Original message
| Chuck78
 |  "older Bryant/Carrier spark ignition questions"
, posted Mon 14 Jan 18:30  
I've now come across my second old Bryant furnace (late 80's) with the spark ignition (intermittent pilot) and the three wires going to the pilot module (white, yellow, and green?), plus the big orange spark wire.
Fortunately, it seems as if I took care of the problem by going where the other two techs would not go, the very cramped impossible to get to burner compartment... (1988 model 90+ Bryant). That was a real pain in itself, just dismantling the thing to get to the ignition! Cleaning the ground and the ignition parts, and adjusting the spark gap seems to have done it. It never acted up one bit for me (or the other guys), but apparently would go into lockout in the middle of the night all the time, inducer fan/motor on, no pilot (according to customer's son). No diagnostic LED on the board on these old ones... It was made a little easier for me since both boards were new, the ignition board as well, gas valve, pressure switch, and stat! That helped narrow it down a bit! I was a little afraid of a slow draining condensate hose or collector box or something, that would only manifest itself in the form of pressure switch not closing on really long run times... I cleared out the hoses, but they looked good.
I had heard of having to flush out the older secondary heat exchangers, and was fearing that.
Anyway, after seeing a few of these, and not really knowing exactly how they worked, I was hoping someone could explain a little bit. Is the ignition rod piece also the flame sensor? I was never sure how they worked, but that seemed the only likely thing. What are the three wires? I gather that one is probably a common wire, and then the two others are for the pilot proving and main valve proving? Is there a relay built into the ignition /pilot piece? Briefly scanning the schematic, I think I recall seeing something like that. A little background and sequence of operations on these things would be greatly appreciated.
Also, what is the purpose of the tiny little circuit board that sits in the little compartment behind the pressure switch on these things?
Thanks for clearing things up!
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Replies:
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| static
| "Re(1):older Bryant/Carrier spark ignition que" , posted Mon 14 Jan 20:43
You've pretty much got it.
The board behind the pressure switch (inducer board) is more or less the ignition board, the other one is a fan timer.
On the original inducer board, the orange wire going to the auxillary limits powers it, on the updated one, there is a red wire you add to the top slot in the edge connector and run it to the main limit that powers it.
The pilot does have a relay, it is heat activated (warp bar), it is in the bottom of the three-wire pilot module. The sparker is just a sparker, the heat activated relay is how it "senses" flame. Yellow is the common. Green "picks" open the pilot valve when the pilot module is cold. White opens the main valve when the module heats up. The warp bar is what makes the switch.
The HOLD terminal: To keep the pilot valve from dropping out when the pilot module switches, the gas valve also has a "hold" terminal, it holds the pilot valve open. This terminal is controlled by the inducer board and is energized whenever it senses a closed pressure switch. So upon start-up, pick and hold are energized simultaneously, then hold remains energized while the pilot module switches power from pick to main.
Once the pilot module switches you hear the "clunk!" when the main valve is energized, it is a slow opening valve, so it takes 10 - 15 seconds to open. The signal is relayed down the other white wire connected to #1 to let the fan timer board know what's going on. If you hear multiple clunks, the pilot module probably needs cleaned, down where the warp bar is.
Those old 90's are a royal pain to get to the pilot, I'll agree wholeheartedly. Especially the downflow ones. They make a "Recycle Timer" for the problem you're having with that one (recycles after lockout) but I don't have a part number handy. I would recommend to check on the secondary by pulling the collector box and / or the blower first.
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| | RJAY
| "Re(2):older Bryant/Carrier spark ignition que" , posted Mon 4 Feb 19:21
Static:
Thanks for your help--You did say that there is a Recycle Timer for these units--my Carrier 58SX will drop out(the flame)after heating up (running for some time) and then the ID fan will not shutdown. Of course the condensate cannot drain away and then the unit will not restart until I power everything down.I let the water flow away and then it restarts fine. Does the Recycle Timer allow for a total shutdown and then restart, if so this sounds like the fix for my old CARRIER.
If you come across the part # --maybe you could post if you have a moment. Many thanks
Randy
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| | static
| "Re(2):older Bryant/Carrier spark ignition que" , posted Mon 14 Jan 20:59
Now in that first picture I should have called Green "normally closed" and white "normally open", so my bad.
Also if Houston204 sees this, he has some pretty kickin it wiring diagrams he might post one or two of on here.
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| | northernfitter
| "Re(3):older Bryant/Carrier spark ignition que" , posted Sat 19 Jan 19:51
I have that model in my basement I have used it as a marker on sales calls. I have a 20 Year old bryant in my basement thats still working and has all the original parts(never mention that I would hate to have to screw around with that annoying pilot). Sadly going to replace it soon as I am selling the house in the summer. Putting in a plus90i with Bryants top end filter because two of my foster sons asthma has gotten bad and I am concerned about airborne contaminants ie mold and such, house is 130years old.
12years as a service tech in Ottawa and the valley. Just left Direct Energy to start my own company. Go to www.reliableheating.ca or email me at adrian@reliableheating.ca
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