Flame sensor micro amps

[wishful]

Lennox G2003E-75-2. Has spark-to-pilot module and seprate sensor rod. It has a pretty blue pilot with good impingement, I cleaned the sensor rod with a soft brass brush and clean white paper, my Fluke reads 1.4 micro amps in series with the sensor. The main valve wont kick in and the furnace goes into lockout. What micro amp reading should I be getting? (I think I have a weak module.) Thanks guys, from a 'retired' tech with a bad memory.

[tinknocker service tech]

your reading seems ok

[docholiday]

so what is the voltage from the sensor to ground?

[ej45]

Check for voltage at the main gas valve terminals or at the module output serving the gas valve. If your microamps are good your module should energize the gas valve main valve.

[Steve Wiggins]

Try reversing the polarity. Your 1.4µA reading should go up to 2.8µA

[wishful]

I'm going back tomorrow, this furnace has worked fine 'till this season. Did you mean to check the polarity of the 120vac that powers the furnace? I will do that before replacing anything, however I do need to check for 24vac at the gas valve and continuity of the main coil on that valve also. The spark that lights the pilot keeps clicking untill lockout. I do expect voltage from the sensor to ground, but then again I don't remember what that reading should be. I do remember on some HSI units that if you get 103 to 105v from the sensor to ground, then the module is bad. Is it the same for spark to pilot? Thanks again guys.

[Jultzya]

Originally posted by wishful
The spark that lights the pilot keeps clicking untill lockout.

Here's your sign! :D




I'm kidding BTW. :p

[klyons20]

make sure all you limits are good..

roll out switch, high limit, provent switch, etc, all these could hold it back. What model of controler would help.

When u get a pilot jump pv to mv. This will verify you have a good gas valve.

regadrs,
kelvin

[tinknocker service tech]

ake sure the connection for the flame senser to the control is good and tight. i have seen a lot with loose spade connections and the true signal never reaches the control. i have also seen cases where the clip that holds the senser in place is loose and the senser drops down a little and dose not get the right recifacation.
personaly i think you have a defective control. but just a guess

[MadeinUSA]

Why don’t you idiots just give your phone numbers out so you can give every homeowner in the country step by step free advice so no contractor in the country can make a living.

All you idiots are doing is building a file where every homeowner can go hit search and solve their problems here instead of calling a local contractor.

What the heck do you think the Pro technical forum is for? Did you ever possibly think it might be to discuss matters such as this?

[borgis]

Hey made in the usa good point, i hope they listen to you.

[Steve Wiggins]

Yeah I agree. By the lingo he was using he sounded competent but after reviewing his past posts I now realize he is an illegal side jobber being very selfish in taking work away from legitimate contractors. Sorry wishful, no more technical help.

[tyreman]

One must keep an open mind.
it could be an "impossible" to clean impregnated sensor rod even another malady of same.
OR could be 'nother issue entirely.

[t527ed]

early model g20 has the blues prolem

[Milk man]

Originally posted by madeinusa
Why don’t you idiots just give your phone numbers out so you can give every homeowner in the country step by step free advice so no contractor in the country can make a living.

All you idiots are doing is building a file where every homeowner can go hit search and solve their problems here instead of calling a local contractor.

What the heck do you think the Pro technical forum is for? Did you ever possibly think it might be to discuss matters such as this?


Since everyone can get into the pro section what is the difference?

This type of thread is what catches my attention. This is the tread that we can teach each other. Some tech will read this thread and remember that older G20s had an issue with the original control module. Now a few HO's will also. Bitter medicine.


As far if Wishful needs to be helped, not my call. I spend too much time here as it is, and don't need to be policing this site.

[tinknocker service tech]

check the heatexchanger while you are there. the G-20 had problems with deteorating hx. seemed to me it was the hx that was painted that had most of the trouble. lenox later changed it to a nonpainted one and seemed to solve the problem.

[wishful]

Hey folks, I didn't mean to tic anybody off. I have deals with contracttors in this area to help out when they are overburdened or shorthanded. Since I got cancer I can no longer work full time. But a lot of days I feel good enough to be useful, and with some of the young guys needing more experience we can all work together. On that note, I found my tech manual for the Lennox in question, and the furnace will either be fixed right or condemned. By the way-- do you think the average HO would know what flame rectification is, or microamps for that matter.
I was just using this forum to jog my memory. If you do your jobs well & charge a fair price, then you have nothing to worry about.
Thanks again to the good folks with the helpful attitudes.

