Cold air from furnace outlets, extreme cold under curb aft bunk

[Galileo]

Hello all,

Again - sorry if this has been discussed to death previously, but I find the “search” function to be pretty pitiful and have been unable to find anything near what I’m looking for.

On to the question/problem:

We haven’t been out camping much in cold weather until now - ironically - in Florida… go figure.

Anyway - two issues that I’m fairly certain are related:

When the furnace is off - there is often pretty cold (outside) air blowing in from the furnace outlets/registers and no, the heat and fan are off. There are no windows or vents open, so no air going out of the trailer. (So none should be coming IN.) I have a significant “breeze” coming in here…. 

The other issue is that the curb side rear inside side wall below the (closed) window is cold enough to cause significant condensation issues. Upon checking further, under the cushion (and condensation-mitigating mat) there was a LOT of condensation on the access cover over the water valves. 
 

Where is all this cold air entering from?! Something certainly seems to be wide open and allowing cold air infiltration. 

I would HOPE that there isn’t outside air coming into the interior of the trailer from the outside of the furnace - as this is right by the furnace exhaust. (CO anybody?) 

It’s more than a bit of a mystery since there are apparently two pretty big holes in the trailer - one admitting the cold air, and one exhausting inside air to make room for the cold air.

Ironically, the panel over the “basement” and street side of the bed have zero condensation. That’s counterintuitive as the outside access door to basement (on the street side of the trailer) would be an obvious entry point for cold air.

BTW - I don’t even turn the gas furnace on unless it’s deadly cold. We’ve been using a 1,500 watt electric heater while in campgrounds. (Why burn my propane when I can use the electricity I’m paying the campground for?!) Besides, it’s quieter and the heat distribution from the furnace is dismal anyway. (THAT - I found posts for!)

I’ll bet there is a well-known answer to this question. I’m just disappointed that I couldn’t seem to find it….

 

V

[Ray Kimsey]

Sorry I don't have a specific answer to your question, but maybe this will help you search to be more productive.  I like you find the builtin search to be lacking.  I use a Google search and limit it to the forums.  For example you search criteria might be as follows:

site:olivertraveltrailers.com/forums/  cold air entry   

The site limits to whatever you want to limit your search, then just enter your search words.

Hope this helps. 

 

[jd1923]

5 minutes ago, Galileo said:

BTW - I don’t even turn the gas furnace on unless it’s deadly cold. We’ve been using a 1,500 watt electric heater while in campgrounds. (Why burn my propane when I can use the electricity I’m paying the campground for?!) Besides, it’s quieter and the heat distribution from the furnace is dismal anyway. (THAT - I found posts for!)

Not sure where cold air is coming in, but since it is the curbside check that basement area and climb under the trailer in that area. There are 3-4 LP lines that exit the hull to the frame below (Furnace and HWH are easily visible in the rear and further up are lines for gas range and a 4th if you have a LP fridge). Not sure of your hull # but in our older hull all caulk around the LP lines had moved and there was an 1/8" to 1/4" opening around the perimeter of the drilled opening.

I STRONGLY RECOMMEND you store the electric heater for a while and run the furnace. It will heat up that basement area and you will not have the condensation and cold wall between the bed and window. You must have seen my mod post on this. Now that I've done this work, closing the heating duct under the bed and adding an intake filter the furnace works great now and is much quieter.

Electric heaters save money with paid hookups of course but LP is cheaper than the issues you are having and perhaps more. You mentioned Florida, where it is always humid. When we travel somewhere colder, I like to know the furnace is not only keeping us warm but the hulls, the floor, and inside the basement areas to keep the plumbing above freezing. An electric heater will only keep the cabin and upper inner shell warm.

[topgun2]

41 minutes ago, Galileo said:

and one exhausting inside air to make room for the cold air.

Don't forget about those "scupper holes" that are located in the bottom of our trailers.  These are there to allow moisture to be "pulled out" from between the inner and outer shells.

Bill

[John Dorrer]

You need to have windows cracked to allow airflow. You need to be using a dehumidifier. You need to use the trailer furnace to heat under the bed.  

