Recycling lost energy

[Gina D.]

On Friday nite, I set out a nice cool (Not cold.. you'll see why later) fresh bottle of water in the space behind my cooktop and back wall. I was boondocking, so my fridge was running on the 'pane. Outside temp was in the mid 40s, and I don't run the heater at nite.

Normally, it's a can of Dr pepper inside the fridge on the top door shelf. When I want a drink during the nite, I pop the door open, have a swig and drop it back.

The water bottle didn't fit there, so thats why I put it where I did.

In the middle of the nite, I reached up and took a big old gulp of HOT water! Hot as I like my coffee! Just the heat from the fridge coils and fins that is directly below the place where I placed it did that. The fiberglass countertop was acting as a beverage warmer. And a good one at that.

Now, the fridge is vented to the outside, as normal, but heat does rise, not go sideways, so I can see how it would rise up and do that. I have always noted that area was warmish, but never paid much attention.

Would there be a safety issue with cutting a closable vent in that spot and allow the passive heat to rise into the cabin near my bed at nite?

I know you would never recycle furnace or water heater exhaust (And besides impending death from it, why would you want to if the furnace itself is heating the cabin) but I am unaware of any toxic issues with residual heat from fridges.

It wouldn't be a TON of heat, but it seems better than tossing it outside the rig when you don't have a heater on at nite. In early spring and fall, it may just be enough to keep the chill off, especially since I sleep right there.

It would be easy to do, get a small floor vent for a forced air furnace and simply cut a hole and fit it. Close it in the summer or in warm conditions that you wouldn't want heat from there, and redirect it outside. One could even put a small fan behind it to force the heat into the cabin if electrical was not an issue.

Thoughts? Warning? Nobel prize nomination?

[Chester Taje]

Its probably ok if fridge is just on electical. I would not do it on propane. Thats just me.

[Gina D.]

if I am on electric, I use my space heater all nite. How much exhaust from propane is there?.. I obviously know nothing about fridges

[Byron Kinnaman]

I think that what you're getting is heat directly from the open flame. If you were to open up the counter to allow the exhaust from the fridge into the trailer I think youd' be filling the trailer with CO.

Just my humble opinion.

[Frederick L. Simson]

Absorption Fridge Venting article with diagrams

I think you may solve one problem, and create another...

Your Burro 17's Fridge is in an under-the-counter installation, below the 3-burner Cooktop. I wonder if you have a diagonal deflector within the upper vent chamber as shown in the "Almost Good Venting" diagram, or if you have "Bad Venting 2".

What's going to happen to your venting when you install this register?



When I installed my 12 volt computer fans in my upper vent chamber, I noticed that the exhaust air had a faint but definite odor.
Not something I want Inside.

On edit: I also had to install sheet aluminum to replace the dry-rotted wood panel deflector in my vent chamber.

[Per Walthinsen]

I'm with Byron. However, you may not be with us much longer if you open a passage from the burning flame directly into the interior. My thought: don't do it!

From a vague knowledge of your trailer I'll offer the following: The heat on the counter is great for drying dishtowels, but not for helping the frig do its job. If yours is like mine, the perversity of the frig installer must have been considerable. Dometic is quite clear about what it takes: 1) The "outside" of the frig must be sealed from the "inside" of the trailer. I found that the hot air was left to pool over the frig, not go outside like it should. You need a curved sheet metal baffle to direct the rising air outside, and the area over the frig (where the cooktop is) must be sealed up from the back in order to keep your liquids cool. On mine it was a lengthy job to seal things up. Worked though. I've also added a couple of computer fans to pull the air out the upper vent, but have not had the need to use them yet.

A side effect to the complete lack of sealing up was that any water splashed from passing trucks went into the frig compartment and made its way to the interior, under the carpet. I installed a floor drain after sealing it up.

Well, you asked.

[Lisa H.]

Wouldn't putting many bottles of water on the counter to heat up store the heat in the trailer much like a building with a lot of thermal mass stores the heat (or cold) in a passive solar system? I know it would not move the heat toward your sleeping area, but you would be able to use it longer to warm your trailer and would have plenty of hot water in the morning for your coffee and oatmeal.

