturer because with that much energy, the gas will always light.

    The electronics is simple because no spark generator is needed. A relay in the control turns the line voltage to the igniter off and on. The system uses Flame Rectification as a flame detection method just like was used on intermittent pilot.

    There are two ways you will see HSI used, one is with individual components in this case all the controls are independent of one another then a module will power the igniter and then prove the flame. This also allows for conventional wiring and control operation.

    The other way HSI is used is with either Integrated Furnace or Boiler controls. Many systems use integrated controls, which incorporate many of the individual component functions into one electronic package. The inputs required for operation are fed into the integrated control and out of the control comes power for the igniter, system blower or circulator, the induced draft blower and also incorporates diagnostics of some kind. The easiest way to picture an integrated control is that all the functions of a module are incorporated into the control along with other relate functions of the system.

    Sequence of Operation

    The system may or may not have prepurge, if there is prepurge it typically is 30 seconds. The igniter warm up time is either 17 or 34 seconds unless it is a White-Rodgers system, which uses 20 seconds and 40 seconds. The control of this time is actually incorporated into the control. The minimum ignition temperature is 1800 degrees (F). There is a tendency on the part of the igniter to take longer to warm up, as they get older.

    Trial period will vary with different companies; Honeywell will have 4, 6, 11 and 15 seconds. White-Rodgers 4 and 7 seconds and Robertshaw will be 4 and 8 seconds.

    The ignition will stay on into the trial period but is de-energized before the trial period ends to give the electronics time to sense the flame alone. At the end of the trial period, locks out or goes into the run cycle. The critical time is the time which is the flame proving time which is one or two seconds.

    The variations in the operating sequence must be noted for each system. The different prepurge times, warm up times and whether there is a hard lockout of soft lockout after multiple tries.


    The different igniter warm up times on Norton igniters are the Norton 271 Igniter has a warm up time of 17 seconds and the Norton 201 igniter has a 34 second warm up time. There are some others but these are the main ones you will see.

    The timing of the igniter and module should be the same. The actual control of the time is contained in the module. There are rules for operation however. They are although you could use a 34 second module to control a 17 second igniter; you couldn’t use a 17 second module to control a 34 second igniter.

    You can check igniters by taking ohm readings when the igniter is at room temperature. It is called the RTR test (Room Temperature Resistance) for the 201 igniter (34 second) 45 to 400 ohms, for the 271 igniter it is 40 to 75 ohms. Both will typically draw 4.25 to 4.75 amps when operating correctly.

    A little bit later on Silicon Nitride Igniters.


    SWEIZman