furnace burner goes off then on

[dpgerson]

I have a 2000 Snowbird with an Atwood Mobile 8535-IV-DCLP furnace. When operating the burner will burn for awhile then stop then start again, and continue this pattern until it reaches temperature. The fan stays on during this whole time.

Is this normal to have the burner go off and then on until temperature is reached? Or do I have some other problem brewing like a bad control board?

[Chuck_thehammer]

Old-Biscuit wrote:
Typical 2 stage LP Regulator has a 160,000btu flow rating

The GREEN ACME nut on pigtail hoses have a 200,000btu flow rating

LP Regulator should be preset for 11" WC (roughly 0.4 psi)

IF pressure to high then furnace COULD overfire/overheat
BUT same problem would be with water heater, fridge and stove top burners.

Airflow........Obstructions (Usual cause)

Thank You Sir,

will do cleaning and inspection.. when I get home..
only Furnace has issue.. right after regulator replacement...

[dpgerson]

Darn it old biscuit, I was just in Cottonwood! We could have had a cup of coffee. I will start looking for obstructions. I may have more questions.

[Old-Biscuit]

Typical 2 stage LP Regulator has a 160,000btu flow rating

The GREEN ACME nut on pigtail hoses have a 200,000btu flow rating

LP Regulator should be preset for 11" WC (roughly 0.4 psi)

IF pressure to high then furnace COULD overfire/overheat
BUT same problem would be with water heater, fridge and stove top burners.

Airflow........Obstructions (Usual cause)

[Chuck_thehammer]

I just started to have this issue... last month...

just replaced propane regulator... and furnace started this issue..

being in south Texas .. will clean and check in a few weeks when I return home.

or are there different regulators????
I took old one to RV dealer.. so he could offer the proper replacement..

my trailer has twin 30 pound tanks on the "A" frame, if it matters.

[Old-Biscuit]

It is called 'limiting'........operating on the high temp limit switch

Heat exchanger gets too hot (190*F in your case) and high temp limit switch opens shutting down burner. Fan continues to run, cools heat exchanger/high temp limit switch closes....burner refires cause t-stat set point has not been reached yet

This is typically due to blocked airflow..either floor registers closed, return air obstructed or duct work restricted.

Bad limit switch would just shut furnace down or NOT allow it to run in first place.

Airflow.....
If fan not running fast enough sail switch would not make up....no furnace operation at all

Obstruction. Find it/clear it up

[time2roll]

Need more airflow. Either inadequate ducting or an obstruction.
Long shot is the high limit switch is bad or blower.

[wing_zealot]

I don't know about your furnace in particular, but generally if the heat exchanger gets to hot, the gas will shut off until the heat exchanger cools down some. The heat exchanger could be getting to hot because the air blowing over it is to warm to begin with, because the fan isn't blowing enough air over it, or the air is restricted in some way.
It's more common for the fan to run intermittently when the return air is to cold such as in cold weather and just starting the furnace in a really cold house. In this case the heat exchanger is getting to cold to fast.

[Artum_Snowbird]

Not normal at all. Sounds like perhaps an overheat sensor is cutting the burner off even though it hasn't reached the temperature required. As it cools a little, the sensor allows it to go again.

Check it out carefully for plugged air flow perhaps, bad sensors, or a slow fan.