65 replies to this topic

[ri-f]

There has been plenty of discussion on sail switches for the Dometic furnaces that were having trouble with igniting and staying lit. I just bought a spare sail switch w/bracket for mine (I wasn't having a problem, but simply wanted a backup): Mine is Dometic model DFSAD12111 (installed in a 2020 Hawk shell). My furnace has serial number 94486978 (your serial number is used by Dometic to determine the correct sail switch and bracket required for any particular furnace). Dometic told me today that they had problems with some of their sail switches and they upgraded the switch. The original OEM sail switch model number for mine was #33082 (which is what FWC says they keep in stock for replacements. repairs, etc). But Dometic says that those were problematic switches and they recommend not using those, but instead using model #33081, because it was redesigned to work correctly. This may or may not be the correct sail switch for your particular Dometic 12,000 BTU furnace, you can only confirm this with your model number and serial number and a call to Dometic support for any upgrades they may have available for your particular furnace. It could make a difference in your furnace's performance (or lack thereof). Just a heads up for anyone who might be concerned.

 

Rich

[Lee Murian]

Thanks for this information. As the owner of a 2020 Hawk that had furnace issues, I'm going to check my unit but as the same model year, I would suspect same furnace. I've had my camper off for the winter and am planning to install this week. Would be good to know if there is a solution.

[JWL]

It begs the question why FWC doesn’t send the defective ones back to Dometic and get the current ones??

I guess because it’s the same reason why they can’t come up with a fix for the bad vent design in the Hawks. Which so far is the only issue I have had with my furnace. But this is good to know for when this happens.

[Wallowa]

It begs the question why FWC doesn’t send the defective ones back to Dometic and get the current ones??

I guess because it’s the same reason why they can’t come up with a fix for the bad vent design in the Hawks. Which so far is the only issue I have had with my furnace. But this is good to know for when this happens.

 

 

Bad vent design in Hawk?  I missed that; what are the details.

[ri-f]

Bad vent design in Hawk?  I missed that; what are the details.

I believe that reference is to the vent cover, which is offset to the duct behind it, creating a slight bend in the duct and narrowing the opening. This may restrict full air flow and that may prevent the burner from staying lit. This has been reported as a problem. If this happens, the solution is to unscrew the furnace cover, on the inside of the camper, and un-kink the duct (or shorten the duct length so it can't bunch up and restrict the air flow). This hasn't happened to me, but it has happened to others.

[JWL]

I believe that reference is to the vent cover, which is offset to the duct behind it, creating a slight bend in the duct and narrowing the opening. This may restrict full air flow and that may prevent the burner from staying lit. This has been reported as a problem. If this happens, the solution is to unscrew the furnace cover, on the inside of the camper, and un-kink the duct (or shorten the duct length so it can't bunch up and restrict the air flow). This hasn't happened to me, but it has happened to others.

Yes that’s it. FWC came out with a vent cover that has the duct opening off center so it is in line more with the furnace opening. After scrunching, shortening etc. the duct on mine to no avail I tried to get this “new and improved “ face plate and was told that it didn’t work either. The new “fix” is to just remove the duct. That works but I feel a lot of the heat stays in the furnace box. Not very efficient…

[Wallowa]

Yes that’s it. FWC came out with a vent cover that has the duct opening off center so it is in line more with the furnace opening. After scrunching, shortening etc. the duct on mine to no avail I tried to get this “new and improved “ face plate and was told that it didn’t work either. The new “fix” is to just remove the duct. That works but I feel a lot of the heat stays in the furnace box. Not very efficient…

 

 

Thanks for this...can you explain what exactly "didn't work"?  Did the flex tubing kink and you could see this through the plastic plate over the outlet inside the camper?  What went wrong with the furnace; back pressure that shut the furnace down??  Need to understand to monitor mine.

 

Also does the model of FWC change the furnace ducting?  And side vs front dinette? 

 

Thanks again...

[JWL]

Thanks for this...can you explain what exactly "didn't work"?  Did the flex tubing kink and you could see this through the plastic plate over the outlet inside the camper?  What went wrong with the furnace; back pressure that shut the furnace down??  Need to understand to monitor mine.

 

Also does the model of FWC change the furnace ducting?  And side vs front dinette? 

 

Thanks again...

I’m not sure about other models, I know it is primarily in Hawk Shells so I don’t know why the other Hawk layouts would be any different.

The furnace opening sits on the right side of the cabinet and the faceplate opening is in the center. So in about 3 inches of space the flexible duct has to go from right to center and allow for the bends to make the connection. All of which restrictions airflow enough to not all the furnace to start.

Here are some pics

The one with the vent was after shortening as much as I could and still get my hands in to attach, it still didn’t work.

 

Attached Thumbnails

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[ri-f]

14E10DA0-AB27-4E38-836A-1FEAE94B2774.jpeg

I’m not sure about other models, I know it is primarily in Hawk Shells so I don’t know why the other Hawk layouts would be any different.

The furnace opening sits on the right side of the cabinet and the faceplate opening is in the center. So in about 3 inches of space the flexible duct has to go from right to center and allow for the bends to make the connection. All of which restrictions airflow enough to not all the furnace to start.

Here are some pics

The one with the vent was after shortening as much as I could and still get my hands in to attach, it still didn’t work.

JWL - Are you certain that the vent offset is the primary problem? Does removing the flexible duct always solve the problem of the furnace not staying lit or is it hit and miss? You've tried swapping out the sail switch kit? The only other thing I can think of that might cause the burner to not stay lit, assuming all the electronics are OK (circuit board, etc,) is the igniter gap being too narrow. The gap is supposed to be 1/8" but some have reported success with a wider gap of say 1/4". And lastly, if you turn the knob on the propane tank valve too quickly when you first try to start up the furnace it could also cause an issue with the igniter not working. Try turning the valve on very slowly. If it really is just the vent, then the only other suggestion might be to possibly make your own vent face plate so that it is positioned properly for full air flow. Maybe attach a fixed, short, sheet metal duct, like a stove pipe so it can't bend and kink up, and run it directing to a new face plate with a rotating vent that you could buy and insert in the face plate directly in front of the new sheet metal duct. Just a thought. Rich

Edited by ri-f, 14 May 2021 - 05:48 PM.

[DarinH]

It begs the question why FWC doesn’t send the defective ones back to Dometic and get the current ones??

As recent as late March, they apparently haven't. I picked up my 2021 Grandby in late March and slept in it the first night on shore power, in Montana, and the heater worked like it should. 2 weeks later I'm camping off grid in northern Utah, and the heater would not stay lit for more than a few minutes with fan running on a fully charged battery. When I would have the truck idling, it would stay lit, but I'm not going to idle my truck all night. Good thing I had a warm sleeping bag those 2 nights.