# Furnace Heat Slowly Blows Through Vent



## Ostenhouse

Hello,
I am the proud new owner of a 2004 21rs. We are very excited about camping this year (especially my 4 year old).

I have the coach sitting in the driveway. I have fired up the furnace several times to spend time out there and have been dissapointed with the heater.

The furnace seems to run normally but the hot air just barely blows up through the vents. Is that normal??

Best Regards,
Gary


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## john7349

On my 2008 21RS, the vent by the slide out blows about 80% of the hot air. The rest through the other two vents....


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## OutbackPM

john7349 said:


> On my 2008 21RS, the vent by the slide out blows about 80% of the hot air. The rest through the other two vents....


 On my 26RS the one nearest the rear slide did the same thing. I put variable vents in to improve the distribution.

If your total flow is low in all the vents then look for a blockage in the vent.

On my new camper I had a similar thing except the furnace would cycle off early. I found the back of the furnace had only 1 screw in it so leaked internally all the air. Once secured it would run longer and blow much more.


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## Calvin&Hobbes

I found that one of my vents barley blew any air through it...When I did my spring cleaning, I pulled all the vents and vacuumed the insides of the duct work- and the vacuum grabbed a big slug of insulation and aluminum taped all balled up. Gilligan couldn't get to the trash can, so he shoved it down the duct work. Blows like a hurricane now.


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## California Jim

Back in the early days of this website this topic was often discussed. Particularly on your model year. At the time there were several who discovered that the aluminum ducting had been pinched down for various reasons. You might want to consider removing your vents and using an inspection mirror to see what's happening in there. Hopefully it's just simple debris as noted. Good luck.


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## Ostenhouse

Calvin&Hobbes said:


> I found that one of my vents barley blew any air through it...When I did my spring cleaning, I pulled all the vents and vacuumed the insides of the duct work- and the vacuum grabbed a big slug of insulation and aluminum taped all balled up. Gilligan couldn't get to the trash can, so he shoved it down the duct work. Blows like a hurricane now.


Thanks for the great tips, Before i pull the bottom off the trailer to check out the ducts i am going to run a shop vac down each vent.

Gary


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## bbwb

I have an '08 23rs and the first time I put the heat on, I too thought that the air flow was wimpy at best. I have cleaned the ducts and looked down them and found nothing. I will admit that the trailer heats up just fine...might be the way it's suppose to be









bbwb


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## johnp

I had an issue on one of my Outbacks the furnace is the same on all trailers and there is plugs in the side of the furnace that don't get used on the Outbacks they are for hose connections. Anyway the furnace wasn't blowing very well and when I removed the return vent to inspect the furnace two of the 3" plugs had fallen out. Put them back in and the air flow was forced back into the ductwork in the floor.

And yes there was problems on some of the early Outbacks the ducts were getting crushed by the fresh water tank and the front vents didn't blow very good.

John


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## Ostenhouse

johnp2000 said:


> I had an issue on one of my Outbacks the furnace is the same on all trailers and there is plugs in the side of the furnace that don't get used on the Outbacks they are for hose connections. Anyway the furnace wasn't blowing very well and when I removed the return vent to inspect the furnace two of the 3" plugs had fallen out. Put them back in and the air flow was forced back into the ductwork in the floor.
> 
> And yes there was problems on some of the early Outbacks the ducts were getting crushed by the fresh water tank and the front vents didn't blow very good.
> 
> John


I will check it out tonight and report back tomorrow.

Gary


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## Ostenhouse

Ostenhouse said:


> I had an issue on one of my Outbacks the furnace is the same on all trailers and there is plugs in the side of the furnace that don't get used on the Outbacks they are for hose connections. Anyway the furnace wasn't blowing very well and when I removed the return vent to inspect the furnace two of the 3" plugs had fallen out. Put them back in and the air flow was forced back into the ductwork in the floor.
> 
> And yes there was problems on some of the early Outbacks the ducts were getting crushed by the fresh water tank and the front vents didn't blow very good.
> 
> John


I will check it out tonight and report back tomorrow.

