furnace cycling

[jkmech]

my furnace cycles on and off . it runs 10 minutes then shuts down for ten minutes and then starts again for 10 minutes contuinues the same way . any ideas?

 

[anthony666]

oversized

 

[brewchief]

Does it maintain temperature operating like that?

 

[mygarageone]

not near enough info to make an assessment.
Did this just start ? is this an older furnace ? what brand , hi eff or what ? have you changed the filter lately ?
Give us some details.

 

[Showkey]

+2 ^^^^^^^^

But:

Did you install a new thermostat recently ?????????

 

[zmaxmotorsports]

my furnace cycles on and off . it runs 10 minutes then shuts down for ten minutes and then starts again for 10 minutes contuinues the same way . any ideas?

Does it completely shut down,or does the blower keep running until the furnace starts up again?

 

[JRC3]

Does it have a flame rod/sensor? If so clean it. Remove it and clean it with a cloth or a dollar bill. It may look clean but it can be dirty, you wont see a bunch of buildup on it. They don't work like a thermocouple as they sense current (ground) through the flame itself and it doesn't take a lot to lose that continuity.


Could also be a blocked flue or cracked heat exchanger tripping the high limit switch.

This guy is awesome and his site links his Youtube vids. http://www.grayfurnaceman.com/ I've learned tons from him.

 

[jkmech]

furnace is a frigidare gas model g6ra it is about 5 yrs old. after problem started replaced thermostat no help. cleaned flame sensor and checked it is working normal. all limits switches are good does not trip high limit switch. furnace starts normal and runs for about 3 minutes then flame shuts off and furnace blower motor and induction motor stay on till furnace cools down. wait about 5 to 10 mins. and it does same thing again same way .keeps doing this till house gets up to temp selected.

 

[JRC3]

Sounds like the board but who knows. I'd still check the flue for rollout and the exchanger for cracks.


Might be time to check water column line pressure or at least check btu flow timing at the meter for that appliance. If it's low, maybe the furnace's regulator's screen is clogged. Has there been main line service in your area?

 

[zmaxmotorsports]

How often do you change your filter,could A coil be clogged?Maybe try pulling filter out and see if it will stay running.

 

[zmaxmotorsports]

Where are you located?

 

[lametec]

Does the board blink a code?

 

[Stuart in MN]

How cold is it outside?

 

[mygarageone]

Yes I does sound like an air flow issue. If the filter wasn't changed often , you could have very dirt secondary or a coil.

 

[zmaxmotorsports]

Sounds like the board but who knows. I'd still check the flue for rollout and the exchanger for cracks.


Might be time to check water column line pressure or at least check btu flow timing at the meter for that appliance. If it's low, maybe the furnace's regulator's screen is clogged. Has there been main line service in your area?

 

[MDI09]

https://www.google.com/search?sourc...hp..3.0l5.0.0.0.11125...........0.FKrSpoJbPt4

 

[BillK]

jk,
Just went through the same issue with my house furnace. Turned out to be a combination of a dirty pre-filter for the electronic air cleaner combined with a lot of buildup on the circulating fan. The combination caused the furnace to go into an over temp shutdown and it would do exactly what yours is. My go-to HVAC guy told me to take the filters out and see if it took care of the problem, which it did. After cleaning the filters it was a lot better but still did it once in a while. He told me to pull the blower and clean it real good. He was right, there was some buildup on the fan "blades" apparently just enough to cut down on airflow some.

Pull the filters and see if it acts ok. If so, you will know that you have an airflow issue.

Hope this helps,

 

[bonneyman]

Newer furnaces and air conditioners are very airflow sensitive. This becomes more pronounced as higher and higher SEER rating equipment is installed on older homes.
Using the right filter and keeping it clean/replaced religiously is vital. Especially in heat mode. Low airflow while using the furnace can easily lead to an overheat condition. Not good!
But even if you're spot on with filter maintenance, you should still have your evap coils cleaned every 5-6 years. Because no filter catches 100% of the dirt.

 

[theoldwizard1]

... does not trip high limit switch. furnace starts normal and runs for about 3 minutes then flame shuts off and furnace blower motor and induction motor stay on till furnace cools down. wait about 5 to 10 mins. and it does same thing again same way .keeps doing this till house gets up to temp selected.

jk,
Just went through the same issue with my house furnace. Turned out to be a combination of a dirty pre-filter for the electronic air cleaner combined with a lot of buildup on the circulating fan. The combination caused the furnace to go into an over temp shutdown ...

I'm with Bill. Sound like an over-temp shutdown.

I have a similar problem, but mine is a duct work design flaw (2 90° turns coming out of a horizontal furnace befor heating the main trunk line). Luckily t only happens ocassionally.

 

[bazar01]

I'm with Bill. Sound like an over-temp shutdown.

I have a similar problem, but mine is a duct work design flaw (2 90° turns coming out of a horizontal furnace befor heating the main trunk line). Luckily t only happens ocassionally.

+1.
If it's not a dirty A/C coil or low air flow due to dirty filter, the flame is too high. Can you throttle the gas **** a little?