Installing a Residential refrigerator in the Motorhome

[eXodus]

After my 2 Way fridge died on Ammonia poisoning. I didn't wanted to spent 1400$ for a new or even 600$+ for replacing the cooling unit.
I was lucky and shoot an used residential GE fridge which has right about the same size as my Norcold for about $130. Only a couple of inches higher.


What are the obstacles?


1. Searching an inverter which is running the fridge.
- I love Amazon prime, because I had to sent back 4x Inverter which has not been sufficient.
- not the cheap one and not the expensive one both have their problems.
- 1000w with 2000w surge is not too much for a 120w fridge
- inverters have fans and fans drive me crazy


2. Insulation
- my Norcold has had 6,2 Cubic feet of interior
- the GE has about 10 Cubic Feet of interior and is only 5 inches higher
Where did this space come from ? The walls of the residential fridge are very, very thin.
- A residential fridge is designed to work in about 70-75 degree. In the RV we have got up to 100 degree and more.


So in the moment I'm insulating the refrigerator bay. Reducing the heat which is going into the fridge which should drastically reduce the runtime and the energy consumption.
I've read from people which could reduce their residential fridge power draw by 50%.


Original the fridge is standing on 3 inches of Styrofoam (bottom) here I will add just one Inch. At both sides I have got two layers of 3/4 Styrofoam and one layer of 3/4 Rigid XPS installed.
At the back of the fridge I remove the cooling fins and put also a layer 3/4 Alu backed XPS between the rear wall of the fridge and the hot fins.  On the top I've got three layers of Styrofoam and will add another sheet of Rigid insulation.
In the end of the project I will have:
- 2 1/4 inches at both sides
- 3/4 on the back
- 4 inches on the bottom
- 3 inches on the top

[pvoth1111]

We love our house fridge

[Oz]

Additional topics relating to using a "home refrigerator"


Use an RV or House Refrigerator?
http://www.classicwinnebagos.com/forum/index.php/topic,1571.msg1829.html#msg1829
http://www.classicwinnebagos.com/forum/index.php/topic,3014.msg6566.html#msg6566


Converting 110v House Refrigerator to Solar
http://www.classicwinnebagos.com/forum/index.php/topic,6180.msg24661.html#msg24661

[eXodus]

Thanks Oz !
the problems with a residential are not the amps or the power draw while running. Any medium sized battery bank can handle this.

It is getting a inverter which handles the initial surge, and get against the terrible design flaws which are pretty common in residential units - very poor insulated.
They can have the best compressor but when the walls are only one inch thick, there is always heat getting in.

Why do the manufacturer do this ? Because electricity is way to cheap at home. People want more storage in the fridge and a nice looking one.
They don't want a bulky monster in the kitchen.

I did some measurements with the my new fridge (about 1kwh in 38h )and will recheck with the insulation and get pictures online. Just run out of material and not finished yet.
Got one  4x8feet 3/4 styro panels and one 4x8 rigid alu backed in.
Think I need another styro and half of rigid panel to finish the bay job. Interesting how much insulation goes into this very small bay.

I think I take a another full rigid and will add this also to the doors.
My idea behind this whole insulation project is:  invest $40 in insulation and save $200 in batteries and countless hundreds in fuel/maintenance for generator hours.

Since we are on the go every second or third day my ideal solution would be reduce our energy usage down to which my alternator can charge in 3-4 hours drive.  I'm assuming that my 135amp alternator is not charging more then 40-50A an hour or even less. I have to get down to maybe 120Ah = 1440ah = 1,5kwh for 3 days.

[eXodus]

So I did run the fridge with the Insulation in the bay (didn't put the insulation at the doors yet)

The results are over 50 hour to consume one kwh of batteries. This is very good - especially the fridge is rated with 1kwh per day - on the data sheet. 
I've got some moisture buildup in the fridge, so I'm guessing the door seal is not very good anymore.
Probably have to replace the door gasket at some point. First I try to use petroleum jelly and heat

But so far I'm happy with the results, 1/4 more runtime, and clearly two full nights without recharging. My 3 day goal is in reach.

The inverter does just fine in the battery bay, it's not bad to produce some heat down there do warm up the batteries.

[Rickf1985]

Question, What are you doing as far as ventilation for the cooling fins of the fridge? It is a compressor type fridge if I am reading this correctly so the condenser fins will need decent airflow over them to make the fridge work efficiently. The water vaper could be a clooged or blocked drain, most high effeciency fridges have a small fan to circulate the air inside and this is what evens out the cooling inside and also eliminates the moisture. The moisture will go to a tray around the compressor and be evaporated by the compressor heat. I am not real familiar with the one you have though so I may not be correct on all counts here.

[eXodus]

Hey thanks for questions, I try to upload pics, but the album tool is always crashing in my browser i??

The cooling fins are in the same position like the normal cooling fans of the old fridge had been, on the outside wall of the RV right in front of the ventilation opening and over the fins is the roof vent.
So probably better ventilation then at home where the fridge has only a inch at the top to the cabinet.

I didn't put any insulation around the compressor housing. I don't cover electronics
The fridge is standing upright and the drip water is been collected in a drain pan which is mounted on the compressor for evaporation.

This fridge doesn't have a fan in the inside, it has grills instead of glass plates. This makes passives cooling and air rotation possible. They don't make them anymore because people like glass plates.

