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Furnace Removal


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I have a Suburban DD17dsi furnace in my 1993 Itasca Spirit. I would like to remove it but it seems to be stuck and will not slide out.I assumed the exhaust vent is a slip connection and there are only 2 wood screws anchoring the unit to the sub floor at the front.The gas and electrical connections are also in front, so it shoild just slip out of the cabinet cavity right?

Help!! I want to store a ventless  propane heater connected by a hose with a quick connect to the existing flare fitting and keep it in that spot with a hinged door for access.

Edited by Jeffrey Burger
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I am aware of the ventilation requirements. The exhaust vent hole will be open as additonal air for the heater along with an open window.

The heater lights and then the flame jumps off the burner and goes out within a few seconds.This cycle continues  endlessly until the thermostat is turned off. I suspect it is  combustion air restriction, but I still need to remove the exhaust vent and or furnace to see if there is a restriction.

Thank-you for the warning though Linda!

By the way, the efficiency of a ventless heater compared with the original is such that it offsets the loss through a window and doesn't use 12v power from the coach battery.

Edited by Jeffrey Burger
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Thank-you Linda. I have the original installation/owner's manual that has good detail but doesn't show if the exhaust vent is just a slip fit or is solidly connected to the furnace.The unit does move a little sideways so if it was rusted together I would have been able to break it loose.

Thank-you for helping though...you are awesome!

 

Jeff

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Looks to me like you need to pull the vent cap off from the outside after you remove the screws. There is caulk in there so it will probably need some prying to get it off. Bet that's what's locking the furnace in place. Might not be the diagram for yours but they all show screws holding them on

Linda S

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Well it seems that the unit does just slide out if it isn't stuck because of a bent edge of sheet metal!!! There is this amazing new device that I found called a "flash light"...amazing!

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22 minutes ago, Jeffrey Burger said:

Well it seems that the unit does just slide out if it isn't stuck because of a bent edge of sheet metal!!! There is this amazing new device that I found called a "flash light"...amazing!

He's seen the light!

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I have one out - all that was holding mine in was 2 screws at the front going into the floor and the gas line.  The vent just pulls off.

From what you are describing, I bet that furnace will work, but needs to be run.  IF you are at a higher altitude the flame should settle down after it warms up.

You can check for obstruction by putting your hands over the intake/exhaust vent.  

It will not run without a good source of 12v dc power. You can use external power or start your engine, either will produce strong dc power.  Your cabin battery should be enough - if it is fully charged, etc.  The gas valve and igniters require dc voltage as well as the fan. 

 

Note that the auto start function will try 3 times then the fan just runs and runs.  If you turn it off, wait a little bit and turn it on you get 3 more tries. 

 

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Remove the screws around the exhaust port on the outside it was a way to hold the furnace tight to the exhaust port some were some were not but if it does not move that maybe you answer.

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Thanks for the comments...to explain exactly what the furnace does is it ignites and establishes the flame then after about 3 to 5 seconds the flame lifts off the burner as if the pressure is too high and blows out. The furnace will do this repeatedly until it is turned off. The flame looks nice and blue, taking the cover and gasket off allows the flame to last just a little longer prompting me to pull the furnace (which I finally was able to do) to see if there was a combustion air problem. There is a squirrel cage fan that rotates on the same spindle as the blower and is fine. All looks clean the LP pressure looks good because the water heater burner is normal and the stove and oven flames are perfect. I think the problem is in the circuit board. No one seems to have experienced this symptom so I have not found an answer.

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Dinosaur boards. Match your's up to the pictures inline. They are the only ones that try to light 3 times the original one only try once. Yours  is a unusual problem the replacement board is a good up grade regardless if it fixes your problem or not I'm not one to replace parts but that would be some thing I would try.

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  • 1 year later...

I'm having the same problem with my 1991 Toyota Itasca IT 321 RV spirit. I can't get the Suburban heater out. I got the 2 screws outside on the exhaust out completely, two screws inside on floor are removed, gas line is disconnected.

update:      I finally got the furnace out, repaired it and it's working beautifully. To get it out I needed to remove on the outside the exhaust flange and tube that goes into my rv which is only about a foot long.

Then I realized also the cabinet was pressing down (where the drawers slide in & out) on the top of the furnace keeping it tightly bound  even though the 2 screws  had been removed.(holding the furn. in place) So once I tapped the cabinet crossmember upward away from the furnace relieving the pressure I was able to pull the furnace out.

