Heater

[5 Spotter]

I have a '03 Grandby with a Suburban heater. My heater will sometimes light, but not consistently. It's more likely to light in the comfort of my garage than it will when I'm in snow. It's also more likely to light when I have my camper plugged into house current or when the truck's motor is running. I am frequently successful with ignition if I slightly pull the sail switch with a piece of wire- but not always. I wish I had easier access to said switch for possible lubrication. I have a newer auxillary battery and my propane tank shows about 1/2 full. The fan always comes on but the Piezo usually fails to click. I think I've read most of the posts here regarding possible issues and have blown out the unit from both sides with compressed air. Any suggestions would be greatly appreciated. Thanks, 5 Spotter

 

[n0izh]

When we bought our camper the furnace was kinda intermittent. I found some loose and corroded connections on furnace. That would be the first and easiest place to start. Make sure all the spade connectors are clean and fit tight. Very slightly squeeze the female side with some needle nose pliers if they seem to be loose. You should also check the propane orifice to be certain a spider hasn't partially blocked things with a web. Any trouble with the stove that might indicate a regulator problem? Also starting from the battery check the voltage and connections for anything that isn't solid. Make sure the battery terminals are clean and shiny. Check the voltage on the battery itself, then on the terminal...they should be the same for a good connection. Your post made it seem to me as though the voltage the furnace is seeing may be low. The battery voltage should be the same as the voltage at the furnace minus a few tenths due to wire resistance. Finally, is the battery really charged?
Happy holidays!

John

 

[Desert Rancher]

It's also more likely to light when I have my camper plugged into house current or when the truck's motor is running.


That right there indicates a low voltage situation (truck running puts out about 14.5 volts). Always keep in mind, you only have 12 volts to play with and then it drops off quickly as you turn things on or the battery wears down.

Get a DVM and start measuring your voltage. Start at the source (the battery) and at various places downstream. Start turning things on and watch the volts drop. Around 11.5 volts, things start to not work and it drops off real soon.

Bad connections, bad crimps and especially poor ground connections will cause enough of a voltage drop to make things fail.

(Every wire connection in my camper, including the additions in my truck are hard lug crimped, soldered and shrink sleeved.)

Again, a cheap DVM will help you chase down those low volt problems.

Let us know if more help is needed, but that doesn't mean I know much - just sayin'...

 

[UglyScout]

I am frequently successful with ignition if I slightly pull the sail switch with a piece of wire- but not always.


This also sounds like a low voltage issue. If the fan can't spin fast enough to activate the sail switch it will not fire the 'fire'.

Do some voltage checks and see what they say.

 

[5 Spotter]

Thanks for the responses Ugly Scout, Desert Rancher, and N0IZh. I will get a volt meter and try to access the connections on the heater and the propane orifice. It looks like work just to access those connections. I'll need to remove the cabinet face. To do that I'll need to disconnect the thermostat, a regular duplex outlet, a 12 volt DC socket connection, and the battery/ water tank monitor. I'll report back. Thanks again. 5 Spotter

 

[Stan@FourWheel]

We had quite a few customers with the same problem as you.

We stopped using that Suburban furnace for that reason.

We are now using an Atwood furnace and they seem to be working great.

I think the sail switch (small wetaher vain looking thing in the back) is just too small or the fan in the furnace is under powered on that Suburban furnace.



If the customer had the truck running or the camper plugged in to shore power, the fan was running at full speed and would easily trip the sail switch and the furnace would light right up.

But if they were parked, the furnace fan would run significantly slower and not trip the sail switch. The furnace would cycle on, but would never light.

I have heard back from customers over the years that tried to open up more air flow to the furnace, and it did help in some cases.

This could be as simple as just removing the grill on the front of the furnace before trying to start it, or looking at the cabinets surrouding the furnace (in the front & inside the cabinets) and maybe drilling some small holes to allow more air flow inside the ccabinet, behind the furnace, to allow the fan to run a bit easier.

We had a couple of customers take their campers in to RV centers where they found an "old timer" working there that had some common sense. He added a very small piece of insulation tape to the end of the sail switch (so it would catch more air and move farther with less air blowing on it). This seemed to work well. BUT, I'm not sure safety wise this is the best thing. That would be at your own risk sort of thing. The sail switch does serve a safety purpose. If there is not enough air flow through the burner tube, the furnace will shut off. This is in place to keep the furnce from potentially over heating.

Take a look, poke around in there, and see if you can open it up a little so it gets more air.

DD, this might be part of your furnace mystery as well ?

Hope this helps.


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[MarkBC]

We had quite a few customers with the same problem as you.

We stopped using that Suburban furnace for that reason.


Stan-
I hadn't heard this before -- useful information that may answer several posts with this symptom. This explanation fits with my experience where the igniter won't fire if the battery is a little low but will if I start the truck engine (which boosts the battery).
You mentioned the sail switch "in the back". Does this mean it's on the outer-wall end of the furnace, so the furnace needs to be removed to access the sail switch?

 

[craig333]

All good advice. I use these type of connectors to ensure a good connection. I no longer use any connectors that don't have heat shrink.

Cost a bit more but worth it.

Don't forget the grounds. Often they are grounded through the frame, sheet metal etc. These can get corroded, paint wasn't removed or other poor connections. If they look good sometimes you just need to add an additional ground wire.

