19 year old Tempstar 867769446 NUGK125DK07 nat. gas furnace with Honeywell S8600M Controller located in Salt Lake City, currently 39 deg F:

Good morning:
Looking for suggestions on the following:
1) Thermostat calls for heat.
2) Electronic igniter starts.
3) Honeywell S8600M Controller PV output goes to 24VAC.
4) Pilot Valve opens.
5) Pilot flame starts, then after at most ONE SECOND:
6) Honeywell S8600M Controller PV output goes to 0 VAC.
7) Pilot Valve closes.
8) Pilot flame goes out.
9) 4 seconds later, the entire sequence starts again at step 2)

--The above sequence goes on, over & over, continuously, until the thermostat is set down below current room temperature.
--The Main Valve never opens.
--The Pilot flame is a nice steady blue flame which envelops 1/2 inch of the igniter-sensor tip.
--The issue started happening intermittently about 2 weeks ago, got progressively more frequent, and is now a solid issue. (At least it's not intermittent- hate those).

What I've done so far:
--Replaced the igniter-sensor, re-verifying the pilot flame is a nice steady blue flame which envelops 1/2 inch of the igniter-sensor tip. No help/same problem.
--Re-seated all electrical connections in and to the entire furnace. No help/same problem.
--Verified a solid 24VAC is present at the Honeywell S8600M Controller's 24V input.
--When I temporarily re-route the pilot valve, then main valve connections directly to the 24VAC line, bypassing the Honeywell S8600M Controller (yes I know: safety exposure- it's just test) then both the pilot and main burners light, air system runs, and we have heat.

Other current issues with this furnace:
--Exhaust blower vibrates, which started many months ago. Appears the plastic impellor is cracked, but it still works and the air pressure switch stays closed OK.
--Flue Limit thermal switch has on occasion opened when there is no flue over-temp condition. I address this about once per year by gently re-cleaning the switch contacts with 600 grit sandpaper. Currently I measure a solid 0 volts across the switch contacts; it is properly staying closed.

Questions:
--Does the ignition issue sound like the Honeywell S8600M Controller has failed (flame detector/relay driver hybrid circuit failing to read the flame sensor?)
--Considering the age of the furnace, the above issues, and whatever efficiency improvements have been made in the last 19 years, would it make sense to replace the entire furnace?
--Is Tempstar a low-quality product? Over the years, I have had to replace its fan control module and fan relay (on separate un-related occasions years apart), now it has the above issues. Are all brands this service-intensive?

Thanks.

 

Yes, it's probably a bad ignition module.


All furnaces have issues. The NUGK has a lot of discrete components compared with other furnaces today, or even at the time. Replace the circuit board on a furnace today, and you renew many of those components. Replace one discrete component and you still have all those other old components.

This was the common way of building furnaces until purpose built circuit boards controlling most furnace functions were developed. So this is an older method of design, which has some limitations as described.

Personally, I'd be inclined to replace the furnace module rather than the furnace. I actually have the inducer assembly for this furnace as left over inventory from my now closed repair business ----I'd sell that for $110 including shipping if you're interested. I might even have the ignition module if you were interested.

So repairing the furnace is practical. Replacing it is worth considering as you are doing.

 

Thanks for the reply, advice & offer.
Please clarify:
You are offering the inducer assembly (what Tempstar & I refer to as "Exhaust Blower", P/N 1005150) for $110 including ground shipping to Salt Lake City, correct?
And you say you might also have the ignition module:
--(using Tempstar factory part #'s and names): P/N 1005651 Module, Control (Nat.)
or:
--(using the Honeywell factory part #'s and names): S8600M Continuous Re-try 100% Shutoff IP 90 Sec. Trial For Ignition.
Please check if you have this item and tell me how much you would ask for it.
Thanks.