I found the sail switch to be the problem because it wasn't sensitive enough to be activated when the voltage dropped a little bit on the battery(fan not generating enough wind), before it would not work properly if the voltage was down below 12 volts. Now it works when the voltage drops down to even 10.5 volts.

 I also noticed the fan would bind when I turned it by hand for about maybe one quarter of its full turn and it was because they had tightened one of the screws that mounted the fan in the housing too much at the time it was manufactured.....so I've always had this challenge now going on 25 plus years. This unit now works better than it ever did once I relieved the screw pressure so that the blade of the fan can turn freely (meaning the fan can turn faster helping to actuate the sail switch.)

 They wanted to charge me $100 plus an hour to troubleshoot this furnace and I thought it was crazy since it was intermittent and would have taken countless hours of troubleshooting..... I would have gone broke....the guy would have wound up owning my RV by the time he figured it out.?

Edited by rogersvensson
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They get stuck sometimes in the exhaust flanges sounds like you got all the parts loose.

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  • 1 month later...
  • 2 months later...

On our '91 Warrior, the two screws that hold the outside end of the exhaust tube to the external flange are not accessible. The space between the inner part of the flange and the outer is too narrow for even an offset screwdriver and with those screws in place the flange can't be pulled off. With the two screws that anchor the unit to the floor removed, the heater feels like it's free to be pulled out but is held at the outside end of that tube. Is there a slip connection somewhere between the heater and the exhaust port?

The heater's issue, btw, is that after the blower starts and the the igniter sparks, the gas valve doesn't open. It cycles through the three auto-start attempts and the spark is visible each time, but (though the tank is full and the stove burners produce flame) the gas valve doesn't open.

Though I've tried it both ways, I assume that the open position for the gas shut  off handle is in line with it's outlet, and the position of the handle shown in the photo is the off position?

40325459_239551076908266_918546187236147200_n.jpg

40204876_284241472190731_7897502047598018560_n.jpg

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Looks to me there are two screws in your picture that are holding it to the floor. I also believe you need to remove the exterior screws where the exhaust flange is.

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15 minutes ago, Maineah said:

Looks to me there are two screws in your picture that are holding it to the floor. I also believe you need to remove the exterior screws where the exhaust flange is.

agreed, and you'll need to disconnect hard gas lines if removing completely.  Make sure main propane shut off valve is 100% closed.  

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12 hours ago, Maineah said:

Looks to me there are two screws in your picture that are holding it to the floor. I also believe you need to remove the exterior screws where the exhaust flange is.

Thanks, Maineah. I took the photos before I removed the screws you mentioned. With the floor screws out and the flange screws out,  it still feels anchored to the outside. It will move slightly from side to side, with the pivot point at the wall. With the four flange screws removed, the flange is still anchored to the exhaust tube by the two screws that I can't get a screwdriver into, as they are recessed into the inner part of the flange.

Thank you, Anthony for that excellent safety advice. 

Edited by Warrior-warrior
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The vent is coaxial the center is the exhaust outlet the outside allows in makeup air it fits in fairly tightly to the firebox it may take some effort to get it free see if you can remove the exhaust fitting first.

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On 4/9/2018 at 12:47 PM, rogersvensson said:

I found the sail switch to be the problem because it wasn't sensitive enough to be activated when the voltage dropped a little bit on the battery(fan not generating enough wind), before it would not work properly if the voltage was down below 12 volts. Now it works when the voltage drops down to even 10.5 volts.

 I also noticed the fan would bind when I turned it by hand for about maybe one quarter of its full turn and it was because they had tightened one of the screws that mounted the fan in the housing too much at the time it was manufactured.....so I've always had this challenge now going on 25 plus years. This unit now works better than it ever did once I relieved the screw pressure so that the blade of the fan can turn freely (meaning the fan can turn faster helping to actuate the sail switch.)

Just as reference (A reading of 12.65-12.77 volts means your battery has a full charge. 12.45-12.54 volts means you have a 75% charge, 12.24-12.29 is 50% charged, and 11.99-12.06 volts is 25% charged. 11.75-11.89 volts means your battery is dead.) I bring this up because fan rpm might be too low at low voltages to properly cool the combustion chamber. https://www.yourmechanic.com/article/how-to-check-the-voltage-of-a-car-battery 

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  • 1 month later...

Darrel! Thank you, Dude. You found us in the Freddy's parking lot and, not only did you know everything about our furnace, but you invited us home to look at the one you had stored in your garage. You gave us a place to camp for the night, fed us an awesome breakfast, and spent hours helping us troubleshoot the furnace.

You are the best! Best regards to you and the missus. We won't forget you!

 

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Had a good time myself.  Darrel

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