Air Mattress ?

getpower1,

We noticed adding a memory foam topper on the OEM mattress in our TC's would also interfere with the wardrobe door being able to be opened. Too high or thick! Just another reason not to have the OEM mattress and having to add a foam topper so it's more comfortable and gives more R-value. Knowing this as we'd checked the dimemsional clearance be for buying our first air mattress, we bwent with an 8" thick one and it doesn't even need a foam topper because it's button push inflation infinitely adjustable inflation. Mattress thickness is usually not an issue with a TT, MH, or 5th wheel but sure is on most TC's cabover beds.

Also learned that any added insulation under a TC bed should be under the mattress as you want to prevent any thermal difference sweating before it can get the mattress wet as mold will grow under it. We use Astro-Foil and some have used closed cell foam board but thickness needed for R-value can still be a problem. Never had any sweating using the Astro-Foil since 1988 and many nights sleeping in -10 F or lower outside the TC temps. Always 70-72 F inside our TC or RV 24/7. Neither of us like to sleep in cold air and especially not when having a bunch of heavy or thick blankets on top. Just a thin blanket or a top sheet. We don't and won't sleep in a cold torture chamber in an RV or at home.

tplife wrote:
This is due to the heat-sink effect of thermo-negative hollow air mattresses. They are only for use in heated enclosures, because they exchange heat to be the same temp as outside air, so if you're sleeping on them, they're working 24/7 to suck the warmth out of you. A cellular foam mattress would need to be 5.0 R-value or better to overcome this, while a hollow air mattress (or cot) is measured at a negative 0.75.

But that doesn't mean there is no way no counter that. As long as there is no heat exchange between you body and the mattress you should be alright. Any memory foam topper would do the trick. ***Link Removed*** about how memory foam reflects your body heat back to you. Even though he's talking about back pain, it's still about keeping warm too.

Thorin wrote:

tplife wrote:
This is due to the heat-sink effect of thermo-negative hollow air mattresses. They are only for use in heated enclosures, because they exchange heat to be the same temp as outside air, so if you're sleeping on them, they're working 24/7 to suck the warmth out of you. A cellular foam mattress would need to be 5.0 R-value or better to overcome this, while a hollow air mattress (or cot) is measured at a negative 0.75.

But that doesn't mean there is no way no counter that. As long as there is no heat exchange between you body and the mattress you should be alright. Any memory foam topper would do the trick. ***Link Removed*** about how memory foam reflects your body heat back to you. Even though he's talking about back pain, it's still about keeping warm too.

The only way to counter the effect is to heat the air around the mattress. Foil under and pads over still allow heat transfer. The memory foam will transfer heat down to the air mattress at a faster rate than it retains heat up. The reason is that the pad/sleeper/mattress are reaching temperature equilibration. They will stop when all are the same temp. This is why air mattresses are only intended for use inside a heated enclosure, and why they don't mention the negative 0.75 R-value at time of sale. A trip to the local UFO or commercial foam outlet will show just how many varieties of this "rises like bread" product is available in for firmness levels and covering options.

"This is due to the heat-sink effect of thermo-negative hollow air mattresses. They are only for use in heated enclosures, because they exchange heat to be the same temp as outside air, so if you're sleeping on them, they're working 24/7 to suck the warmth out of you. A cellular foam mattress would need to be 5.0 R-value or better to overcome this, while a hollow air mattress (or cot) is measured at a negative 0.75."

One of the coldest nights I ever spent was sleeping on an air mattress on concrete in an overcrowded youth hostel garage floor in Paris in May of 1973. (And I was in a military down mummy bag!)

Any air cells with greater than 1/4 inch will convect heat away from the body. Keep an insulation layer between you and the mattress and you are good to go.

Ranger Tim wrote:
Any air cells with greater than 1/4 inch will convect heat away from the body. Keep an insulation layer between you and the mattress and you are good to go.

That insulating layer between you and the mattress will barely slow the heat transfer as it is flattened under you. You need a slow-conducting solid under your pad to slow heat transfer the greatest: liquid the fastest, gas the slower, solid the slowest. That's why ice melts slower if you remove the melted water in the cooler, same laws of thermodynamic transfer.

happycamper1942 wrote:
I tried an air mattress a few years ago in my camper and gave it up as in the cooler weather it would never warm up, we had to put lots of layers between us and it to stay warm.

X2