Also check your charging system. It can be charging enough to start the vehicle but still not the full voltage the heater wants.

These things are pita but I hesitate to put the full blame on the heater. I mean look what we put them through, dust, dirts, spiders, altitude changes, extreme vibration. Its a wonder they do as well as they considering.

 

[Stan@FourWheel]

I'm not sure if the furnace has to come out, or not, to get to the sail switch ??

You might be able to get to it from the front, but it is located in the back of the furnace and there is not much working room inside of there.



I guess you could take grate off of the front of the furnace and see if you can get your hand down the triangular tube? I just don't know how strong that sail switch is ? It looks pretty delicate.


see attached pictures ...


.

 

[Stan@FourWheel]

more pictures ...



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[MarkBC]

Thanks, Stan.

 

[Stan@FourWheel]

We thought about bypassing the switch, but it just sounded too risky.

It might be REALLY dangerous not to have the sail switch functioning somewhat normally.

The sail switch does serve a very good purpose.

I just wish it wasn't so sensitive on that Suburban furnace.

We would NOT want your camper to end up like this ...




Note: this camper was NOT burnt up by the furnace. Some jerks broke in to his camper, stole some items out of it, and then to top it all off they set it on fire as they left. Nice people, eh? Grrrrr



But he had insurance and they covered some of the new camper cost.

Thought I would post just for the heck of it.

It gives you guys a chance to see all the wierd things we get to see here week to week.

Don't forget to keep your fire extinguisher in the camper !

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[5 Spotter]

Thanks Stan and others for your informed replies.

I removed the cabinet face to reveal the heater. It appears identical to the posted pics.

The sail switch is located on the outer wall-end of the furnace and is not much more accessable with the cabinet face removed. I can see it more clearly now though. It is delicate and there's not much to lube even if I did completely removed the heater from the cabinet.

I already have a 2" x 3" hole in the cabinet divider wall that allows easy airflow and is located very close to the sail switch. For better airflow I'll need to open the adjacent cabinet door though.

I have tinkered with all connections and removed and checked a fuse located on a wire going into the heater. I cleaned the fuse terminals.

For some reason, and I wish I knew why, the heater has consistently fired-up every time I've tried it now that everything is exposed. It must be improved airflow or an improved electical connection. I can clearly hear that the fan is running at higher rpm's, which in turn easily pushes the sail switch far enough to activate the Piezo. And that's with the auxillary battery- just the way it should.

 

[craig333]

Fire extinguisher(s) for me. I'm amazed it didnt burn to the ground. That just makes me shudder.

 

[5 Spotter]

I thought I would post conclusions from my recent attempt at repairing, or at least improving the performance, of my Suburban heater.

Does anyone have this same unit (model DD-17DSI) that works consistently with auxillery battery?

When I removed the cabinet face, exposing both the heater and the interior of my propane tank enclosure, the heater worked flawlessly and with greatly improved vigor every time I tried to lite it. In fact, the sail switch worked so well that it actually moved all the way to its limit and was in contact with the back of the heater enclosure.

The interior of this cabinet space is nearly completly enclosed. Although cabinet partitions on either side of this space have small openings where various wires travel, the heater, fan, and sail switch must operate in an area that is fairly airtight. One partition has a small opening that is near an exterior vent that is behind my refrigerator and the other small opening draws limited air from an enclosed cabinet.

I think this model simply needs a greater fresh air supply to operate correctly on auxillery battery.

I cut a 2" hole with a hole saw in a cantilevered and unnoticable part of my cabinet face in an attempt to allow impoved airflow into the heater area. I cut the hole the same size as available grommets in case I needed to close the opening.

It wasn't enough. Even though the new opening helped, the heater still doesn't fire consistently after I buttoned everything up. Lots of air gets drawn into the newly cut hole when I get the unit lit. I can feel it easily with a bare hand and an open flame sucks obviously into the hole even from some distance.

Think I need a better heater.

5 Spotter

 

[leadsled9]

I use these type of connectors to ensure a good connection. I no longer use any connectors that don't have heat shrink.

Cost a bit more but worth it.


craig333,

How do you melt the enclosed solder on these? Is the "enclosed solder" area covered with the heat shrink? Where do you buy these?

 

[craig333]

I buy them from mcmaster-carr http://www.mcmaster....rminals/=a8hgos
I use the model V heat gun with a little u shaped attachment so the heat goes all around. Takes about ten seconds or so for the solder to melt. Wish they had the solder option all the heat shrink terminals.
http://www.mcmaster....at-guns/=a8hkcz
Hmmm, trouble with links, its on catalog page 2719. Look for light duty heat guns.

 

[leadsled9]

I buy them from mcmaster-carr http://www.mcmaster....rminals/=a8hgos
I use the model V heat gun with a little u shaped attachment so the heat goes all around. Takes about ten seconds or so for the solder to melt. Wish they had the solder option all the heat shrink terminals.
http://www.mcmaster....at-guns/=a8hkcz
Hmmm, trouble with links, its on catalog page 2719. Look for light duty heat guns.


I have a great 1200 watt heat gun with the u shaped attachment....but I've never delt with solder that melted at that low amount of temperature. I always had to use a soldering iron.

I take it these connectors go on just like regular heat shrink then....is that correct? And the solder melts at that low temp and all is good???