Tempstar furnace no heat.
Hello folks.
We have a temp star NG furnace in one of our small storefront units and it was installed over 20 years ago and has worked flawlessly since.
Yesterday we tried to turn on the heat and the furnace comes on and I hear the ignitor sparking but we get no flame.
Any easy checks before we have to call the pro?
Thanks in advance.
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci
Comments
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Make sure the gas is turned on.
I would then check for 24 volts at the PV (pilot valve) terminals on the gas valve and also the PV terminals on the ignition control module on the right hand wall in your picture.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab
2 -
Does it just spark & not light at all, or does it light for a few seconds & then go out?
2 -
I would say if that is in a commercial environment that you should have a competent professional clean and test the safeties on that in addition to figuring out why it won't fire. I would start by making sure the gas service wasn't turned off over the summer.
1 -
Spark and no light at all
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
I checked that the gas is on. They also have a gas water heater that's working.
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
Wiggle or unplug & plug back together all the connections & try it again.
If that doesn't fix it, check for 24 VAC from "MV/PV" to "PV" when it's sparking. If there's power there, the controls are operating and it's either a bad valve or possibly a clogged pilot orifice. Do you smell gas when it's trying to light? If there's no power to the valve, make the same checks on the terminals of the ignition board, if there's no power there the board is bad.
1 -
Do you have an electrical meter? You need to see if there's 24 volts going into the ignition control module, then 24 volts out to PV and PV/MV at the gas valve. The spark will attempt whether there's gas there or not. You should be able to hear or feel the gas valve energizing.
I am going to roll the dice and say the burner circuit is open on the pressure switch due to a squirrel in the flue.
1 -
I can say that blower assembly needs to be remove and cleaned.
2 -
The entire thing needs a good cleaning but that may or may not be causing the issue of not lighting. Many think gas never needs servicing.
2 -
22 years young
When was the last time it was serviced?
1 -
This wiring diagram may help if you have a multi-meter.
Some troubleshooting information here, Honeywell S8600 Intermittent Pilot Module .
https://customer.resideo.com/resources/Techlit/TechLitDocuments/69-0000s/69-0463.pdf
The spark only lights the pilot. Check for the presence of the pilot, if it lights and goes out the igniter / sensor rod may need cleaning, pilot quality, pilot orifice restricted, loose ground wires. No pilot at all, plugged pilot orifice, electrical issue, S8600 issue, gas valve issue .
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
The furnace stopped all of a sudden! after over 20 years of operation, without looking at the flame sensor for all that time, all of a sudden 20+ years it got fouled up with some kind of film or covering today! and if you take something like a Scotch-brite and rub that film off, it should last another 20 years.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
1 -
Never. 🤣
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
I don't think it has a pilot....🤷🏽
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
Oh, it definitely has a pilot. That’s what the 1/4” aluminum tube from the gas valve is feeding.
The spark lights the pilot, not the burners.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
1 -
The tube (Red arrows) goes from the Gas valve to the pilot assembly. If the pilot does not light and prove for a period of time the burner will never light. The Blue wire to the Right of the pilot assembly in the picture goes to the igniter / sensor rod at the pilot assembly.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
I'm getting 39-40 volts between pv. And mv/pv at the gas valve.
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
Well it looks like I am taking that apart. Haha.
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
Don't know if this is bad but it looks old enough to replace. Lol
Homeowner, Entrepreneur, Mechanic, Electrician,
"The toes you step on today are connected to the butt you'll have to kiss tomorrow". ---Vincent "Buddy" Cianci0 -
the pilot is not lighting and you don't smell gas? either you have no gas to the appliance, the valve is bad, or the pilot orifice is plugged if there is no gas smell or sound.
0 -
Has that pilot burner ever been under water?
That would mean the main burners were under water too and possibly the gas control valve
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
0 -
this looks like something that will work
You may also need a new spark cable since the blue one may not be the type that will disconnect from the old and connect to the new
Here is the part: Honeywell/Resideo Q345A
Here is the replacement cable 25" Ignition cable
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
0 -
Is there a gap between the probe and the shell of the pilot burner?
0 -
That is not the reading you want. At the circuit board with a call for heat , measure across C and W. It should be 24-28 volts. Also measure across R and W. It should be 0 volts. Anything other than 0 is a problem.
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39-40 volts seems oddly high. Does your meter work correctly ?
During a thermostat call for heat there there should be a nominal 24 VAC across C and W and C to R (Red box), if not verify the 120 and 24 VAC at the transformer (Orange box). In normal operation with normal voltages the control board applies 24 VAC to the S8600 Intermittent Pilot Module at the 24V & 24V GND terminals (Green box) which seems like that was happening since you were hearing spark. During the spark the S8600 Intermittent Pilot Module applies 24VAC to the PV & MV/PV terminals of the gas valve (Blue box) the pilot should then light. After the pilot is active for the trial time the S8600 Intermittent Pilot Module applies 24 VAC to the MV & MV/PV terminals to open the main gas valve. That pilot assembly looks excessively crusty, may work OK if cleaned up. Would not surprise me if the pilot orifice is corroded closed or blocked.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0
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