Gary
[/quote]

I took a mirror and looked down the ducts. The duct closest to the slide was almost pinched closed, it had a bout a half inch of clearance for air. The other two looked o.k. I pulled the vent and felt around the heater and felt a lot of air blowing out of seams. I am going to pick up a roll of alluminum duct tape tonight and seal it off as much as possible. I was not impressed with the craftsmanship of the person who built the plennum and duct work but whatever.

Gary


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## Nathan

Ostenhouse said:


> ... I was not impressed with the craftsmanship of the person who built the plennum and duct work but whatever.
> 
> Gary


We usually just refer to that person as Gilligan.


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## BoaterDan

To go in another direction, my vents never blow like a house one, and that heater blower seems to take a big hit from less than 100% battery charge.

But in practice the heater keeps us all toasty, and can run you right out of the end rooms.


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## ALASKA PFLOCK

Interesting? We have never had any issues with the trailer vents not blowing enough hot air. I like the idea of using a mirror to inspect the vents as well as adding house style vents.







I will try the mirror next time I vacuum out the vents.


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## California Jim

Ostenhouse said:


> I took a mirror and looked down the ducts. The duct closest to the slide was almost pinched closed, it had a bout a half inch of clearance for air. The other two looked o.k. I pulled the vent and felt around the heater and felt a lot of air blowing out of seams. I am going to pick up a roll of alluminum duct tape tonight and seal it off as much as possible. I was not impressed with the craftsmanship of the person who built the plennum and duct work but whatever.
> 
> Gary


Cool deal Gary. Sounds like you got it. As much as we love em', Outbacks have their share of grief too. Fortunately we have our gang here to help


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## john7349

john7349 said:


> On my 2008 21RS, the vent by the slide out blows about 80% of the hot air. The rest through the other two vents....


I guess I better check mine too!


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## BoaterDan

I've got a 10-15 foot run in both directions. I'm guessing you have to open up the belly cover to actually make any fix, eh?


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## CamperAndy

BoaterDan said:


> I've got a 10-15 foot run in both directions. I'm guessing you have to open up the belly cover to actually make any fix, eh?


Not always. Get a cheap kids air mattress and roll it up lengthwise. Use a thin flexible pole to push one end of the mattress down the duct. Once in place you inflate the mattress very slowly. This will reform the duct to a more or less open passage, it may be more round then square but that is better then flat.


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## Rob_G

CamperAndy said:


> Not always. Get a cheap kids air mattress and roll it up lengthwise. Use a thin flexible pole to push one end of the mattress down the duct. Once in place you inflate the mattress very slowly. This will reform the duct to a more or less open passage, it may be more round then square but that is better then flat.


American ingenuity at it's finest! Great solution!


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## BoaterDan

I looked down the vents with the mirror last weekend. Everything looks good, except for when I looked past the last vent. I couldn't tell if the run was really capped off or not because it was crushed in about 2 feet past the vent. I rigged up a block at the vent out of cardboard and duct tape, but that didn't really change the flow out of any of the vents.

I've never had a problem with the system heating the trailer, even in very cold weather, but listening to how loud that blower motor is compared to how little air is coming out the vents has me wondering again. Has anybody felt the movement that the motor is generating because you've had the heater out for repairs or something? I'm wondering if I might have an obstruction closer to the motor, and I can't see the part of the ductwork between the motor and the main run to the vents.


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## CamperAndy

They spend very little effort in sealing the ends of the ducting. It is just mashed flat and the end it rolled.

There have been a few people that have had low air flow and the reasons are typically due to the transition duct from the furnace to the duct that goes the length of the trailer has come loose or they did not cut hole in the floor or set the furnace in the correct location. Both issue require that you lift the furnace to inspect the interface and the transition duct.


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## OBcanOB

I've replaced the aluminum tape on ours, it started coming off and the plenum would fall down. I am interested in the inspection of the heater and it's parts. What is the easiest way to get in to it?

thanks,


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## BoaterDan

OBcanOB said:


> I've replaced the aluminum tape on ours, it started coming off and the plenum would fall down. I am interested in the inspection of the heater and it's parts. What is the easiest way to get in to it?
> 
> thanks,


My furnace is below my fridge, and there's a vented panel in the front. However, it looks like it must bolt through the floor. At least, I can't see anything holding it down from the top side.


