Propane Furnace Cycling

[lagunamiata]

Our 2016 16rb does something similar. We bought a small electric heater, it works fine and heats the camper without issue. No need for the propane heater when we're connected to shore power.

[Houston Remodeler]

In our model, the sail switch is well hidden, right aside the squirrel cage blower inside the black plastic housing.

[Tardis-1]

So … sail switch “lies” and signals no air flow (even though there is), so burner shuts off. Sail switch then (later) signals air flow fine, burner re-ignites. Hmm. Is sail switch in the heat path so it could heat up - present faulty no airflow signal - cool after burner quits and then function properly? That would explain always proper startup (sail switch cool) and problems when hot airflow occurs.

[Houston Remodeler]

Not true on #3 faulty sail switch.

We were in Yellowstone in early May 2016. Ice and snow daily. The heater worked fine until day 3. Would work for a bit then just blow air. Work for a bit, then blow air. Restart did the same thing or not heat at all.

Pulled it apart and found the sail switch had scorched marks. Replaced it. No problems since. $8

[GaryG]

My trailer furnace fan runs a bit, maybe a minute or two after the gas burner shuts down to be sure the furnace had cooled enough. This prevents the furnace exterior from getting too hot and possibly cause a fire. That's my opinion.

[Tardis-1]

I have a question regarding the propane furnace operation. One does not know if there is a problem until one learns “that’s not right”. Many thought of ‘issues’ have been discovered to be ‘normal operation’.

BTW, brand new 16RB, and it has always done this. Bear with my verbosity.

My propane furnace burner cycles during operation. Now, let me state I know the fan starts, burner comes on later, and after the burner shuts off, that fan continues to run for a bit.

What I am talking about is the fan continues to run because the thermostat has not been satisfied, yet the burner cycles on/off every few minutes, until the thermostat has been satisfied, then the whole system shuts down properly.

In your house, the burners fire continuously until the thermostat has been satisfied, then shut off, and sure, there is a bit of fan running to clear residual heat exchanger heat.

But in a small RV would the burner normally cycle ON/OFF. That could be normal operation - inject flame heat just often enough to keep the output air temp at its target.

Now, I know about some possible errors: 1) reduced air flow causing the hi-limit switch to kick off burner, temp falls, hi-limit switch allows burner re-fire, repeat, 2) faulty hi-limit switch freaking out at actually too low of a temp, forcing burner cycling when its actually not necessary, 3) faulty sail switch, but then it never fails to ‘start up’ properly.

But the key question: Is this NORMAL or ABNORMAL (or Abby Normal as Igor would say).

Bottom line, the furnace does the job of heating the interior, all the way from proper startup to proper shutdown - and it maintains the thermostat requested temp properly - it just cycles the burner WITHIN the thermostat requested heat cycle.

I could see where you would not need 500-degree flame full time to average 130-degree air, so maybe the burner is supposed to cycle.

Please help me determine if I have a problem or if this is normal.

BTW, the local dealer has been ineffectual after the sale, and I’d rather not go there, and calls to Starcraft meet with resistance because they want me to go to the dealer.

Edit:

I should add more … (OMG, add more?)

This is much more apparent upon first heat at cold campsite, where the furnace will run much longer to heat cold everything as opposed to short runs to maintain the air temp once everything is warmed up.

Does the burner cycle during that 10-15 minutes, yes. Does it cycle during a three-minute top off cycle, not so sure.

So it definitely cycles during a prolonged call-for-heat, it may not during short maintenance runs.