[Frederick L. Simson]

I'm with Byron. However, [b]you may not be with us much longer if you open a passage from the burning flame directly into the interior. My thought: don't do it!

I got dibs on Gina's trailer after she offs herself. I can put an unsightly patch on the hole in the counter...

[Gina D.]

too late, Uncle Sam has first dibs.

I could build a reflector and possible fit a heat sink on it. In other words, gasses would go out, but heat would be absorbed by the heat sink and passively brought inside the trailer.

It'll be a "thinker" for later.

Thanks for the answers, I had thought it wise to ask first and cut later...

[Pete Dumbleton]

I wouldn't do it. Your water heater, furnace and fridge all burn the same LP in much the same way, so if you wouldn't do it with one, you wouldn't do it with any of them.

LP burns quite cleanly under normal circumstances, or they wouldn't put an LP range in one's home or RV (CO has a cumulative effect), and little if any CO is produced, but why take chances. Unlike the ventfree and catalytic heaters, there is no oxygen depletion sensor or other safety system to shut the fridge down if something were going wrong inside the egg.

I use my vent-free LP heater inside, but don't sleep with it on. Would be hard to control the fridge that way.

[Daniel V.]

I could build a reflector and possible fit a heat sink on it. In other words, gasses would go out, but heat would be absorbed by the heat sink and passively brought inside the trailer.

Some food for thoughts... This Zodi tent heater is designed as a small sealed heat exchanger and does keep the bad gases outside. So, I'm thinking... some sort of coiled air duct passing through the warm space (and sealed in all the right places) could technically do the same thing.

[Roger H]

Gina, I'm with Frederick on this one. Rather than being concerned with recapturing the heat (although that's not a bad idea) I'd be more concerned with improving the efficiency of the fridge.

Merely that a second vent at the top of the fridge is there doesn't mean it's venting effectively. I'd recommend that you install a second deflector that curves from the back (front inside) of the cabinet to the top of the outside vent which will help your fridge vent more efficiently which allows it to work more efficiently. Computer or fridge interior battery fans will do the same thing, but a curved deflector is passive and uses no energy. Trapped heat inside the fridge cabinet indicates that it's probably not a well designed cabinet for the fridge, merely a box into which they stuck it. Most newer trailers actually have a duct that vents through the roof for maximum convection airflow across the coils. It can obviously be made to vent better. An inside curved deflector will also have the secondary benefit of not allowing the countertop to heat up.

Rog

[Ed Harris]

As I posted before with my newer Scamp,The fridge is merely set inside the box formed by the Microwave shelf on top and the base on the bottom.
No attempt at all was made to follow the clear directions specified by Dometic in the manual.
Scamp told me this is how they have always done it and will continue to do it.

On mine there was so much draft created by this giant enclosure that I could feel cold air coming in when I opened the Microwave cabinet door!
The two vents are there but there is no reason the air is drawn in one and out the other.

So last week I cut some plywood and sealed the sides at the very rear of the fridge and sealed the top with an angled piece from the top rear of the fridge to the fiberglass above the top vent.
Then I caulked the seams as best I could(Very Messy) and let it all dry.

It is dramatically warmer inside the trailer now as there is no constant draft through the fridge compartment.
In addition the fridge gas exhaust has to exit the trailer now which must be safer.
Have you noticed that the exhaust is a tiny chimney?
I do not want to inhale from there.

[Gina D.]

Mine is simply under the counter, sealed to the interior of the coach, but there are cheesy lose panels on either side, one creating a cubby side wall, and the other blocking access to under the sink.

The cubby one can be wiggled around and I have even run wires and things thru the gaps when using tools down in that cubby.

I like the heat exchanger idea, and it would be simple to do.

I haven't had too many problems (None at all, with this one) with fridge temps.. but I haven't stayed in 100+ heat often with this one either. That tune may change.

[james kent]

What about cutting a hole and then putting in something like a tin can or a small metal dish? It could be epoxied into place and so keep the seal but would act like an automotive drinkholder but still transfer the heat for you.