[lakeman1234]

Steve Wiggins
Professional Member

Registered: Nov 2000
Posts: 4667
Try reversing the polarity. Your 1.4µA reading should go up to 2.8µA
__________________


Steve how do you figure that? If you reverse the polarity on a DC ampmeter you should get -1.4uA. Or are you just trying to be cute? The only time I have seen what you said was when my multimeter went flakey.

Sounds to me like the pilot orifice is pluged up. Try replacing it. We seem to have a lot of problems with them on propane especially in damp basements and Roof Top Units. By the way you should have around 3 to 5 uA of flame current.

[Edited by lakeman1234 on 10-24-2005 at 12:42 AM]

[drfluke]

Don't worry too much madeinusa.
Most homeowners don,t have the proper tools to do the trouble-shooting, much less what to even look for.Just take a look the money you've invested in your equipment to do what you do.Years ago I owned a tire & auto repair business.Busted my --- 15years trying to keep up with Sears,PepBoys,Sams,...etc.When I soldout I had over 50K in equipment and trucks air-compressors,balancers...you name it.Now when I have a flat or a tire out of balance I have to go to someone who's in the tire buisness.Even though I know how to do it..I don't have the equipment to do it.I remember when I worked for a restaurant chain just about every gas fired appliance they had used RobertShaw valves. At the time i could tell you anything you needed to know,but now I'm trying to keep up with the rapidly changing HVAC technology I can't remember that old stuff anymore.I didn't use it,so I loosed it.What's killing me is all these shoddy cut-throat competitors.It's hard to turn a buck anywhere. I can't have the whole pie but I can sure have my piece.Just find your niche and keep a bead on it.Don't be afraid to tell someone what you know, thats how we learned what we know...All of us had to learn at one time too. I visit this site to laugh and LEARN...it's FUN! I've had some Vets on this site save my butt a lot of times just because they wanted to and I really appreciate them.By the time you know alot it's time to die.Don't let all that experience and knowledge go quitely into the night, tell me what you know and your eyes have seen , WE NEED YOU!

[2hot2coolme]

I don't know what kind of advice you guys are giving this poor guy, but you're gonna get him hurt, it's obvious the problem lies in the time delay in the ODFM this is the first thing you want to check before goin through all that other trouble.

Good luck

[joker dan]

check the incoming gas pressure in the house. see what it does when the valve opens if below 4" water colume its a problem turn on other appliances also .may need the meter regulator turned up or keep changing out spark modules like everyone else does LOL. good luck

[Steve Wiggins]

Originally posted by wishful

Thanks again to the good folks with the helpful attitudes.


Yeah we have helpful attitudes alright.....we are helping the legitimate contractors you are stealing work from!

[MikeJ]

Originally posted by wishful
Hey folks, I didn't mean to tic anybody off. I have deals with contracttors in this area to help out when they are overburdened or shorthanded. Since I got cancer I can no longer work full time. But a lot of days I feel good enough to be useful, and with some of the young guys needing more experience we can all work together. On that note, I found my tech manual for the Lennox in question, and the furnace will either be fixed right or condemned. By the way-- do you think the average HO would know what flame rectification is, or microamps for that matter.
I was just using this forum to jog my memory. If you do your jobs well & charge a fair price, then you have nothing to worry about.
Thanks again to the good folks with the helpful attitudes.



Wishful, hope you are hanging in there. Seems like cancer has taken many members of my family on my mother's side. The other side goes out thru other illnesses and heart attacks. Hope you can hang in there and still be useful and productive.

If you are a homeowner and seeking advice, so what? If you get help here once, the next time you WILL probably call a contractor cause the next problem will be more difficult.

Now, with the Lennox G20, I always carry a new pilot assembly, actually several if I can. On any tune up, if I notice that the pilot hood is scorched/blackened/rusted, I suggest to the homeowner that this needs changing now. Why? Because it is a problem waiting to happen, and it will fail in the middle of the night when it is cold out.

