Fridge Additional Insulation 2021 TAB 320ss? And other ideas for improving fridge efficiency...

NMSunshine

The fridge in our 2021 Tab 320ss is in the passenger side front corner, so exposed to outside temps radiating through the walls from two sides during summer. 

A significant amount of radiant heat comes through the wall in summer when the sun hits it. This will certainly make the fridge work harder and impact battery life (and fridge life over time, even though these compressor fridges run forever typically).

I borrowed a thermal camera attachment for my phone from a friend and took some interior photos. 

Looking into the cavity after removing the fridge. Outside air temp is 85ºF. So not even a hot day by NM standards. Solar radiation is the enemy here either way. 
Inside trailer temp is about 98ºF, that cool spot low down is close to the floor inside the cabinet and the other cool spots above and beside are the ceiling and walls of the cabinet the fridge sits inside.  


Interesting that you can see the trailer frame radiating heat!
 


Just as a quick test I stuffed in a sheet of foil roll radiant insulation cut to the size of the back of the cabinet, about half an inch thick, and left it for one hour to see how much heat transfer would happen. This was just a quick test, in a permanent install the insulation would be tight to the wall, no gaps etc.


The heat at the top is where the insulation wasn't tight against the wall, but even then some significant improvement. 

A couple of questions come to mind...

1) Has anyone else insulated behind and beside their fridge in the TAB 320?

2) As long as I leave enough room for airflow and keep anything flammable a safe distance away from the stove / protect it with something non-flammable, does anyone see any issues with adding insulation? Not looking for anyone to say its safe, just other possible problems...

3) Looking at the back of the fridge, most of the fridge itself is just blank other than the side with the compressor, heat sinks etc. Is there any reason not to put additional foam sheet insulation on these areas as long as I make sure there's plenty of airflow around the areas that need airflow?

I'm considering adding a temp switched low-current (<0.2a) computer fan to the back to help with airflow either way but need to do some more temp testing first. 

Marceline

I think that you've hit on something interesting here. I attached some reflectix to the front of my clamshell fridge so that the fridge doesn't absorb heat through the black front. I hadn't considered that so much heat could be entering from the trailer sidewall. What happens to your readings if you have an awning on the side of the trailer or something else to block the sun from hitting the sidewall?

NMSunshine

As long as the trailer wall is shaded and before the sun gets high enough to hit it, it's MUCH cooler.

NMSunshine

Looking at the back of the fridge, there's an existing cooling fan zip tied onto the heatsinks. 







It hardly seems to move any air, and what air it does move is headed directly into the flush wall of the cabinet next to the sink. I'm sure it does something, but not very well...

NMSunshine

Actually I was wrong, I powered up the fridge out in the open so I could see what's up and it's actually pulling air away from the heatsink across the compressor which is interesting. Since I had it powered up I also put the thermal camera on it. 





It's a little hard to tell but the 113.5 ºF spot is the refrigerant pipe where it exits the compressor, 117.4ºF is where it enters the heatsink, and the heatsink itself was less than 105º in an ambient temperature of around 91ºF which tells me there may not be a lot of optimization I can do

But you would get heat accumulation in the enclosed space under the cabinet so it will be interesting to check that temp once I put things back together. 

Mickerly

We have a Coleman 13x13ft canopy we put over our 320CS like a carport to keep it in the shade. It reduces the heat in the cabin significantly. That helps the air conditioner and the refrigerator. 

Insulating the sides of the refrigerator would make the box more efficient, but I don't think that is the problem. To increase efficiency of the compressor you need to reduce the temperature behind the refrigerator.

The sides of the trailer are not the larger problem. The front/top/back is the issue. The aluminum sheet collects the sun's heat and the aluminum frame radiates it into the trailer. That's why I chose the "carport" option.

SLJ

I try to park the camper so that corner isn't in direct sun. We usually try to put it in the shade anyway. We use portable solar most of the time. Our awning covers the door side pretty well. I also put put an additional storage tub on that side of the front platform and have notice that helps a lot. You can also hang a cargo blanket over that front corner if you think the sun is a problem.

NMSunshine

@SLJ @Mickerly - I agree 100% - the "carport" shade option is a great idea, same with positioning for shade, external solar etc. Any improvements I'm trying to get here in terms of insulation or airflow are mostly to help while in transit, can't position to shade the front etc, and a little bit of general curiosity about how much improvement I could get with some basic changes. Even 5-10% improvement in compressor cycling over 24hrs adds up, even if it doesn't matter as much when I eventually upgrade batteries etc. 

SLJ

I don't worry about it running when towing. My TV supplies 7.5 amps. More than enough to let the 12 volt fridge run constantly (2.5AH) when towing and still have enough to keep the battery charged. The only time I worry is when the T@B has to sit with the front in the direct sun but if that's the case, the roof solar is cranking out power. I'm running two 100AH lithiums though so I haven't run low on power in a couple of years, even with several rain days with no solar.

NMSunshine

@Mickerly Nice! Yeah good point about the TV, I think something is weird with my wiring as TV isn't putting much into the battery, I need to check that more later. 

Battery upgrade is definitely on the cards in the future, I am thinking portable solar panels first, then lithiums similar scale to yours.

With stock solar even in full sun, clear skies ~18+ volts most of the day right now the fridge seems to run at a net loss over 24hrs, and the stock battery is totally dead in <2 days, so part of this is wondering if I could get the stock solar + stock battery to where it would keep the fridge running consistently while the trailer is just sitting, assuming good sun etc. On 90+ degree days with the sun cooking that end of the camper and pushing internal trailer temps to 110+ that's a pretty big expectation I know.

NMSunshine

After a bit of troubleshooting I discovered my tow vehicle 12v connection wasn't making good contact in the trailer plug. Very gently bending the plug pins so they make better contact has taken that back up to 13v/9.5A or so according to the Victron Smartshunt (with solar off etc). I'm debating installing another smartshunt just as a voltage monitor on the tow vehicle line because I can foresee this getting loose again and it'd be nice to see when it happens. Will just roll with it for a while and see how it goes for now.