Gas furnace Igniter clicking but no spark
#1
02-25-17, 12:25 PM
Gas furnace Igniter clicking but no spark
Hello,
I see Gas furnace Igniter clicking but no spark and it keeps constantly clicking. Nothing comes on. Would you know why igniter is not sparking & once it sparks, the gas valve supposed to open to ignite the furnace fire?
I see Gas furnace Igniter clicking but no spark and it keeps constantly clicking. Nothing comes on. Would you know why igniter is not sparking & once it sparks, the gas valve supposed to open to ignite the furnace fire?
#3
02-25-17, 12:58 PM
Group Moderator
If there is a spark ignition there won't be a standing pilot.
The spark ignition would light a pilot which would in turn light the main burner.
Post the make and the full model number off the ID tag inside on the side wall near the burner.
The spark ignition would light a pilot which would in turn light the main burner.
Post the make and the full model number off the ID tag inside on the side wall near the burner.
#4
02-25-17, 01:48 PM
The only model# info I have is "Day & Night", additional M/N & P/N may be on the side to which I don't have access on either side.
So there is no Pilot-light either, but I hear the igniter clicking sound without any sparks?
Note the draft inducer blower comes on and keeps running and igniter keeps ticking without any sparks.
So there is no Pilot-light either, but I hear the igniter clicking sound without any sparks?
Note the draft inducer blower comes on and keeps running and igniter keeps ticking without any sparks.
#5
02-25-17, 02:54 PM
So "no sparks" from the igniter and so no pilot light, which as I understand would then have lighted the main burner...any ideas why the igniter is not sparking?
#6
02-25-17, 05:22 PM
So inserted/removed 20AWG wire in the orifice of the Pilot-Light & also re-adjusted the placement of the entire Pilot-Light Assembly including the Spark Igniter Rod (SIR), which so far has resolved the problem. I did the same last year as well, not sure why it went bad again....
#7
02-26-17, 01:13 AM
Thought it got fixed as it worked for 3-hours & then it shut down. It appears now that there is no 26vac across the PV & GND. Reads 0.00VAC.
Looks like Honeywell Thermostat CT8602C may be defective. I set it for heat higher than the room temp, I hear a relay click, but the heater does not come on. Any idea what is going on as the heater does not seem to have any power?
Looks like Honeywell Thermostat CT8602C may be defective. I set it for heat higher than the room temp, I hear a relay click, but the heater does not come on. Any idea what is going on as the heater does not seem to have any power?
#9
02-26-17, 07:40 AM
r,
The easiest way to eliminate the thought of a tstat problem is to bypass it. To do this remove the 2 wires from the stat and tie together, bypassing the stat. If the problem persists it was not the stat.
If you have a meter and know how to use it see if you have 24v at the stat when not calling for heat. Have the stat call for heat and check voltage again and see what you get. Although you obviously have power you will get no reading which is what you want. That's another story. Short version is they call it traveling voltage and is normal on these systems.
Hope this helps a little.
The easiest way to eliminate the thought of a tstat problem is to bypass it. To do this remove the 2 wires from the stat and tie together, bypassing the stat. If the problem persists it was not the stat.
If you have a meter and know how to use it see if you have 24v at the stat when not calling for heat. Have the stat call for heat and check voltage again and see what you get. Although you obviously have power you will get no reading which is what you want. That's another story. Short version is they call it traveling voltage and is normal on these systems.
Hope this helps a little.
#10
02-26-17, 08:27 AM
Group Moderator
If you hear ticking but don't see the spark.... would mean the spark is not at the igniter but somewhere else. A possible short at the igniter may allow the ticking noise to stillbe heard from the module.
The ID plate is inside on the side wall near the burner.
The ID plate is inside on the side wall near the burner.
#11
03-04-17, 05:17 PM
Now I do not have power ~24VAC coming the Robertshaw ICU 780-715 U (M/N:SP715/US1715U) heat controller 0r across the PV. I removed the Honeywell CT8602C Thermostat controller and checked its wall mount busplate and measured ~24VAC across "R & G" = 26VAC, R&O = 0.7, R&W = 26VAC, G&O =26VAC, G&Y =26v, etc. I read only 11.6VAC across one wall mount transformer next to the furnace but unable to the white/red wires continuity to the thermostat as they are far away from each other. Thinking of taking 20 ft of wire and connecting to one lead of the meter at the transformer end, and the other meter lead end Thermostat end to check continuity of the wires. Not sure why the transformer is reading only ~11.67VAC. Any ideas.
Thx!
Thx!
#13
03-05-17, 10:44 AM
So per "spott" comments below, I shorted out R (Power) to W(Heat) and sure enough the heater came-on. Thx!
Can & how long the Heater be run long term by forcing call for Heat with a jumper?
Where would be the room-temperature sensor that would detect the room-temp reached and shut down the Heater (ie., open the switch -contacts between R & w)?
What can be done about the Honeywell Thermostat CT8602C?
Can & how long the Heater be run long term by forcing call for Heat with a jumper?
Where would be the room-temperature sensor that would detect the room-temp reached and shut down the Heater (ie., open the switch -contacts between R & w)?
What can be done about the Honeywell Thermostat CT8602C?