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## russlg

I just fired up my heat for the first time. April 12 and it is freaking cold up here today!! The heat came on after I figured I had to push the reset button on the remote. It heats but like others have said, it has minimal airflow through the registers. I want to maximize what is flowing through them because I feel that any restriction creates a leakage of hot air. That leakage translates into a longer time required for the furnace to run to reach the desired temperature. That ends up wasting my precious propane!!

Looks like I am on a mission!


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## battalionchief3

I found a bunch of junk in my duct work. I have never put a mirror down their to see, may have to do that. I did take off the grill and looked around and it looked like it was sealed ok. We used it the last 5 days ( where is spring again??? ) and it heats up the camper well so I am not going to tear into it since it works well enough.


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## Nathan

CamperAndy said:


> I've got a 10-15 foot run in both directions. I'm guessing you have to open up the belly cover to actually make any fix, eh?


Not always. Get a cheap kids air mattress and roll it up lengthwise. Use a thin flexible pole to push one end of the mattress down the duct. Once in place you inflate the mattress very slowly. This will reform the duct to a more or less open passage, it may be more round then square but that is better then flat.
[/quote]
HVAC repair man or Heart Surgeon








I guess either fix the problem huh?


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## Calvin&Hobbes

Angioplasty of the heat duct...


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## BoaterDan

battalionchief3 said:


> I found a bunch of junk in my duct work. I have never put a mirror down their to see, may have to do that. I did take off the grill and looked around and it looked like it was sealed ok. We used it the last 5 days ( where is spring again??? ) and it heats up the camper well so I am not going to tear into it since it works well enough.


Yeah I agree. I don't think you could dry camp for long in weather in the 20s relying on the furnace anyway, and when we're plugged in it works fine to supplement the portable 110 heater we use.

It's more of a curiosity than a real issue for me at this point.


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## Just Add Dirt

i GOT A FUN ONE HERE.. I AM PROBABLY JUST IGNEANT.. BUT IS THE FAN IN THE HEATER (CARRIER) SUPPOSE TO RUN WHEN I GOT THE FURNACE ON AND TRYING TO HEAT THE JOINT WHILE ON BATTERY? CUZ WHEN I AM RUFFIN' IT THE FURNACE FAN DOES NOT BLOOOOOOWWW


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## john7349

The fan in the heater runs on 12 volts DC. It always runs off the battery, unless there are problems. Since your heater ignites, I would think the 12v fuse is OK. Does the fan ever run?


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## CamperAndy

Just Add Dirt said:


> i GOT A FUN ONE HERE.. I AM PROBABLY JUST IGNEANT.. BUT IS THE FAN IN THE HEATER (CARRIER) SUPPOSE TO RUN WHEN I GOT THE FURNACE ON AND TRYING TO HEAT THE JOINT WHILE ON BATTERY? CUZ WHEN I AM RUFFIN' IT THE FURNACE FAN DOES NOT BLOOOOOOWWW


As mention in the other thread you posted in the Carrier unit is for Air Conditioning and only works on shore power, it blows cold air from the ceiling vents. The furnace operates on 12 vdc, it blows hot air from the floor vents.

It would be easier to track the answers you get if you start your own thread and not post the same question in multiple threads. You may want to lose the Cap Locks also.


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## Just Add Dirt

CamperAndy said:


> i GOT A FUN ONE HERE.. I AM PROBABLY JUST IGNEANT.. BUT IS THE FAN IN THE HEATER (CARRIER) SUPPOSE TO RUN WHEN I GOT THE FURNACE ON AND TRYING TO HEAT THE JOINT WHILE ON BATTERY? CUZ WHEN I AM RUFFIN' IT THE FURNACE FAN DOES NOT BLOOOOOOWWW


As mention in the other thread you posted in the Carrier unit is for Air Conditioning and only works on shore power, it blows cold air from the ceiling vents. The furnace operates on 12 vdc, it blows hot air from the floor vents.

