heater Fan Run Time

[jake2250]

I searched but cannot find an answer,,

It seems that my heater fan comes on before the heater lights off. The fan runs for almost 40 seconds then you can hear the heater light off, when it reaches set temp you can hear the flame shut off but the fan continues to run for up to a minute!!
So it starts blowing cold air then ends by cooling everything off again.

My question: Can I adjust fan run time?

On our Pop Up trailer the little heater fan would come on for like ten seconds then the heater would light, then at temp set the flame would go out and fan would only run for about fifteen seconds..

[jake2250]

Sam Spade wrote:

jake2250 wrote:

So it starts blowing cold air then ends by cooling everything off again..

If the air coming out really IS colder than ambient, then you have TERRIBLE insulation on your ducts and that needs to be fixed.

The fan runs a bit extra before and after to get all of the heat out of the heat exchanger and into the living area. It may FEEL cold but hopefully really isn't. Do an actual measurement to be sure.

Thanks, I did exactly this today,, 50 degrees out side 50 inside trailer, turned the heat on, fan runs about 30 seconds then ignition,,heat comes up from the vents at a maximum of 89 degrees, runs to set temp of 55 (thermostat is close to actual temp) then the flame goes out, fan runs for 75 seconds then shuts off,, during the cool down run on temp coming out of the vent was at 72 when it shut off!! SO Yes its functioning perfectly and I just thought it was blowing to much cold air but its not!!!
Thank You every one that commented!!

[Dennis12]

Mine was doing the same thing until i had the limits set on my thermostat. Now mine is like allicanafford, it runs about 15 seconds before flame lights, and about 30 seconds after flame off.

[Sam_Spade]

jake2250 wrote:

So it starts blowing cold air then ends by cooling everything off again..

If the air coming out really IS colder than ambient, then you have TERRIBLE insulation on your ducts and that needs to be fixed.

The fan runs a bit extra before and after to get all of the heat out of the heat exchanger and into the living area. It may FEEL cold but hopefully really isn't. Do an actual measurement to be sure.

[NanciL]

That is law per the National Electric Code in regards to combustion controls and is used on every gas fired furnace that exists including those in large generating stations.
It has nothing to do with removing heat. It is a safety device to remove any gasses prior to light off and any after shut down to prevent an explosion.

Jack L

[bobndot]

If it really bothers you, see about doing something else for heating your TT. Look into (see if they are still avl.) a Platinum vented cat heater.

[Huntindog]

Some people have replaced the thermostat with a digital one to reduce the temp. swing.

If you boondock, there is a downside: This mod makes the furnace cycle more frequently. And since the fan MUST run before and after each cycle, more cycles means more electricity used. Boondockers usually try to conserve electricity, so it is a negative for them.

[Strabo]

Normal part of camping in cold weather with your heater. Mine does the same thing.

[rbpru]

You will find most thermostats have a rather large temp spread between off and on and off again.

Tape a cheap thermometer to the thermostat and watch the temp spread. The smaller the space the more noticeable the temp swing.

[All_I_could_aff]

Keep in mind that the blowing air always seems cooler than it is, so after the flame shuts off, you might think it's blowing cold, but may be 80 degree air.

Plus, remenber that the furnace is recirculating the interior air over the heat exchanger, not pulling in fresh air, from outside.

Mine runs about 15 seconds before flame lights, and about 30 seconds after flame off.

[Trackrig]

trail-explorer wrote:

jake2250 wrote:
Yes,, thats my issue, If I could reduce the amount of fan run on after the flame goes out it would retain the heat. Instead it feel like it is blowing off the heat generated.

It's blowing the generated heat (from the heat exchanger/flame chamber) into the RV... so I'm not sure what's bad about that.

It's a safety function to cool off the heat exchanger before shutting down the fan. I'm sure it's probably a safety requirement of the UL.

Home gas furnaces operate the same way.

X2 - you're not loosing any heat, the fan is just circulating the air while the furnace cools down. As the air circulates while cooling the furnace, you're probably getting a little bit of free hot air because the furnace is no longer burning propane.

Bill

[Old-Biscuit]

Fan runs at first to 'purge' combustion chamber of ANY possible fuel ---safety feature.(SO no explosion occurs)

Fan continues to run AFTER fuel shuts-off to remove excess heat from heat exchanger to cool it down----again another safety feature (fire hazard)

One motor runs TWO fan wheels . One for combustion side and one for room air side, so when motor runs both wheels move air

NO you can NOT change the 'purge' or 'cool down' time ---factory preset

[trail-explorer]

jake2250 wrote:
Yes,, thats my issue, If I could reduce the amount of fan run on after the flame goes out it would retain the heat. Instead it feel like it is blowing off the heat generated.

It's blowing the generated heat (from the heat exchanger/flame chamber) into the RV... so I'm not sure what's bad about that.

It's a safety function to cool off the heat exchanger before shutting down the fan. I'm sure it's probably a safety requirement of the UL.

Home gas furnaces operate the same way.

[jake2250]

RavensFan24 wrote:
Mine works the same way. My wish is that the thermostat would show the ACTUAL temperature in addition to the set temperature. When the heat runs, I feel like it gets super hot (well over how it was set) and then it cools off to what seems like well below how it was set. It makes me wonder on occasion if the propane is low or out, though I've noticed with the heat running more now that I'm in MD that the system won't kick on at all (fan and furnace or even just fan) if there is no propane.

Yes,, thats my issue, If I could reduce the amount of fan run on after the flame goes out it would retain the heat. Instead it feel like it is blowing off the heat generated.

[RavensFan24]

Mine works the same way. My wish is that the thermostat would show the ACTUAL temperature in addition to the set temperature. When the heat runs, I feel like it gets super hot (well over how it was set) and then it cools off to what seems like well below how it was set. It makes me wonder on occasion if the propane is low or out, though I've noticed with the heat running more now that I'm in MD that the system won't kick on at all (fan and furnace or even just fan) if there is no propane.