#14
03-05-17, 10:48 AM
One more question, what needs to be done to the G (Fan) wire while the Jumper is on between R (Power) & W (Heat), although I do hear the FAN come on? Thx!
#15
03-05-17, 04:12 PM
r,
Nothing has to be done to G wire. The blower will come and shut down when it is suppose to.
As for running the furnace with the jumper there is no danger but it will not shut off by itself. The jumper must be removed to shut the furnace down.
It is not meant for a permanent solution but just for testing purposes. At some point you will have to install a thermostat but in the meantime if you don't mind running it with the jumper there is no danger.
If you don't want to keep jumping the wires you can install the wires on a toggle switch (light switch) and just flip the switch when you want heat. All a t-stat is anyway is a switch with a sensor . You will just have to watch it because you will overheat if left on.
Nothing has to be done to G wire. The blower will come and shut down when it is suppose to.
As for running the furnace with the jumper there is no danger but it will not shut off by itself. The jumper must be removed to shut the furnace down.
It is not meant for a permanent solution but just for testing purposes. At some point you will have to install a thermostat but in the meantime if you don't mind running it with the jumper there is no danger.
If you don't want to keep jumping the wires you can install the wires on a toggle switch (light switch) and just flip the switch when you want heat. All a t-stat is anyway is a switch with a sensor . You will just have to watch it because you will overheat if left on.
#16
03-05-17, 04:44 PM
NO, I do not plan to leave the jumper connected for long. So what is the purpose of the G (Fan) wire?
My understanding was after main-heat burners come-on, then after a short duration, the thermostat turns the blowers-0N by connecting R(Pwr) to G(Fan), is that correct?
Just jumpering R(pwr) to W(heat), how does that make the blowers (fan) to come on?
Would you jump R(pwr) +W(heat) +G(fan) together?
Any idea where I can get the schematics for the Honeywell Chronotherm iv plus Thermostat CT8602C, so that I can troubleshoot it?
Where is the room-temperature-sensor (thermister/bi-metal or? ) that detects the room-temperature and then commands the thermostat to cycle-off heat?
and also Cycles-On or calls for heat when the room-temperature goes below needed room-temperature setting?
My understanding was after main-heat burners come-on, then after a short duration, the thermostat turns the blowers-0N by connecting R(Pwr) to G(Fan), is that correct?
Just jumpering R(pwr) to W(heat), how does that make the blowers (fan) to come on?
Would you jump R(pwr) +W(heat) +G(fan) together?
Any idea where I can get the schematics for the Honeywell Chronotherm iv plus Thermostat CT8602C, so that I can troubleshoot it?
Where is the room-temperature-sensor (thermister/bi-metal or? ) that detects the room-temperature and then commands the thermostat to cycle-off heat?
and also Cycles-On or calls for heat when the room-temperature goes below needed room-temperature setting?
#17
03-05-17, 04:46 PM
Group Moderator
I would keep trying it for several days by shorting the wires.
From what you posted originally.... the thermostat would not be the problem.
R = 24vac.
Shorting R to W puts 24v on W line and is the call for heat.
The furnace will turn on the blower when needed.
When you are in the A/C mode..... you need to short R to G to turn the blower on.
From what you posted originally.... the thermostat would not be the problem.
R = 24vac.
Shorting R to W puts 24v on W line and is the call for heat.
The furnace will turn on the blower when needed.
When you are in the A/C mode..... you need to short R to G to turn the blower on.
#18
03-05-17, 05:45 PM
Hi PJ,
So we have determined that the thermostat is the problem as it shows calling for Heat but does not turn the gas-heater on. It is not internally commanding to connect the R(pwr) to W(heat). As previously stated, I found out that after removing the thermostat and just jumpering R(pwr) to W(heat), turns the heater-ON. This tells me that thermostat is defective.
Also, are you saying G (Fan) is only used during "Cooling", and for Heat I don't need to jumper R(pwr) +W(heat) +G(fan) together?
Please respond to my previous questions on thermostat problems:
Any idea where I can get the schematics for the Honeywell Chronotherm iv plus Thermostat CT8602C, so that I can troubleshoot it?
Where is the room-temperature-sensor (thermister/bi-metal or other sensor) that detects the room-temperature and then commands the thermostat to cycle-off heat?
and also Cycles-On or calls for heat when the room-temperature goes below needed room-temperature setting?
I need to figure out why the Thermostat is not cycling Heat ON and OFF at all?
So we have determined that the thermostat is the problem as it shows calling for Heat but does not turn the gas-heater on. It is not internally commanding to connect the R(pwr) to W(heat). As previously stated, I found out that after removing the thermostat and just jumpering R(pwr) to W(heat), turns the heater-ON. This tells me that thermostat is defective.
Also, are you saying G (Fan) is only used during "Cooling", and for Heat I don't need to jumper R(pwr) +W(heat) +G(fan) together?
Please respond to my previous questions on thermostat problems:
Any idea where I can get the schematics for the Honeywell Chronotherm iv plus Thermostat CT8602C, so that I can troubleshoot it?
Where is the room-temperature-sensor (thermister/bi-metal or other sensor) that detects the room-temperature and then commands the thermostat to cycle-off heat?
and also Cycles-On or calls for heat when the room-temperature goes below needed room-temperature setting?
I need to figure out why the Thermostat is not cycling Heat ON and OFF at all?