It would be easier to track the answers you get if you start your own thread and not post the same question in multiple threads. You may want to lose the Cap Locks also.
[/quote]
Actually the Carrier unit is the brains in the outfit, it controls the dometic furnace: Like I posted.. the fan on the furnace works fine while on 110VAC but when on battery, NADA, ziltch, no fan. 
Oh; I likes a little caps lock every once in a while, it helps me git release


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## CamperAndy

Just Add Dirt said:


> i GOT A FUN ONE HERE.. I AM PROBABLY JUST IGNEANT.. BUT IS THE FAN IN THE HEATER (CARRIER) SUPPOSE TO RUN WHEN I GOT THE FURNACE ON AND TRYING TO HEAT THE JOINT WHILE ON BATTERY? CUZ WHEN I AM RUFFIN' IT THE FURNACE FAN DOES NOT BLOOOOOOWWW


As mention in the other thread you posted in the Carrier unit is for Air Conditioning and only works on shore power, it blows cold air from the ceiling vents. The furnace operates on 12 vdc, it blows hot air from the floor vents.

It would be easier to track the answers you get if you start your own thread and not post the same question in multiple threads. You may want to lose the Cap Locks also.
[/quote]
Actually the Carrier unit is the brains in the outfit, it controls the dometic furnace: Like I posted.. the fan on the furnace works fine while on 110VAC but when on battery, NADA, ziltch, no fan. 
Oh; I likes a little caps lock every once in a while, it helps me git release








[/quote]

There are no shore power connections to either the Air conditioner unit or the Furnace that would affect the operation of the furnace. If your furnace is not working when not on shore power then you have a battery issue.


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## Just Add Dirt

CamperAndy said:


> i GOT A FUN ONE HERE.. I AM PROBABLY JUST IGNEANT.. BUT IS THE FAN IN THE HEATER (CARRIER) SUPPOSE TO RUN WHEN I GOT THE FURNACE ON AND TRYING TO HEAT THE JOINT WHILE ON BATTERY? CUZ WHEN I AM RUFFIN' IT THE FURNACE FAN DOES NOT BLOOOOOOWWW


As mention in the other thread you posted in the Carrier unit is for Air Conditioning and only works on shore power, it blows cold air from the ceiling vents. The furnace operates on 12 vdc, it blows hot air from the floor vents.

It would be easier to track the answers you get if you start your own thread and not post the same question in multiple threads. You may want to lose the Cap Locks also.
[/quote]
Actually the Carrier unit is the brains in the outfit, it controls the dometic furnace: Like I posted.. the fan on the furnace works fine while on 110VAC but when on battery, NADA, ziltch, no fan. 
Oh; I likes a little caps lock every once in a while, it helps me git release








[/quote]

There are no shore power connections to either the Air conditioner unit or the Furnace that would affect the operation of the furnace. If your furnace is not working when not on shore power then you have a battery issue.
[/quote]

Hey thanks there camper Andy!
I went out and disconnected the 110VAC from the camper and turned on the furnace and you are right; The fan does run on 12vdc but the airflow from the floor vents probably wouldn't blow out a match, however, when it is on 110VAC the airflow from the floor vents is 6 times stronger! this is a new to-me-from-the-dealer Outback with a new battery and a full charge. I can't figure this one.
Miffed


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## CamperAndy

The battery is not at full charge or one of the auto reset breakers is dieing and has a high resistance. Do you have a volt meter?


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## rdvholtwood

The vent closest to our bunks bairly blows any air - I will check out with a mirror and see if this is the case - other than that, the furnace works great and keeps the camper toasty. We were camping in VA this weekend and used it to take the chill from the dampness.


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## Just Add Dirt

CamperAndy said:


> The battery is not at full charge or one of the auto reset breakers is dieing and has a high resistance. Do you have a volt meter?


I do have a VOM meter... whats the plan?


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## CamperAndy

Just Add Dirt said:


> The battery is not at full charge or one of the auto reset breakers is dieing and has a high resistance. Do you have a volt meter?


I do have a VOM meter... whats the plan?
[/quote]

With shore power disconnected measure and record and post the following.