 

This is really operator error. Please don't take this the wrong way. Worst thing to do is keep the trailer closed up. 

 

You need to know when it is time to move to the furnace. The furnace will also help to remove moisture 

When camping with temps below freezing we crack curbside and dinette windows, 1"+. We really have never had a condensation issue.

 

Best of Luck.

[John Dorrer]

1 hour ago, jd1923 said:

Not sure where cold air is coming in, but since it is the curbside check that basement area and climb under the trailer in that area. There are 3-4 LP lines that exit the hull to the frame below (Furnace and HWH are easily visible in the rear and further up are lines for gas range and a 4th if you have a LP fridge). Not sure of your hull # but in our older hull all caulk around the LP lines had moved and there was an 1/8" to 1/4" opening around the perimeter of the drilled opening.

I STRONGLY RECOMMEND you store the electric heater for a while and run the furnace. It will heat up that basement area and you will not have the condensation and cold wall between the bed and window. You must have seen my mod post on this. Now that I've done this work, closing the heating duct under the bed and adding an intake filter the furnace works great now and is much quieter.

Electric heaters save money with paid hookups of course but LP is cheaper than the issues you are having and perhaps more. You mentioned Florida, where it is always humid. When we travel somewhere colder, I like to know the furnace is not only keeping us warm but the hulls, the floor, and inside the basement areas to keep the plumbing above freezing. An electric heater will only keep the cabin and upper inner shell warm.

👍

[Galileo]

5 hours ago, jd1923 said:

You must have seen my mod post on this.

No, as I said, have not been able to find anything applicable via the search function of the forum.

[Galileo]

I thank you all for the suggestions to run the furnace. 
 

That said, running the furnace, using a dehumidifier, or cracking the windows doesn’t address the cause of the problem - cold air entering the trailer in fairly large amounts. If I can feel cold air blowing in through the heat registers - which I can - then there’s a significant opening admitting outside air. The trailer is hardly “closed up” if that is the case. Likewise, if cold air is blowing in, inside air is also leaking out - at a significant amount.

Running the furnace is addressing the symptoms - but ignoring the cause. I suppose if most operators are content to put a band-aid on the problem rather than address the issue - that’s fine - for them. Running the furnace when there’s a large amount of cold air coming in is also pretty inefficient. Like having leaky old double hung windows and no weatherstripping in your home and “solving” the problem by installing a larger furnace.

I do have and use a dehumidifier - I swear by them for my sailboat in NOLA - and they make sense in a lot of cases. Unfortunately, the cold wall in the trailer is a much better “dehumidifier” than mine. As it’s a large, cold surface, it grabs the moisture out of the air better than my dehumidifier. Using a dehumidifier in winter is about the worst time of the year to use it as cold air can hold a lot less moisture. Further reducing the humidity leads to static electricity, nosebleeds, and a generally uncomfortable atmosphere for the people in the trailer - or room in a home. (Probably why virtually every home furnace has a humidifier built in.)

Again - this condensation is in ONE area - JUST above the area where the water valves, water heater, and furnace are. Were it a general humidity problem, there would be a lot more wet areas. Why isn’t the area over the outside access door to the “basement” as bad or worse? It certainly would be more logical for that area to be more prone to outside air infiltration. This tells me that there is a cold air infiltration problem that is localized. As the trailer shell has insulation in this area, it seems clear that it shouldn’t be as open to the outside air as it apparently is.
 

I’ll certainly check the areas where the propane lines go through the hull to the water heater and furnace. I know there are “weep holes” to allow any trapped water between the shell and the liner layers to drain, but they shouldn’t be so large as to cause the significant draft that I’ve described. I’m also suspicious that the cutouts in the shell for the water heater and furnace to have unsealed areas or gaps that are allowing cold air infiltration problem.

Additionally - IF there is one or more openings in the hull near the furnace or the water heater that are admitting and significant amount of outside air - then those holes need to be closed up! Two gas appliances that can generate Carbon Monoxide and air coming into the trailer in that area is a recipe for disaster. Running the furnace in that case is probably the riskiest thing one could do. 