Flame rectification cannot be proper with a rusted hood on the pilot cause that is the path (thru the flame) that makes it happen. I don't have the part number handy but it has the small orange wire leading to the pilot assy.

Depending on the model, this can be a chore to change out and I have certain tools that make it easier like a magnetized screwdriver. Any homeowner attempting this change out will end up in the looney bin if they have never done it before. Same goes with the door springs that sometimes need to be taken apart to change the pilot. I think I only removed the door twice in the last five years but I have changed many pilot assy's each year as the Whisper Heats were populare here once.

I would like to meet the design engineer and the ones who authorized this setup. Talk about Job security. The W.H. and the Pulse sure provide it.

To those bashing homeowners attempting repairs all I can say is how often do you attempt something out of your field? We all do it but in the end when the job is major we end up in the yellow pages, don't we?

PS. Wishful, use a good flashlight with a small beam and open the door carefully and look up into the heat exchanger. Many times you will see evidence of cracking at the curve even with the door on. Hard, but can be done.

[lakeman1234]

2hot2coolme
Professional Member

Registered: Apr 2004
Posts: 1460
I don't know what kind of advice you guys are giving this poor guy, but you're gonna get him hurt, it's obvious the problem lies in the time delay in the ODFM this is the first thing you want to check before goin through all that other trouble.

Good luck



This seem off in the twilight zone for advice.

[wishful]

Back in '88 I was boss over 34 technicians, both road and shop. Wish I had the good ones back, but I sure don't miss the cry-babies that thought somebody was cheating them, even though we were all in the same boat. My ligetimate contractor friends keep calling me back, that must count for something. Time to get back to work guys.

[lakeman1234]

Mike J is right. Just hang in there. They are bashing people all the time. Most are afraid some poor soul is going to steal a job from them, or they are going to give that homeowner just enough information to kill them selves. I tend to think you have asked questions that are above the DYI level. Most home owners wouldn't know what flame current is. Personally I don't think some of the "qualified techs" know that either. Good Luck

[Milk man]

Refresh my memory, isn't the G-20 the one with inshot burners and a blue ignition module.

Wish they would just name the furnaces. Everyone know what a whisper heat is.

[wishful]

This furnace has the old style burners and a motorized damper door on the primary air intake.
I changed out the pilot-sensor assy, made no difference. Then I replaced the original Robertshaw ignition module with a Honeywell S8610U. The furnace is now working great, the young man I was teaching was glad to see the whole process, the wiring change can be kind of tricky on some of those modules. Not to mention dealing with that spring loaded damper. Thanks very much for the input gentelmen.
PS; Learning to fly a remote controled helecopter is harder than the real thing--- so I've been told.

Thanks again!!

[MikeJ]

Well Lynn, I sure know what a whisper heat is as I worked for a company that sold Lennox. Learned the hard way how to repair them, at night, alone, in the cold and dark.

Also met a few pulses along the way. I like them.

But the w.h. almost always would need a new pilot burner when excessive clicking was noted or when it was going into lockout. Now with a blue module problem, the symptoms were a little different but it could also result in lockouts. We replaced a lot of them under warranty just because they were there and after warranties expired I would explain to customers why it was beneficial to replace the module AND the pilot burner. Most if not all went along with me and were saved a future service call or two. Once they were replaced, the units usually ran good and dependable unless water got to the circuit board.

However:

"I don't know what kind of advice you guys are giving this poor guy, but you're gonna get him hurt, it's obvious the problem lies in the time delay in the ODFM this is the first thing you want to check before goin through all that other trouble." by another poster may mean that:

I got my head up my whatchamacallit. Anyone got a flashlight?

[Edited by MikeJ on 10-24-2005 at 07:45 PM]

[tinknocker service tech]

th wh i dont think ever had the blue control. as i remember it was the large wr control. it was a very dependable control. wish ful lenox is now useing the honeywell control only it has a build in 30 second delay so the burners can not be shoet cycled in the event of a power flicker. would recomend getting one.
good job and good luck. god be with you

[MikeJ]

You're right about the control,

[curry]

That furnace would probably be better off replaced.

[Milk man]

Now I'm really confused. I was thinking apples where the problem was with oranges.

Does the whisper Heat have both a blue ignition module and a circuit board that hangs on the blower shelf?