Future improvement ideas:
- insulate the doors (material are in the garage, need time)
- Replace door seal (10+ years old) not only not perfectly sealing - they are ugly and I don't want to clean it.
- Install an upwards facing fan behind the fridge to cool the fins - maybe solar or just get the power from the compressor when it's running
- try an batteries operated fan in the inside

[Rickf1985]

I was under the impression that this was a new fridge and not an older one. That explains a lot, the newer "energy saving" fridges have more crap running on them than any of the old ones. This is going to test how OLD some of you are. How many of you remember Crosley refrigerators? We had on in a cabin with the compressor on top and when it came on all you heard was a five second hum and when it went off you heard a little muffled shudder as it wound down. You could not hear it running. That fridge may still be working to this day, it was when the cabin was sold in 89.

[eXodus]

Finally got the pics uploaded:

Bay in progress:

two layers of 3/4 styrofoam at the sides and 4 layers at the top against the roof:

[smg id=6867]
[smg id=6863]


Bay finished with another 3/4 inch Rigid insulation.
[smg id=6865]


Then I removed the cooling fins from the fridge and put another 3/4 Alu in between and the top:
[smg id=6864]
[smg id=6866]

Completely I needed about 4 hours to complete the insulation jobs, it's a lot of measuring, and cutting, not hard just time consuming.
Will probably will do the front doors this week, I really like the look of the Alubacked insulation. Looks like a stainless steel appliance

[eXodus]

I've got somehow bad luck with inverters,

today I discovered that my Inverter has the battery + shorted against the metal Case - right were the cable is attached, so no Fuse would help me..
The inverter works fine as long it's not connected to the frame of the Motorhome... once again back to amazon,

But I stay with the model it's working fine.

Just installed a switch (switching both legs) to change the input of the fridge between inverter and shorepower.

[eXodus]

after 6 days with the fridge running, im getting the opionion that the insulation to the outside is working perfect, the fridge is nearly not responding to outside temp changes. sun on the fridge side, not a problem.

it starts running more frequently as soon as the inside temp goes up. I could see this because we had to run the furnace two nights, and as soon it gets warm inside the compressor kicks in. this means that now the most heat is entering through the doors and seals at the front an not through the wall and roof anymore.

so i will put the insulation panels at the door and will see. I have a temporary fix for the door seals: some petroleum jelly all around and the seal now so thight that its hard to open the fridge

[eXodus]

I've monitored a interesting behavior of the fridge since the day temperatures are now in the upper 80s and middle 90s.

It doesn't cycle more, but runs much longer.
I did a little research and it seems like, a lot of cycling is the symptom of a bad fridge insulation and the temperature rises fast in the fridge.  This I don't have fortunately.

Longer run-times mean that the fridge is not getting not rid of the heat. Every refrigerator is a heat-pump it takes heat (energy) from the inside and transfers it outside. This is basic knowledge. Yet the fridge has to vent the heat on the outside, this only happens when the coils at the outside are OVER ambient temperature.
Basically the compressor has to work longer to rise the temperature so far that the outside is hotter then ambient to vent off heat.

The problem in a standing RV - the fridge vent gets terrible hot before the air starts rising on it's own. You need at least a couple of degree difference to start this process.
So 90s outside the vent has about 100 or more - to start the thermodynamics the coils need to be at 110 or so.

The solution: you see it in every newer fridge in every kitchen:

Add a outside FAN

You lower the effective temperature in the vent over 20 degree since you got forced airflow the coils start cooling at ambient temperature. I read about people that are saving up to 40% of the energy.
Just ordered 4x 120mm computer fans at ebay which I will install in the fridge vent cover at the roof. I also order a 86 Degree thermostat which I will mount to my coils.
Should be an easy project. This computer fans draw very little amps - all 4 together less then 1A.  If they run only during mid day where the fridge sucks most of the energy I could save a lot of amps in my batteries.

Keep you posted

[DonD]

Also compressor fridges start losing efficiency at 50*. When our bus interior gets in the 40s for example, the fridge temp rises as the ambient gets lower. Still cold enough to be safe but the first time it happened I contacted a refer guy and he 'splained this to me.
Some folks that live in really cold places put a light bulb by the compressor to keep it a bit warmer to work better.

Love the res. fridge tho'.. 

[eXodus]

yeah DonD, that's exactly what's happening. The compressor has to run long longer to transfer the same amount of heat.
Thus loosing efficiency. 

[eXodus]

I love to execute ideas:


The fans from ebay arrived 4x 120mm fans with 0.16 amps each which move up to 35 cubic feet per minute a piece. So a total of 140 cfm.  $13 delivered home


I didn't want to go with higher rates since of the amps, and I don't want to hear a fan running all the time. I know these fans are sufficient enough to cool a 500w Gaming-Computer the Airflow should be enough to cool the 120w * 3.x (efficiency rating) of the fridge which is designed to operate passive.


[smg id=7098]
Glued the fans together and added a strip of rigid insulation to one side


[smg id=7097]
installed the fans - it's a tight fit so I did only need two screws on each side to prevent them falling down.


[smg id=7094]
I did wired the fans with a 86 degree thermostat $3 which I mounted to the cold side of the coils on the outside.
My idea behind this - if the fridge is getting rid of all the heat until this point - the fans doesn't have to turn. If not then they should.


[smg id=7096]
But it's Florida we have about 80s and it's not even 9 o clock in the morning. So the I could see the fans starting after a couple of minutes after the compressor turned on.


Now I can feel the air gets sucked in on the bottom of the fridge wall vent. Will see how much this improves my battery life.