Finally, the furnace ductwork is a whole different set of problems. The register under the bed (king bed floorplan) is the only one that gets decent airflow. The register under the galley cabinets is significantly weaker. The one in the head is a joke - barely enough air coming out to make a candle flicker. Until I can rework the ducts - running the furnace is pretty much ineffective anyway. It only directly heats the area under the bed. I DID see a post or two mentioning how terrible the “return” inlet location for the furnace is. It really wouldn’t be so bad IF the midship and head registers delivered any amount of heated air. 

So - I guess I’m just of the mindset of finding and solving the cause of the problem rather than compensating for air leaks. 

[jd1923]

46 minutes ago, Galileo said:

cold air entering the trailer in fairly large amounts. If I can feel cold air blowing in through the heat registers

Check the furnace in the basement. If cold air is blowing through the ducts, it must be blowing through the heater.

There is a cover panel to see into the heater. Have you inspected the basement area around the furnace?

It is worth running the furnace overnight as previously suggested. You would replace “cold air blowing” with warm air blowing. This is certain.

[Ronbrink]

@Galileo I experienced the exact same issue with cold air intrusion via the heater vents. Since in a CG with electric hookup, I was using my small space heater rather than the gas furnace; this was not in freezing conditions. As a temporary fix, I taped plastic film over all of the vents for the duration of my stay. Prior to covering the vents, I noticed running the wet bath vent exacerbated the issue. We generally don’t camp in cold conditions, so never really tried to chase down this problem. I too would like to know why this was happening. Thanks for raising the question.

Edited January 20 by Ronbrink

[John Dorrer]

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[jd1923]

4 hours ago, Ronbrink said:

I experienced the exact same issue with cold air intrusion via the heater vents. Since in a CG with electric hookup, I was using my small space heater rather than the gas furnace; this was not in freezing conditions...

 I too would like to know why this was happening. Thanks for raising the question.

Two for two now, where the same cause is creating the same issue. The cause is the electric space heater, period.

Your electric heaters are significantly over-heating the upper cabin. Try using an infrared gauge, and measure and compare the temps of your ceiling to that of your floor while running these heaters. You will likely measure a 20-30F difference when its cold enough outside. The electric heater is adding little to no heat in the basement, the lower cabinets, beds and seat cushions, flooring, the ENTIRE lower hull!

Heat can escape the hull above in so many small orifices and the significant heat differential at ceiling creates a turbo effect, forcing this abundance of heat out in any available path. Heat loss through the fan vents, gaps in the A/C seal, the door and windows, the fridge vents, the perimeter around the sewer vent, through the upper cabinets and out everywhere OTT drilled holes for awnings, exterior lights, cameras, etc.

Simple fact, the cold air coming in from below must be equal in volume to hot air escaping above. The furnace vents allow the largest opening to the basement below, path of least resistance is where it is coming into the cabin interior. The cold air from the entire basement (and exterior) is being pulled through the furnace ducts and because these ducts are under the curbside bed, it is your curbside wall and likely under that mattress where condensation is accumulating (colder surfaces).

Those of us running the furnace are creating hot air below in the ducts and pulling cold air in through the intake in exchange. Just run the OEM furnace as designed and the issue that is bothering you will go away!

Being frugal is good, but use your LP (prices coming down soon). Run your OEM furnace when you need to warm your cabin. The electric heater should be used for secondary or back-up heating purposes ONLY.

I haven't use one and will not carry one with us. In the next few months, we will add the Atmos A/C with heat pump. The heat pump will be our backup, but we will still run the furnace as our primary heat. We much prefer an evenly heated cabin, not breathing hot air blowing in our faces.

[Geronimo John]

5 hours ago, jd1923 said:

Your electric heaters are significantly over-heating the upper cabin. Try using an infrared gauge, and measure and compare the temps of your ceiling to that of your floor while running these heaters. You will likely measure a 20-30F difference when its cold enough outside. The electric heater is adding little to no heat in the basement, the lower cabinets, beds and seat cushions, flooring, the ENTIRE lower hull!

