JBarca wrote:
Hi Chris, some comments inserted below.
I "was" use to be like you, "thinking" the inside fridge compartment fans were totally separate from the outside fans. I have been using a battery operated Camco inside fridge compartment fan for a long time thinking it was a good thing to do, help keep the air inside all stirred up. Right?
well... I never really thought about the whole situation with an absorption fridge. My brain was still thinking like a compressor driven fridge. Freon compressor systems pump cold air into the fridge compartment. Mixing that air up make senses plus the whole fridge is made to circulate air better inside then a RV style fridge that is packed to the gills most of the time.
The absorption fridge removes heat, and what is left is cold. Right?
Then there are those laws of physics that I keep forgetting some times... hot air rises! Now think of this inside the absorption fridge, the coil fins at the top of the inside fridge compartment are removing heat. The top of the fridge compartment area is where the thermistor sensor is located that cycles the cooling unit. We really only want the hot air up at the coils, we do not need cold air up there when the cooling unit is operating, we only want the inside hot air up at the inside fins/colis.
The air in the bottom of the fridge is colder since the hotter air is rising or already up top. This happens naturally for free. When I put my Camco battery operated fan in the fridge that runs constantly, in time it mixes up all the cold air and the hot air in the fridge. It is disturbing the natural, hot air rises natural process. And the thermistor is then negatively affected by the cold air being circulated around. Yes, in "time" and if no one opens the door, the whole fridge in time comes to equilibrium until the door opens again and new warmer food is put in. But how many times did the boiler have to run to accomplish this?
Once I thought through what is happening inside the fridge, the "ah ha!" moment came to me. You really do not want to stir up all the air inside the fridge, all the time. Just like the outside fans up in the roof vent, you only need the outside fans to run when the boiler is heating. This was simple to see on the outside fans as I wanted to save battery power for boondocking and have longer fan life not running when they did not have to. There is no real value running the outside fans when the boiler is off. The same thing applies to the inside fans if you are only using them to help stop frost/ice from building up on the fins inside the fridge compartment. Thus, inside fans and outside fans should run off the same signal if you decide to add inside defrost fans.
Here is the shorter version at ARP, https://www.arprv.com/rv-fix-fridge-circulation-fan.php
Does that help explain a change in thinking?
You have given some great info about internal air flow/fans/etc INSIDE the fridge...thanks. I hadn't given it much thought. It sounds like from what you have mentioned that the inside the fridge fan should be ON only when the BOILER is on (irrespective of when the roof vent fan is on). If you have a fan INSIDE the refrigerator.
To date, I have not been thinking about putting a fan INSIDE the refrigerator. My internal temps seem fine. I have never done a test to see the temp difference between the bottom shelf vs the top shelf (empty, and/or stuffed with items). Would be interesting to see if there is a temp difference. Anyone know??
Think about this thought, while you did camp down to approx 30F and your fridge appeared inside to be working OK, you really never know if it went into and out of, periods of the boiler is too hot or not. Some small damage may have happened and one would never know. Being below freezing temps, even at 28F etc, and the wind blowing against the side of the fridge vents, changes the amount of excess heat off the boiler. This may well have been going on with my fridge also.
Here in Ohio, we camp all year round. Granted not a lot of winter below freezing at night camping, but spring through fall is very common. Cold snaps overnight in the spring and late fall below freezing exist regularly. How many times did the boiler cycle over night? Who knows, but now we realize what can happen when boiler temps go out range and damage starts to creep in.
I haven't thought about cold weather (below 30*F) camping. I know now, based on learning more about how these refrigerators work, that it would be a good idea to place a heat source in the space behind the refrigerator (ie. 100w light bulb, etc). Sounds like that will help.
You have a good thread here bringing all this up.
John
Thanks! I'm enjoying learning from everyone's knowledge/experience.
PS, You have 3 campers, I have 5 of them... Don't we all need a few spares? :B We have our main camper we use all the time shown in my sig, and 4 older, very wet project campers. One of the project campers is fully restored, one is partly restored and the other two are in many pieces drying out waiting to get restored. I also seem to have many friends needing water damage repair, some small damage, others are full restores. I have just completed my 16th water damaged camper repair. I'm either nuts or like doing this extremely time consuming restoring process. Winter is coming and I'm hoping I can get back onto one of my project campers.
Sounds like you enjoy restoring them....good stuff!
I have 3 because I use them for a unique business idea (...one that is much better than simply renting them out :) ). But I also enjoy doing modifications on them for safety, or comfort, or just for fun. I think I'm addicted!
-Chris
