[Spiff59]

Woke up a little frosty this morning.
Furnace is blowing, but no heat.
I pulled the top cover on the SP80 and witnessed the startup sequence.
I see no glow from the smart valve ignoter/flame rod assembly (Q3400) and the pilot never lights. The small motor/fan that gets air flow going is running, and I threw my multimeter across the nearby vacuum switch and it reads open before the fan starts and open once the small motor is engaged.

I'm leaning towards either a bad igniter element or a faulty SV9500 valve.
Can someone help me with the troubleshooting process from this point onward?

Should I read 24VDC across the 2 blue wires to the igniter a few seconds into the ignition sequence?

I've heard about faulty solder joints in the SV9500/9501 series smart valves, and temporary fixes of wedging a shim near the connector. Which way do you push the connector? I was a certified electronic technician years ago and am good with a soldering gun, can the bad connection in the SV9500 be repaired?

Help! It's cold in here!

[Spiff59]

Pardon, the vacuum switch reads closed after the small fan begins to run. (I don't see that I can edit my original post here?)

[greghvacguy]

If your getting a glow you should be getting gas to the pilot. If not check to see if your pilot need to be cleaned. On your gas vaule does the wires come in to top or is one on the side. If you have one on the side yes they have bad connection try and to wiggel it.I Don't Recommend ON FIXING ANY GAS VAULE GET NEW ONE.
Sounds like your proplem is in pilot or gas.
Hope this helps

[Spiff59]

If your getting a glow you sould be getting gas to the pilot. If not check to see if your pilot need to be cleaned. on your gas vaule does the wires come in to top or is one on the side. If you have one on the side yes thay have bad connection try and to wiggel it.I DONT RECOMEND ON FIXING ANY GAS VAULE GET NEW ONE.
sounds like your proplem is in pilot or gas.
hope this helps

Nope, no glow. I pulled the connector to the ignitor element and the ohmeter is reading an open connection. I would think a good one would read 20 or 50 or 100 ohms? Some value of resistance other than infinite? The connector has 2 blue wires to the ignitor and one copper (clear insulation) going to the sensor on the same assembly, it inserts vertically on the top-right of the SV9500. I pulled the ignitor element and it still tests open, and I can see a small line going across one side of the element up near the tip, not sure if it's a crack, could be?

Advice?

[Spiff59]

How smart is a Honeywell SV9500 smart valve?

The heating element on my flame rod assembly is cracked, it doesn't glow and it tests as an open connection.
So, to bring the temperature around here above 50 degrees, I thought I'd manually light the pilot, and get one free heating cycle to bring things up to a more comfortable temperature around here. Then, Monday morning I'll chasee down a Q3400 flame rod/sensor assembly.

I expected to have gas flow at the pilot within the first fes seconds of the furnace starting, which I'd manualy light and throw the cover on before the sensor opened up the main gas flow. I'm not seeming to have any gas flow at the pilot. Is the SV9500 smart enough to detect a cracked (or what it might conside a missing) flame rod and not engage gas flow to the pilot?

I'm somewhat suspicious that I'd happen to have a dual-failure at the same tme (both flame rod and smart valve)

[hvac1000]

Smart valves have had many problems. The nick name is Dumb Valve in the trade. If you have one of these they are junk also.

[Spiff59]

Yes, that's my ignition system, and the HSI is cracked. I'm guessing the SV9500 detects that the HSI wires are showing an open connection, and therefore won't provide gas to the pilot. So, I guess I won't fooling the furnace into providing some heat prior to Monday. I'll take your word that the SV9500/Q3400 setup isn't the sweetest, but I just want to fix what we have, not replace the entire furnace. I'll stick in a silicon nitride replacement Monday and expect that'll patch me up for a while.

[hvac1000]

I hope it works out for you.