I have often thought for very cold weather, that if we could just run our furnace fan on continuously (vs. it cycling with the furnace burner), many of our freezing issues would be ameliorated.  Especially on the curb side.  

The benefit could be expanded to the Aft Port corner (where we generally first see freezing water systems) with the inclusion of an under bed return air duct to that area.  An idea I suggested some time ago.....

GJ 

Edited January 21 by Geronimo John
bolded the direction of the air duct suggested. Return as we don't need the hottest air there, but could likely get by with much cooler air just to prevent freezing in this trouble spot.

[John Dorrer]

1 hour ago, jd1923 said:

Two for two now, where the same cause is creating the same issue. The cause is the electric space heater, period.

Your electric heaters are significantly over-heating the upper cabin. Try using an infrared gauge, and measure and compare the temps of your ceiling to that of your floor while running these heaters. You will likely measure a 20-30F difference when its cold enough outside. The electric heater is adding little to no heat in the basement, the lower cabinets, beds and seat cushions, flooring, the ENTIRE lower hull!

Heat can escape the hull above in so many small orifices and the significant heat differential at ceiling creates a turbo effect, forcing this abundance of heat out in any available path. Heat loss through the fan vents, gaps in the A/C seal, the door and windows, the fridge vents, the perimeter around the sewer vent, through the upper cabinets and out everywhere OTT drilled holes for awnings, exterior lights, cameras, etc.

Simple fact, the cold air coming in from below must be equal in volume to hot air escaping above. The furnace vents allow the largest opening to the basement below, path of least resistance is where it is coming into the cabin interior. The cold air from the entire basement (and exterior) is being pulled through the furnace ducts and because these ducts are under the curbside bed, it is your curbside wall and likely under that mattress where condensation is accumulating (colder surfaces).

Those of us running the furnace are creating hot air below in the ducts and pulling cold air in through the intake in exchange. Just run the OEM furnace as designed and the issue that is bothering you will go away!

Being frugal is good, but use your LP (prices coming down soon). Run your OEM furnace when you need to warm your cabin. The electric heater should be used for secondary or back-up heating purposes ONLY.

I haven't use one and will not carry one with us. In the next few months, we will add the Atmos A/C with heat pump. The heat pump will be our backup, but we will still run the furnace as our primary heat. We much prefer an evenly heated cabin, not breathing hot air blowing in our faces.

Well Stated👏👏

[jd1923]

16 hours ago, Galileo said:

No, as I said, have not been able to find anything applicable via the search function of the forum.

My Mod post linked below -

56 minutes ago, Geronimo John said:

I have often thought for very cold weather, that if we could just run our furnace fan on continuously (vs. it cycling with the furnace burner), many of our freezing issues would be ameliorated.  Especially on the curb side.  

The benefit could be expanded to the Aft Port corner (where we generally first see freezing water systems) with the inclusion of an under bed return air duct to that area.  An idea I suggested some time ago.....

GJ 

By eliminating the furnace duct under the beds, replacing torn ducting, adding an intake filter to slow intake off the floor, creating more pull through the basement, helps considerably in this. 

Then adding vents from cabin to closet, closet to vanity, toilet area to dinette area basement helps to circle cold air below and around the cabin back to the furnace intake. Some have added cabin vents on the streetside, though I went without those to force basement air to and around the lower rear of the Oliver, as GJ mentioned where "freezing water systems" can exist without the furnace running and good basement ventilation.

 

[Chukarhunter]

The maxxair vent and bathroom vent don't seal real tight so a fair amount of warm cabin air can leave through those vents when closed IF and ONLY IF there is a window open or as you appear to have discovered, a source of outside air entering your basement.  I have never experienced condensation under the hatch cover above the furnace like you are so it seems plausible the cold outside air is coming into the basement in that area.  Could it be possible that the outside air intake tube for the furnace has cracked or separated from the combustion chamber inside the furnace housing?  That would allow outside air to flow freely into the furnace housing and then into the basement through the fan intake vents when the furnace is not running but the furnace would probably still work.  It doesn't seem at all likely but that could possibly explain it.  Just a WAG.