25 replies to this topic

[Wallowa]

Thanks for the reply! I'm pretty certain this was the issue. I'm glad to know there is a work around. It would be totally ridiculous if these furnaces were obsolete at low temps and/or elevation. 

 

 

Counter point...the furnace in my 2016 Hawk, unmodified, has worked perfectly at -15 F and at 9,800 ABSL....of course we are only a sample of 1.

[Mthomas]

Counter point...the furnace in my 2016 Hawk, unmodified, has worked perfectly at -15 F and at 9,800 ABSL....of course we are only a sample of 1.

Scame here, 2018 hawk up to 10,300 ft but not so cold and I replaced the analog thermostat with a digital. Key is lithium batteries which will continue to operate properly at low temps. N=2

 

I think that the design of the low amperage model heater, which is already operating at a minimal airflow to keep amp usage low, does not allow for even a tiny restriction of the airflow. I think some of the campers are assembled with just enough of an offset from the heater to the register that there is a bit more air restriction in the duct and …no heat at lowered air density, or low voltage in batteries. Either way, not enough flow and sail switch cuts it off.

Edited by Mthomas, 13 October 2022 - 09:32 PM.

[AWG_Pics]

Counter point...the furnace in my 2016 Hawk, unmodified, has worked perfectly at -15 F and at 9,800 ABSL....of course we are only a sample of 1.

 

Knock on wood, but we have had no issues with our 2019 Hawk furnace. Have camped at over 8,000 feet several times at over 9,000 at least once.

[Weissenheimer]

I have to say I believe it is more an issue of a dirty sail switch and less about the resistance from the 3" of ducting and slight bend (lmfao).  Mthomas may be right about these heaters running at the "bare minimum" to activate the sail switch, but how come my heater kept working even at 11.7 volts (batteries were toast) with the ducting installed?  I have still had my heat fail at 12.8v with new batteries too.  Every time it does fail (twice a season maybe).  I take apart the switch and find "belly button lint" in there. It appears to be just enough to prevent the microswitch from activating. I don't have any pets, this lint is just what you get with a recirculating system in a small space.  Although a better switch design could prevent this and I believe there is one out there P/N 33081 or something.  Sometimes I have to fully take apart the sail switch but I have it down to 5 minutes and the heat always comes back without fail.  Mind you I am at sea level so maybe this is a case of stacking deficiencies and not always one single thing

[IDPaddler]

I have to say I believe it is more an issue of a dirty sail switch and less about the resistance from the 3" of ducting and slight bend (lmfao).  Mthomas may be right about these heaters running at the "bare minimum" to activate the sail switch, but how come my heater kept working even at 11.7 volts (batteries were toast) with the ducting installed?  I have still had my heat fail at 12.8v with new batteries too.  Every time it does fail (twice a season maybe).  I take apart the switch and find "belly button lint" in there. It appears to be just enough to prevent the microswitch from activating. I don't have any pets, this lint is just what you get with a recirculating system in a small space.  Although a better switch design could prevent this and I believe there is one out there P/N 33081 or something.  Sometimes I have to fully take apart the sail switch but I have it down to 5 minutes and the heat always comes back without fail.  Mind you I am at sea level so maybe this is a case of stacking deficiencies and not always one single thing

 

I'm inclined to think if it was lint in the sail switch it wouldn't come back on until cleaned. My heater failed at elevation (7-9.5K ft) and low 30 degree temps. It fired right back up when I dropped back down to 2800 and warm temps. Hasn't failed since. 

 

I'm going out this weekend. Weather is gonna turn wintery in the high country. Might just make a side trip up to ~7600 for the night and see what happens. Bringing a Mr. Buddy just cause I can! 

[Wallowa]

Concur...from what I have read the "improved' sail switch is the same as the old one but with a different base mount [82 vs 81]....hence, it seems logical to assume that debris [belly button lint  :rolleyes: ] inhibits the sail switch movement thus it does not make electrical connection and start ignition of furnace.  Lower elevations have higher air density and perhaps that increase air mass will move a slightly compromised [clogged] sail switch....

 

Has anyone actually taken out a sail switch that "failed" to start a furnace and confirmed that the circuit [electrical contact] was defective therefore stopping the electrical furnace starting signal?

Edited by Wallowa, 20 October 2022 - 03:25 PM.

[pvstoy]

Interesting thought that somebody can try... Has anyone hot wired the switch to tell the heater computer that the air flow is working and light the burner? Like the thermostat you can bridge the wires to get the heater to run, then un-bridge the wires to stop the heater. Timing for bridging the sail switch wires may be more critical and disconnecting them.

 

I guess that would be a way to get heat if it is the sail switch that failed to see if it would work by you being the switch. Hey if that did not fix it then you might have other problems associated with the heater.

Edited by pvstoy, 21 October 2022 - 02:06 AM.

[Jsoboti]

I had the same issue, removing the ducting only worked somewhat. The ultimate fix for me was to simply remove the plastic disk on the very front of the furnace that swivels and diverts air to the sides.

 

Simple to do and my furnace works 4.0 at 8,500 feet where I usually camp in the winter. Hope this helps!

[IDPaddler]

I had the same issue, removing the ducting only worked somewhat. The ultimate fix for me was to simply remove the plastic disk on the very front of the furnace that swivels and diverts air to the sides.

 

Simple to do and my furnace works 4.0 at 8,500 feet where I usually camp in the winter. Hope this helps!THanks 

Thanks for the post. I'll try that first if/when it fails again.

 

Well I was out for 3 nights with last night down the mid 30's and snow line less than 1000ft up. Furnace worked like a champ, albeit only 1800 ft or so. 

 

Untitled by cory shuler, on Flickr

[Weissenheimer]

Interesting thought that somebody can try... Has anyone hot wired the switch to tell the heater computer that the air flow is working and light the burner? Like the thermostat you can bridge the wires to get the heater to run, then un-bridge the wires to stop the heater. Timing for bridging the sail switch wires may be more critical and disconnecting them.

 

I guess that would be a way to get heat if it is the sail switch that failed to see if it would work by you being the switch. Hey if that did not fix it then you might have other problems associated with the heater.

 

I do believe someone mentioned this before in another forum and they said the furnace is smart enough to not allow this type of hack.  The furnace will refuse to light if that switch is already closed before the blower starts spinning, it knows something is up.  But it makes me wonder if a hard wire switch could be manually activated a couple seconds after the blower kicks on, and that would successfully trick it? However you'd have to manually attend your furnace every time it wants to kick back on lol.