 

Photo:
http://home.comcast.net/~tomdempster...olderJoint.jpg

I found a bad solder joint on one of the relay legs on the Honeywell S8600M Controller board. Actually, on closer inspection, several of these relay legs had solder joints showing signs of cracking, but the one in the above photo was completely open. It would be nice if Honeywell (or whatever overseas garage operation they farm their manufacturing out to) would do a better job of solder flow before they coat the darn thing in plastic; whatever the plastic-like coating it is they dip the board in makes it difficult to touch up their lousy soldering, but I got it working.
Thanks.

 

Just to double check, the furnace you have vents using plastic pipe, right. That's the NUGK condensing furnace according to my recollection.


As it turns out, I don't have the ingiition module. I do have the Part number 1011350, which is a later version of the original 1005150 part number.

You can see that here:

A173 Heil 7162-2782, 1011350, FB-RFB350, 7062-4578, 7062-4832, 10073


So yes, I'll ship it for that price. I'd need a money order for $110.

I've been posting here for years and I think others would say you are taking a reasonable chance by sending me money.

 

You say it had lousy soldering. The whole board? Or just that joint? I am one to open up bad modules and look at boards. And from my experience, they all look very perfect. Probably done by a machine. Have exact uniform amount of solder at each connection, and each 'dab' looks the same. And since connections are teeny fractions away from each other, it has to be perfect. Could it be possible that some electrical surge, or other cause, 'took out' that connection?

That coating will help guard against moisture, or tiny conductive strands(of some sort or another that might get into or onto it) from shorting out the board, and will prevent oxidation.

If the same problem at the same spot crops up again in the future, be sure to let us know. That way we will know if it was truly a bad joint, or if an outside acting force made that joint go bad.

I have to congratulate you for being handy enough to make that repair. Did you use an intrument or tip for more fine work?

Some years back I fixed a board in a garage door opener. All I had to do is remelt the solder that was already there to get it to reflow, to resolder the broken diode solder-to-wire connections. From my memory I do not believe that board was plastic coated.

 

The photo you can see at: http://home.comcast.net/~tomdempster...olderJoint.jpg
... shows the failed solder connection that was the cause of the igniter control failure. This is one of the relay legs associated with the board's output to the Pilot Valve. My ohm meter showed the connection was completely open. As I reported in the original post, the symptom started intermittently, then progressed to more frequent, then a solid failure, so I think the connection failure was a gradual progression. I have seen this exact cracked solder joint issue with power connections in other appliances, such as a Franklin Ice machine's compressor-relay connection I fixed last month. I used a solder sucker to remove most of the old solder and then resoldered using a 40W pencil style iron. Like you say, most of the solder connections on the board were fine, but using a magnifying glass, I could see other relay connections that were beginning to crack also, so I touched them up in same fashion. Solder is only a tin-lead alloy, which is not a metal conconction capable of withstanding years of electrical current-induced thermal expansion & contraction, combined with vibration from the relays themselves opening & closing thousands of times plus general vibration from motors elsewhere in the furnace.

 

Correct: vents using plastic pipe.
SeattlePioneer:
I just added you to my contacts, in case my exhaust fan condition worsens. Your price beats the other on-line prices I've found by far. I'm hoping my fan will hang together at least until I'm too senile to deal with it any more, in which case it will be my kids' problem.

 

That's kind of nice for everyone to know, who has everything run in their houses and cars today, utilizing such boards.

 

Own a Utica Boiler for 16 years with S8600M module. Noticed multiple restart issues after about 4 years. My service guy was not concerned. Ran another 4 years with intermittent issues. Could hear high voltage arc during ignition. Inspected circuit board and noticed a failed solder joint. Resoldered. Called service guy to order new board. He said they never go bad. Must be a fluke. 2 am last night, boiler kept cycling. Pulled board and found another failed solder joint. Resoldered and went to bed. Can I purchase this part myself and where. P.S. I Donald Trumped the service guy.

 

You can purchase it from a local HVAC parts reseller or find one online. There are many online companies selling that board. When ordering you need to use the entire part number as it makes a big difference.

North America Hvac
Enter S8600M in their searchbar.