Compressor Fridge Options for a Roadtrek 210P

[engnrsrule]

The installation instructions show side and rear diagrams. Either way it needs two openings. Their drawings all rely on some degree of hot air rising convection. My arrangement is option 1 with supplemental exhaust fans on the upper vent. I have wireless temp indicators and the unit is performing well Refrigerator to whatever set point. Freezer has hit -5°F. Wow, we can travel with Ice Cream!

 

[booster]

Those are very typical drawings for most of the compressor frigs. Some also show the cool air going under the unit also as an option.

As I mentioned, all systems and vans behave differently so it may work fine in the real world, but many have found you can't rely on the heat rising property all the time. Outside wind and sun on the skin of the van can make a difference in airflow and driving can even reverse the flow depending on the aero of the vent areas for creating high or low pressure zones.

Having a simple baffle, or even fiberglass insulation stuffing like I use around the duct area, to separate the inlet and outlet zones can nearly completely negate wind and driving issues on non gravity systems like yours with a fan built in. Does the perforated sheet over the compressor and condenser go all the way across for the exit zone also?

One of the things that I tested over 15 years ago on our first install was having a fan in the upper and no baffles and it was not effective all the time and we would not be able to keep the frig cool and/or used way too much power. With the ducted air to the fan, which is on the condenser pushing through it before going over the compressor unducted to the upper vent. With this setup, the small current from and extra fan increases our power use and gives no cooling benefit. With multiple fans you will be generating some power use that you probably wouldn't need, although with the big battery banks these days that matters less than it used to.

IMO, giving the air no possible way to not go in the inlet vent, though the compressor and condenser, and out the outlet vent is the most effective way to not be surprised by odd conditions that we all hit sometimes.

 

[engnrsrule]

I have long considered adding a scoop on the lower vent.

 

[booster]

I have long considered adding a scoop on the lower vent.

Not surprisingly, I have heard of several owners that have tried variations of that idea, usually in the form of lip spoilers with the spoiler on back edge of the lower vent and forward edge on top vent. When driving that gives a low pressure zone on the upper and high pressure zone on the lower. But it only works when driving or the wind is in the right direction, from the front. When the wind is from the rear it gets reversed. Most of this was done on gas frigs and it also caused so burner blow outs while driving.

 

[youngnretired]

You mean forward edge on the lower and back edge on the upper vents.

I've thought of doing something like that, but without a way to actually control airflow, it figured it would be a waste of my ti.e.

 

[booster]

You mean forward edge on the lower and back edge on the upper vents.

I've thought of doing something like that, but without a way to actually control airflow, it figured it would be a waste of my ti.e.

Nope, not what I mean. A spoiler is like a front air dam on a vehicle will cause a low pressure area behind it so it would suck air out of the upper vent. A spoiler also creates a pressure side on side the wind is hitting so it forces are into the lower vent. That is the flow you want, bottom to top. Think of a vehicle, wind resistance in front slows you down and the rear has a vacuum area. Blocking off the flow in the front with and air dam creates less flow under the van and a low pressure area. This reduces turbulent aiflow under the van which costs mileage and the vacuum helps keep you held down at high speeds.

A good example of it all is the old "wing" windows that cars had at the front of the side windows at the front seating area. They hinged out so the air hit the front of them and they cause it suck air out of cab on the rear side of the glass. You see folks holding their cigarettes there to draw the smoke out the vehicle and not gas us kids in the backseat.

As I mentioned, if you don't have a fan it would work backwards sometimes when parked so was not good for the gas frigs. With most compressor frigs now having fans built in, it is better to control the flow with baffling or ducting as it will be more consistent in most cases.

 

[GallenH]

It will be interesting to see how it performs and how accurate to the specs they give (not much only "average" amps.

This appears to be a Hong Kong based, China manufacturing, company where most of the other mobile frigs are Italian, European of U.S. I think.

Have you seen any real world testing on them anywhere?

Yes. That would be. I believe the Bodega states around 55W average consumption but they don't say what the average refers to (could be over a 24hr period or it could mean depending on ambient temp?). It doesn't seem like it could possibly be for a 24hr period but if it were straight draw wouldn't that mean it would be using 55W/hr which at 12v would be 4,6Ahr.......or for 24hrs 110AH?? I must be mistaken because that seems very demanding

I noticed that the Isotherm 85 llsts 368Whr/24. That would be c.30AH/day. And is that what you got originally or after your work on its controller.

This probably seems like a very confused post to you; sorry.......Keep cool; hot in Phx....Glenn

 

[booster]

Yes. That would be. I believe the Bodega states around 55W average consumption but they don't say what the average refers to (could be over a 24hr period or it could mean depending on ambient temp?). It doesn't seem like it could possibly be for a 24hr period but if it were straight draw wouldn't that mean it would be using 55W/hr which at 12v would be 4,6Ahr.......or for 24hrs 110AH?? I must be mistaken because that seems very demanding

I noticed that the Isotherm 85 llsts 368Whr/24. That would be c.30AH/day. And is that what you got originally or after your work on its controller.

This probably seems like a very confused post to you; sorry.......Keep cool; hot in Phx....Glenn

I don't recall exactly what my final low 24 hr test was but IIRC it was a bit under 25ah/24. Of course you don't see that often in the real world unless it is very cool outside. Real world our old frig would do between that 25ah and as much as 70+ah per day depending on temperatures and use patterns. We haven't had this one in the wide temp ranges yet, but I think it will be similar compared to what we have seen. My old thread about the whole startup and need to modify a lot of stuff to get the new frig as good as the old one was has lots of data points and test results in it.