1 - Voltage at the batter with Everything turned off.
2 - Voltage at the converter terminals with everything turned off
3 - Voltage at the battery with the Furnace on
4 - Voltage at the converter terminals with the furnace on.

If you have more the .5 vdc difference between the battery and the converter terminals then check for voltage drop across the auto reset breakers (with the furnace running) that are mounted next to the battery. I suspect you will find there is a voltage drop there, check post to post and you should see 0 volts. if there is any voltage indicated it means the breaker is faulty.


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## forceten

I'm probably gonna kick myself for saying this, ....... but I'm an HVAC mechanic. Been one for 20 years before starting up my own oil company. Was an hvac instructor at penco tech also while going to college to help pay the bills.

Saying that, now I'm curious to see the quality of the work on my ductwork. Since I have to remove the bottom somewhat to drill into my garage I might as well remove a lot of it underneath and take a looks see. I also have snake cameras so I can take a look inside the ducktwork and see what things look like.


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## CamperAndy

forceten said:


> I'm probably gonna kick myself for saying this, ....... but I'm an HVAC mechanic. Been one for 20 years before starting up my own oil company. Was an hvac instructor at penco tech also while going to college to help pay the bills.
> 
> Saying that, now I'm curious to see the quality of the work on my ductwork. Since I have to remove the bottom somewhat to drill into my garage I might as well remove a lot of it underneath and take a looks see. I also have snake cameras so I can take a look inside the ducktwork and see what things look like.


You will not see the duct work from the bottom. There is a 4" floor structure that has a bottom and top lining that is also insulated. This floor structure is bolted to the frame. The snake will be helpful but do not cringe too much when you see how they closed the ends of the duct.


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## tdvffjohn

Not sure you really want to look


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## forceten

The didnt use end caps???


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## CamperAndy

forceten said:


> The didnt use end caps???


That is funny. Why use an end cap when you can step on it then tape the end shut.


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## Oregon_Camper

CamperAndy said:


> The didnt use end caps???


That is funny. Why use an end cap when you can step on it then tape the end shut.
[/quote]

OMG!!!!! Are you kidding? That is how they do it?


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## CamperAndy

Oregon_Camper said:


> The didnt use end caps???


That is funny. Why use an end cap when you can step on it then tape the end shut.
[/quote]

OMG!!!!! Are you kidding? That is how they do it?
[/quote]

Not kidding.


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## BoaterDan

CamperAndy said:


> The didnt use end caps???


That is funny. Why use an end cap when you can step on it then tape the end shut.
[/quote]

OMG!!!!! Are you kidding? That is how they do it?
[/quote]

Not kidding.
[/quote]

I've seen it with my own eyes too. Had to look and look cuz I was sure I wasn't seeing what it looked like I was seeing.


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## BoaterDan

CamperAndy said:


> The battery is not at full charge or one of the auto reset breakers is dieing and has a high resistance. Do you have a volt meter?


I do have a VOM meter... whats the plan?
[/quote]

With shore power disconnected measure and record and post the following.

1 - Voltage at the batter with Everything turned off.
2 - Voltage at the converter terminals with everything turned off
3 - Voltage at the battery with the Furnace on
4 - Voltage at the converter terminals with the furnace on.

If you have more the .5 vdc difference between the battery and the converter terminals then check for voltage drop across the auto reset breakers (with the furnace running) that are mounted next to the battery. I suspect you will find there is a voltage drop there, check post to post and you should see 0 volts. if there is any voltage indicated it means the breaker is faulty.
[/quote]

Just so there's no misunderstanding, a larger voltage drop at either location comparing the system at "rest" to when the furnace is on is normal.


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## CamperAndy

BoaterDan said:


> Just so there's no misunderstanding, a larger voltage drop at either location comparing the system at "rest" to when the furnace is on is normal.


True, I just wanted to know the at rest voltages as it helps determine state of charge, the working voltages are the real test and that was when I am looking for excessive voltage drop.


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## sleecjr

On thing to add. I had this problem and found that the access cover to the fan was loose. It only had 2 screws and one had got loose. When i put it back on all vents had good air flow.


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